Mechanics and Life Prediction Branch

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Our Mission

Perform fundamental research for the engineering of structures and materials. Promote scientific understanding of structural and material behavior as it relates to durability and reliability. Develop analytical and experimental tools for design characterization, verification and validation. Support all of NASA's missions and interact with external organizations. Branch members are engaged in several technical societies, participating at various levels from individual members, to committee leads, to local and national officers. The society organizations are:

1) American Society for Testing and Materials International (ASTM) [Non-NASA Link]
2) ASM International (ASMI) [Non-NASA Link]
3) American Ceramics Society (ACerS) [Non-NASA Link]
4) The Minerals, Metals, and Materials Society (TMS)
5) Deutsche Gesellschaft fuer Metallkunde (DGM)
6) American Institute of Aeronautics and Astronautics (AIAA) [Non-NASA Link]
7) American Institute of Mechanical Engineers (ASME) [Non-NASA Link]
8) Society of Automotive Engineers (SAE)
9) Indian Institute of Metals (IIM)
10) American Society of Civil Engineers (ASCE)
11) American Solar Energy Society (ASES)
12) Society of Engineering Science (SES)
13) International Organization for Standardization (ISO) [Non-NASA Link]

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Contact Information

Steven M. Arnold, PhD
Chief
Mechanics and Life Prediction Branch
Structures and Materials Division
NASA Glenn Research Center at Lewis Field
21000 Brookpark Rd.  MS 49-7
Cleveland, OH  44135

Phone: 216-433-3334 Fax: 216-433-8300
EMail: Steven.M.Arnold@nasa.gov
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Products

Publications

Arnold, S.M., Saleeb, A.F., Castelli, M,.G., "A Fully Associative Nonisothermal, Nonlinear Kinematic, Unified Viscoplastic Model for Titanium Alloys, NASA/TM 106926

Bonacuse, P. J. and Kalluri, S., "Cyclic Deformation Behavior of Haynes 188 Superalloy Under Axial-Torsional, Thermomechanical Loading," Thermomechanical Fatigue Behavior of Materials: 4th Volume, ASTM STP 1428, M. A. McGaw, S. Kalluri, J. Bressers, and S. D. Peteves, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2003, pp. 65-80

Bonacuse, P. J. and Kalluri, S., "Elevated Temperature Axial and Torsional Fatigue Behavior of Haynes 188," Journal of Engineering Materials and Technology, Vol. 117, No. 2, April 1995, pp. 191-195

Castelli, M.G., and Ellis, J.R., "Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling," Thermomechanical Fatigue Behavior of Materials, ASTM, STP 1186, H. Sehitoglu , Ed., American Society for Testing and Materials, Philadelphia, 1993, pp. 195-211

Draper, S.L., Lerch , B.A., Pereira, J.M., Nathal, Austin, C.M., and Erdman, O. "The Effect of Ballistic Impacts on the High-cycle Fatigue Properties of Ti-48Al-2Nb-2Cr (Atomic Percent),", Metallurgical and Materials Transactions, volume 32A, 2001, pp. 2743-2785.

Gabb, T. P., Bonacuse, P. J., Ghosn, L. J., Sweeney, J. W., Chatterjee, A., and Green, K. A., "Assessments of Low Cycle Fatigue Behavior of Powder Metallurgy Alloy U720," Fatigue and Fracture Mechanics: 31st Volume, ASTM STP 1389, G. R. Halford and J. P. Gallagher, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 110-127

Kalluri, S. and Bonacuse, P. J., "An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy," Journal of ASTM International, Vol. 7, No. 4, 2010, Paper ID JAI 102717

Kalluri, S. and Bonacuse, P. J., "A Data Acquisition and Control Program for Axial-Torsional Fatigue Testing," Applications of Automation Technology to Fatigue and Fracture Testing, ASTM STP 1092, A. A. Braun, N. E. Ashbaugh, and F. M. Smith, Eds., American Society for Testing and Materials, Philadelphia, 1990, pp. 269-287

Kalluri, S., Bhanu Sankara Rao, K., Halford, G. R., and McGaw, M. A., Deformation and Damage Mechanisms in Inconel 718 Superalloy, Superalloys 718, 625, 706 and Various Derivatives, E. A. Loria, Ed., The Minerals, Metals & Materials Society, Warrendale, PA, 1994, pp. 593-606.

Kalluri, S., Calomino, A. M., and Brewer, D. N., Comparison of Elevated Temperature Tensile Properties and Fatigue Behavior of Two Variants of a Woven SiC/SiC Composite, Ceramic Engineering and Science Proceedings, Vol. 26, Issue 2, Proceedings of the 29th International Conference on Advanced Ceramics and Composites – Mechanical Properties and Performance of Engineering Ceramics and Composites, Edgar Lara-Curzio, Ed., Dongming Zhu and Waltrud M. Kriven, General Eds., pp. 303-310, 2005.

Software

Branch personnel are actively involved in developing software design and analysis tools for simulating and assessing the lifecycle performance of critical structural components. Many of these software programs are used either in conjunction with or as postprocessors to finite element analysis (FEA) programs. In this way, a complete design and analysis package is provided to engineers, enabling cost-effective design of more reliable, efficient, and environmentally conscious components. Listed below are some of the available software codes developed and distributed by Branch personnel.

Augustine's Law Number XVII: Software is like entropy. It is difficult to grasp, weighs nothing, and obeys the Second Law of Thermodynamics; i.e., it always increases. (Norman R. Augustine, Executive Vice President, Martin Marietta Corporation)

CARES - (Ceramics Analysis and Reliability Evaluation of Structures) Ceramics Analysis and Reliability Evaluation of Structures (CARES) is a general-purpose series of integrated design software tools that provide an innovative, cost-effective approach to systematically optimize the design of brittle material components using probabilistic analysis techniques. The CARES series of integrated design software incorporates fundamental mechanics theory and associated computational strategies for isotropic brittle materials component design. CARES is used in conjunction with commercially available FEA (including ANSYS® and ABAQUS), and, therefore, can be applied in general-purpose designs involving the use of brittle materials. CARES is used by over 400 academic, government, and industrial organizations to predict the durability and lifetime of brittle materials (including monolithic structural ceramics, glasses, intermetallics, and ceramic matrix composites) for automotive, aerospace, medical, power generation, and nuclear applications. Development of the CARES series of software continues to evolve and further enhance computational design methodologies for brittle structures. The CARES series of computer software consists of the following three distinct programs:
• CARES/Life The CARES/Life software was developed to predict the reliability and life of structures made from advanced ceramics and other brittle materials such as glass, graphite, and intermetallics. The software is a product of the unique strengths in analytical structural modeling of the Life Prediction Branch at the NASA Glenn Research Center. It links with several commercially-available finite element analysis packages, including ANSYS® and ABAQUS® . To learn more about this software, its capabilities and applications, and/or how to obtain a copy, please visit the CARES/Life website. For additional information on this software, please contact: Noel N. Nemeth Phone: (216) 433-3215 e-mail: Noel.N.Nemeth@nasa.gov • CARES/Creep An integrated design program for predicting the lifetime of structural ceramic components subjected to multiaxial creep loads. This methodology takes into account the time varying creep stress distribution (stress relaxation).
• C/CARES Composite CARES (C/CARES) has been developed to address aerospace design issues relating to ceramic matrix composites. The goal is to predict the time-independent reliability of a laminated structural component subjected to multiaxial load conditions.

CAN - (Composite Analyzer) The CAN series of computer programs are available to perform a comprehensive strength of materials based analysis of continuous fiber reinforced composites. The CAN series of computer software consists of the following three distinct programs:
• ICAN ICAN is an award-winning software designed primarily to address all the aspects pertaining to Polymer Matrix Composites (PMC's) design/analysis. Derivatives of ICAN are ICAN/SCS (for honeycomb sandwich composites), ICAN/PART (Particulate Composites) and ICAN/DMP (damping in composites).
• CEMCAN CEMCAN was developed to address modeling/analysis issues pertaining to ceramic matrix composites (CMC's) and can analyze continuous fiber reinforced laminated composites as well as multiphase constituent advanced woven CMC's.
• METCAN METCAN was developed exclusively to capture the intricate behavior of metal matrix composites (MMC's). This is accomplished by utilizing a unique multi-factor-interaction relationship to account for nonlinearities (arising due to temperature, stress, stress rate, and cyclic loading) in constituent properties in a unified manner.

ImMAC - (Integrated Multiscale Micromechanics Analysis Code) Software Suite The integrated multiscale Micromechanics Analysis Code (ImMAC) suite of software tools enables, for the first time, coupled multiscale analysis of advanced (smart and composite) structures (arbitrary or stiffened), that is from the global to the composite ply to the fiber and matrix constituent scales. Local phenomena (e.g., fiber failures, matrix damage/ inelasticity, interfacial debonding) can be modeled based on the local fields throughout the structure, and the effects on the global structural response can be simulated. Smart material/structural analysis is accomplished via inclusion of recently-developed constitutive models for shape memory alloys and expansion of the thermo-elastic formulation to admit fully coupled thermo-piezo-electro-magnetic effects. The ImMAC suite is composed of three primary programs: MAC/GMC, FEAMAC and HyperMAC:
• MAC/GMC Micromechanics Analysis Code with Generalized Method of Cells composite and smart material analysis program, which constitutes the core of the ImMAC suite. This software determines the effective properties and response of composite materials and laminates based on the arrangement and properties of the constituent materials. MAC/GMC is also specifically designed to integrate with higher scale structural analysis methods. + Visit the MAC/GMC website
• FEAMAC The integration of the MAC/GMC core capabilities within the ABAQUS commercial finite element software package. This multi-scale software enables analysis of structures composed of composite materials by calling a MAC/GMC library directly from ABAQUS to represent the composite material at each integration point in the finite element model. + Visit the FEAMAC website
• HyperMAC The integration of the MAC/GMC core capabilities within the HyperSizer stiffened structural analysis and local structural sizing package. As in FEAMAC, MAC/GMC is called by HyperSizer to represent composite materials at the ply level within stiffened structural analyses. HyperMAC also provides a graphical user interface (GUI) for solving stand-alone MAC/GMC problems.

LEWICE - (LEWis ICE accretion) Software The LEWICE (LEWis ICE accretion) software combines flow field and trajectory calculations with elements modeling the physics of ice growth in order to predict the shape of ice that will form under specified operational and environmental conditions. The program is used by literally hundreds of users in the aeronautics community. Recent updates to the software have included modifications to create a more modular system that will facilitate the substitution of new or improved software elements, and logic updates to improve the prediction of ice shapes generated in the Super-cooled Large Droplet (SLD) regime, an area of increasing concern within the icing community.

IceVal DatAssistant The IceVal DatAssistant icing data management software system has been developed to provide an improved mechanism for management of the large volume of data generated and utilized in the course of performing icing research. The system consists of two primary components: (1) an electronically-searchable relational database, used to store experimental and simulation software-generated ice shape coordinates and the associated operational and environmental conditions data, as well as airfoil coordinates for any relevant airfoils; and (2) a Visual Basic-developed software system, whose graphical user interface (GUI) provides an intuitive, user-friendly mechanism for upload, download, processing and/or display of user-selected data. The relational database component consists of a Microsoft Access database file with nine individual database tables. Included in the database are ice tracing coordinates and associated conditions data from all publicly releasable NASA/Glenn Icing Research Tunnel (IRT)-generated experimental ice shapes to date with complete and verifiable conditions. In addition, simulation software ice shape results for many of the corresponding conditions, generated using the latest version of the LEWICE ice shape prediction code, are likewise included. The system's database access software component was developed using Microsoft Visual Basic 6.0 (VB), and consists of 10 individual VB form modules and an additional 3 VB support modules. In addition to providing the basic data processing and display capabilities, the IceVal GUI also enables the user to perform a variety of database maintenance functions, providing, for example, the ability to compact the current database or to create a new, fully-initialized but empty, database file directly from the IceVal interface.

Patents

This section is under construction.

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Staff

Dr. Steven M. Arnold
Chief Mechanics and Life Prediction Branch
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Steven.M.Arnold@nasa.gov

EDUCATION:
PhD from University of Akron, May 1987 ; Sabbatical , Office National d'Etudes et de Recherches Aerospatiales, Chatillon Cedex, (12/90 - 3/91) France.

WORK EXPERIENCE:
Currently Chief of Mechanics and Life Prediction Branch, and has been employed in the Structures Division, since January of 1988.

RESEARCH & PUBLICATIONS:
Along with management responsibilities conducts research involving theoretical and experimental investigations of structural material behavior of advanced aircraft propulsion systems and spacecraft structures and components. Primary emphasis is on the development of advanced high temperature thermo-viscoelastoplastic deformation and damage constitutive models, and associated multiscale design and analysis computational tools required to make these models accessible to the engineering community.
Research activities resulted in 255 technical publications: 79 of which are journal publications, 3 Co-Edited Special Issues dedicated to Functionally Graded Materials ,10 NASA Tech Briefs, 2 patents.

PROFESSIONAL ACTIVITIES:
Chairman and Co-founder of the Material Data Management Consortium, 2002-present
Member of ASM International, ASME, AIAA

AWARDS & RECOGNITION :
• 2009 College of Engineering Distinguished Alumni Award, University of Akron
• 2004 NASA Glenn Abe Silverstein Award Recipient for Outstanding Research Contributions
• 2005 and 1997 NASA Software of Year, 2nd Place Winner
• 2002, 2000, 1995,1993,1992 Awarded Best Branch Paper

Dr. Brett A. Bednarcyk
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Brett.A.Bednarcyk@nasa.gov

EDUCATION:
Ph.D., M.S., University of Virginia in Applied Mechanics (1997, 1994)
M.E., University of Virginia in Materials Science (1997)

WORK EXPERIENCE:
• 2007 – Present, Materials Research Engineer, Mechanics and Life Prediction Branch, Structures and Materials Division, NASA Glenn Research Center
• 1998 – 2007 Senior Scientist, Ohio Aerospace Institute
• 2001 – 2005 Senior Visiting Research Scientist, University of Virginia

RESEARCH & PUBLICATIONS:
• Development and implementation of multiscale models for advanced composite and smart materials, development of composite bonded joint analysis methods, development and application of design and analysis methods for new composite structural concepts for air breathing and launch vehicles
• Primary developer of NASA GRC's Integrated Multiscale Micromechanics Analysis Code (ImMAC) software suite, with more than 80 users in industry, government, and academia.
• Co-Director of NASA Multiscale Analysis Center of Excellence (MACE)

PROFESSIONAL SOCIETIES/SERVICE:
• Senior Member of the American Institute of Aeronautics and Astronautics (AIAA)
• Member of AIAA Structures Technical Committee and Steering Subcommittee
• 2010 AIAA SDM Conference Organizing Committee – Organized 30 Structures Sessions
• Referee for 14 journals
• Graduate Committee for 5 Ph.D. and 2 M.S. students

AWARDS & RECOGNITION :
• NASA GRC Software of the Year Award, Runner-Up for NASA-wide award (2005)
• 8 NASA Tech Brief Awards, 5 NASA Software Release Awards, NASA Space Act Award
• Lead P.I. for more than $2.5 Million in funded research prior to joining NASA

Pete Bonacuse
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Peter.J.Bonacuse@nasa.gov

EDUCATION:
Continuing studies in Statistics, CWRU (2005-Present)
MS Mechanical and Aerospace Engineering, CWRU (1998)
BSME Mechanical Engineering, U. of Pittsburgh, (1983)

WORK EXPERIENCE:
Software Development Consultant, SASC, 1983-1986
NASA GRC and Army Research Laboratory, Mechanics and Life Prediction Branch, since 1986.

RESEARCH & PUBLICATIONS:
• Experimental methods for durability assessment of materials at elevated temperature; quantitative analysis of material microstructures; probabilistic modeling of defect driven failure.
• 57 technical papers and 58 technical presentations; co-editor of 2 peer reviewed conference proceedings (ASTM Special Technical Publications).

Leadership and Elected/Selected Membership on Technical Panels and Committees:
• NESC Independent Technical Assessment (ITA) for the space shuttle flow liner, 2004
• Scientific Committee for the International Conference on Biaxial/Multiaxial Fatigue, 2000 & 2004
• Vice-Chairman, ASTM Task Group E08.05.02 on Multiaxial Fatigue, 2000-2006

AWARDS & RECOGNITION :
• NESC Group Achievement Award, 11/2004
• NASA Team Achievement Awards, 8/1995 & 10/2003
• US Army Team Achievement Award, 10/2002
• Performance Award, 5/1998
• Special Act Awards, 11/1996 & 8/1997
• NASA Life Prediction Branch Best Paper, 1996 & 1997
• Cleveland Federal Executive Board Award, 1995

Dr. Anthony M. Calomino
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Anthony.M.Calomino@nasa.gov

EDUCATION:
PhD from Northwestern in Materials Science (1994)
MS in Engineering Mechanics, Case Western Reserve University (1987)
BS Structural Engineering, U. Colorado (1980)

WORK EXPERIENCE:
Goble & Associates 1980-1983, Deep Foundation Design
NASA GRC 1986-2010; Mechanics & Life Prediction Branch

RESEARCH & PUBLICATIONS:
• Mechanical behavior and failure phenomenon of high temperature structural materials. Failure analysis of brittle materials.
• 25 refereed journal articles, 60 proceedings and reports.

PROFESSIONAL ASSOCIATIONS & SOCIETIES:
• Chair of the Joint Army Navy NASA Air Force on Materials and Structures
• Chair of the USACA Hypersonics Materials and Structures Committee
• NASA Organizing Member for the National Space and Missiles Symposium

AWARDS & RECOGNITION :
• NASA Manned Space Fight Awareness Award for contributions toward 'Design Certification of Space Station Heat Exchangers (1998).
• NASA Silver Snoopy Award for Personal Achievement and Support of Space Operations Missions (2000)
• NASA Space Flight Awareness Award for Columbia Accident Investigation contributions
• Turning Goals Into Reality Award for development of CMC materials technologies for turbine engines.

Dr. Robert Goldberg
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Robert.Goldberg@nasa.gov

EDUCATION:
PhD in Aerospace Engineering from University of Cincinnati (1999)
MS in Applied Mechanics from Rensselaer Polytechnic Institute (1990)

WORK EXPERIENCE:
NASA Glenn Research Center, Mechanics and Life Prediction Branch, 1991-present.

RESEARCH & PUBLICATIONS:
• Composite mechanics of polymer matrix and ceramic matrix composites. Develops inelastic constitutive equations and micromechanics based analysis methods for these materials. Focuses on deformation, strength and impact analysis of textile composites.
• Over 100 technical publications. 21 articles in refereed journals, 30 NASA Technical Memorandum. Guest editor of issue of Journal of Aerospace Engineering related to impact response of aerospace structures.

PROFESSIONAL SOCIETIES:
• Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA)
• Member of American Society of Mechanical Engineers (ASME)
• Associate Member of American Society of Civil Engineers (ASCE)
• Organized symposium on Ballistic Impact Analysis of Aerospace Structures for ASCE Earth and Space 2008 Conference

AWARDS & RECOGNITION :
• 'Silver Snoopy Award' (Astronauts Personal Achievement Award) (2006)

Dr. Jerry Lang
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email:  Jerry.Lang-1@nasa.gov

EDUCATION:
PhD at North Carolina A&T State University in Mechanical Engineering ; Focus on materials and mechanics of melt-infiltrated ceramic matrix composites.

WORK EXPERIENCE:
With NASA Glenn Research Center, Research and Technology Directorate, since 1997.

RESEARCH & PUBLICATIONS:
• Mechanical behavior and analytical modeling of SiC/SiC melt-infiltration ceramic matrix composites; Thermal and mechanical behavior at elevated temperature and pressure of uncooled C/SiC light weight gas generator chambers for aerospace and aviation applications.
• Authored and co-authored over 40 papers consisting of NASA TMs, articles, and conference proceedings in the field of ceramic matrix materials.

PROFESSIONAL SOCIETIES:
• Member of the American Society of Materials International.
• Member on the executive board and treasurer of the National Technical Association, Cleveland Chapter.
• Session chaired Center for Advanced Materials and Smart Structures and Nanoscience and Nanomaterials, ICCE -10.

AWARDS & RECOGNITION :
• Individual Cash Award, 3 Special Act / Service Awards, and 3 Lewis Awareness Awards.

Dr. Bradley A. Lerch
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: bradley.a.lerch@nasa.gov

EDUCATION:
Dr. rer. nat. in metallurgy from University of Stuttgart, Germany, 1983.
M.S. and B.S. in metallurgical engineering from University of Cincinnati, 1981, 1980.

WORK EXPERIENCE:
• 1987 – Present, Materials Research Engineer, Mechanics and Life Prediction Branch, Structures and Materials Division, NASA Glenn Research Center
• 1986-1987 Post Doc, Material Department, Georgia Institute of Technology
• 1976-1981 Materials Applications Engineer, General Electric Aircraft Division

RESEARCH & PUBLICATIONS:
Conducts fundamental research in the area of deformation and damage mechanisms of materials focusing on metals. Research has resulted in a thorough understanding of deformation and damage mechanisms in high temperature materials, which has guided the development of both constitutive and lifing models, as well as alloy development. Branch POC for testing.
Research activities resulted in 120 technical publications: 61 of which are journal publications.

PROFESSIONAL ACTIVITIES:
Co-chair of Mil-Handbook 17 MMC volume
Member of ASM, TMS, DGM, ACS, ASTM. Fellow of ASM, and officer in Cleveland Chapter.

AWARDS & RECOGNITION :
• 2009 Team Award for Space Shuttle Flow Control Valve Failure investigation
• 2008 Group Acheivement Award for Ice Mitigation Approaches for the External Tank
• 2007 Space Flight Awareness Award (Silver Snoopy) STS-120
• 2007 Composite Materials Handbook Distinguished Service Award
• 2007 Recognized by GE for contributions for gamma TiAl development for the GenX Engine
• 2006 One NASA Peer Award – NASA GRC Ballistic Impact Team.
• 2003 TGIR Award Winner for Mission Affordability - GRCop-84 Alloy Development Team



Dr. Subodh Mital

Affiliation: University of Toledo
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email:  Subodh.K.Mital@nasa.gov

EDUCATION:
PhD, Case Western Reserve University, Cleveland, Ohio (1989) in Civil Engineering.. M.A.Sc University of British Columbia, Vancouver, Canada (1985).

WORK EXPERIENCE:
Senior Research Associate, University of Toledo, Ohio since 1991 (Resident at NASA GRC)
Research Associate, ICOMP, NASA Glenn/Case Western Reserve University. 1989-1991.
Structural Engineer, Engineers India Limited, New Delhi, India. 1981-983.

RESEARCH & PUBLICATIONS:
• Composite micromechanics, mechanics of composite materials and structural analysis. Computational models for deformation behavior of composite materials and physics-based life prediction models of advanced high temperature composites. Probabilistic analysis of composites/structures.
• Over 75 research articles published in refereed journals, NASA Technical Memorandums and Publications (TM/TP) and national/international conference proceedings.

PROFESSIONAL SOCIETIES:
• Senior Member of American Society of Mechanical Engineers (ASME)

AWARDS & RECOGNITION :
• NASA Team achievement award 1996, 1998.
• NASA Turning Goals Into Reality (TGIR) award 2000 and 2004.
• Best paper award Structural Mechanics Branch (1994) and Structures and Acoustics Division (1998).
• Enterprise Development Corporation (EDI) Innovation award 1999.
• Numerous NASA Tech Brief Awards (1993-2009) for technology transfer.

Dr. Pappu L.N. Murthy
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email:  Pappu.L.Murthy@nasa.gov

EDUCATION:
PhD at GA Tech School of Aerospace Eng.(1982) ; Two-year NRC post doctoral fellowship at Glenn, focusing on Composite Mechanics.

WORK EXPERIENCE:
With NASA Glenn Research Center, Structures Division since 1982
NASA Civil Servant since 1988
Areas of Specialty: Composite mechanics, Probabilistic Methods, Composite Overwrapped Pressure Vessels, Optimization & Neural nets

RESEARCH & PUBLICATIONS:
• PMC, MMC, and CMC materials mechanics, probabilistic methods for quantification of scatter, Reliability of Composite overwrapped pressure vessels, Progressive fracture analysis, structural applications for nano-fiber enriched matrix composites.
• Over 300 publications including NASA TMs, TPs, Journal articles and Conference Proceedings. Two best paper presentation awards at conferences, Structures Division best paper award for the "Probabilistic Micro-mechanics and Macro-mechanics of Ceramic Matrix Composites (1998).

PROFESSIONAL SOCIETIES:
• Associate Fellow of AIAA

AWARDS & RECOGNITION :
• NASA Medal for Exceptional Engineering Achievement for contributions toward understanding environmental durability of ceramics and ceramic matrix composites. (2007)
• 'Silver Snoopy Award' (Astronauts Personal Achievement Award) (2005)
• R&D 100 Award (2000) for The development of GENOA software
• NASA Software of the year award (1998) for the development of GENOC/PFA code
• EDI Innovation Award for ICAN computer code for Polymeric Matrix Composites
• NASA Abe Silverstein Award (1998) for Developing Computation tools for Composites

Noel N. Nemeth
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email:  Noel.M.Nemeth@nasa.gov

EDUCATION:
MS (1982) and BS (1980) Cleveland State University in Mechanical Engineering.

WORK EXPERIENCE:
With NASA Glenn Research Center, Mechanics and Life Prediction Branch, since 1991. With Aerospace Design and Fabrication (NASA contractor) from 1982-1990

RESEARCH & PUBLICATIONS:
• Uses applied mechanics, probability and statistics to develop mathematical models, numerical algorithms, and subsequent software for the reliability assessment and life prediction of advanced ceramics and ceramic matrix composite structures in harsh environments.
• 72 technical publications, of which 38 are first author, 25 journal or book articles, 2 NASA Technical Publications, 8 NASA Technical Memorandums, 10 trade magazine articles, 6 NASA Tech Briefs

PROFESSIONAL SOCIETIES:
• Member of the American Ceramic Society (ACerS).
• Member of the American Society of Mechanical Engineers (ASME)

AWARDS & RECOGNITION :
• First ever NASA Software of the Year Award for development of the Ceramics Analysis and Reliability of Structures life prediction code (CARES/Life)
• R&D 100 Award for development of CARES/Life
• American Ceramic Society Corporate Technical Achievement Award for development of an environmentally friendly television picture tube
• Federal Laboratory Consortium Award for excellence in technology transfer
• Steven V. Szabo Engineering Excellence Award

Dr. Jonathan Salem
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email:  Jonathan.A.Salem@nasa.gov

EDUCATION:
PhD from U. Washington in Mechanical Engineering (1998) ; MS in Materials Science, U. Washington (1987).

WORK EXPERIENCE:
With NASA GRC Fatigue & Fracture and Mechanics & Life Prediction Branches since 1981.
Forest City Foundries, Quality Control ,1979 &1980

RESEARCH & PUBLICATIONS:
• Mechanical behavior and failure phenomenon of ceramics and glasses for structural applications. Test method development and standardization. Failure analysis of brittle materials.
• 30 refereed journal articles, 97 proceedings and reports, 3 invited book chapters and 5 consensus standards

PROFESSIONAL SOCIETIES:
• Fellow of the American Society for Testing and Materials.
• Chair of ASTM committee on Advanced Ceramics. Chair ISO TC 206 on fracture toughness.
• Organized and Chaired 2009 International Conference on Advanced Ceramics and Composites

AWARDS & RECOGNITION :
• NASA 'Manned Space Fight Awareness' award for contributions toward Nondestructive Analysis of Space Shuttle Main Engine Liquid Oxygen Ceramic Bearings (1994). NASA 'Engineering and Safety Center Team Award' for "Outstanding Performance in Investigating and Identifying the Most Likely Causes for the Space Shuttle Engine Cutoff Sensor System Anomalies, Permitting a Safe and Timely Return to Space Shuttle Flight "(2009).
• 2004 American Ceramic Society 'Richard M. Fulrath Award' for "Development of Methods for Testing and Design of Structural Ceramics. "
• 1994 'Federal Laboratory Consortium Award for Excellence in Technology Transfer ' for "Verification of Design Code for Brittle Materials."

Dr. Roy M. Sullivan
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email:  Roy.M.Sullivan@nasa.gov

EDUCATION:
PhD in Engineering Science and Mechanics from the Pennsylvania State University, 1990.
MS in Civil Engineering from the University of Virginia, 1984.
BS in Civil Engineering from the Pennsylvania State University, 1982

WORK EXPERIENCE:
NASA Glenn Research Center, Mechanics and Life Prediction Branch, since 1998.
NASA Marshall Space Flight Center, Structures and Dynamics Laboratory, 1985-1998

RESEARCH & PUBLICATIONS:
• High temperature physics and mechanics of polymer matrix (ablative) composites and ceramic matrix composites. Develops constitutive models and numerical solution methods for the analysis of these materials in high temperature applications. Micromechanics of foams and cellular materials.
• More than 70 articles in refereed journals, technical reports and conference proceedings. Structures and Materials Division's Distinguished Publication Award for "A model for the oxidation of carbon silicon carbide composite structures." Carbon 43 (2005)

PROFESSIONAL SOCIETIES:
• Society of Engineering Science
• AIAA

AWARDS & RECOGNITION :
• NASA's Exceptional Achievement Medal 2008, for outstanding contributions toward development and validation of physics-based analytical models for complex structural design of aerospace components.
• Space Shuttle Program's Space Flight Awareness Award (Launch Honoree) 2006.
• Silver Snoopy Award (Astronauts' Personal Achievement Award) 2005

Justin Bail (OAI)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Justin.L.Bail@nasa.gov

EDUCATION:
Master's Degree in Civil Engineering from University of Akron, 12/07
Bachelor's Degree in Mechanical Engineering from Geneva College, 5/04

WORK EXPERIENCE:
Ohio Aerospace Institute, July 2008 – Present
Saint-Gobain Flight Structures, December 2005 – July 2008
Zin Technologies, June 2004 – December 2005

RESEARCH & PUBLICATIONS:
• "Transparent Large Strain Thermoplastic Polyurethane Magneto-active Nanocomposites,"
Mitra Yoonessi, John A. Peck, Justin L. Bail, Bradley A. Lerch, Michael A. Meador – January 2011
•  "Effects of Hygrothermal Cycling on the Chemical, Thermal, and Mechanical Properties of 862/W Epoxy Resin," Sandi G. Miller, Gary D. Roberts, Justin L. Bail, Lee W. Kohlman, and Wieslaw K. Binienda – October 2009 
• " Ballistic Impact Tolerance of Filament-Wound Composite Tubes with Rigid and Flexible Matrix Materials," for Proceedings of the American Society for Composites—Twenty-fifth Technical Conference, S. G. Sollenberger, J. L. Bail, L. Kohlman, C. Ruggeri, C. E. Bakis, G. D. Roberts, E. C. Smith 
• "Approaches for Tensile Testing of Braided Composites," Gary D. Roberts, Jonathan A. Salem, Justin L. Bail, Wieslaw K. Binienda, and Lee W. Kohlman - 5th International Conference on Composites Testing and Model Simulation 
• Computational Fluid Dynamics Case Study on a Constrained Vapor Bubble Control Box Fluid Flow and Thermal Analysis. Tecplot, February 2005. http://www.tecplot.com/Community/CaseStudies/ConstrainedVaporBubbleControlBox.aspx

AWARDS & RECOGNITION :
• Recognized for critical testing that was performed for the problematic hydrogen flow control valves on the Space Shuttle Endeavour that was grounded in February 2009. NASA identified damage to a valve on the shuttle during its November 2008 flight and the testing support aided in the readiness review for the STS-127 Mission that was successfully launched in July of 2009.
• Special Achievement Team Award presented for outstanding work in developing lightweight composite fan containment case technology, and having it incorporated on the new GEnx engine and Boeing's 787 Dreamliner.
• Recognized for dedication and contributions to the zero-gravity exercise studies for improving astronaut health and performance for space exploration conducted in the Exercise Countermeasures Laboratory at NASA Glenn Research Center.

Sharon Priscak (SGT), Support Assistant
TIALS - Stinger Ghaffarian Technologies, Inc. (SGT)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Sharon.Priscak@nasa.gov

EDUCATION:
BA in Business Administration- Akron University

WORK EXPERIENCE:
Stinger Ghaffarian Technologies (SGT)-Branch Support Assistant
Ice Queen of Ohio dba Rosati's Frozen Custard- CEO
Shaker family Center- Assistant to the Executive Director
Planned Parenthood of Greater Cleveland- Assistant to the Medical Director, Head of Purchasing and Software Coordinator
Meldisco Corporation-Sales Representative

PROFESSIONAL ACTIVITIES:
Business Professional Women's Club

AWARDS & RECOGNITION :
2010 Certificate of Appreciation

Eric H. Baker (Analex)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Eric.H.Baker@nasa.gov

EDUCATION:
BA, Mathematics (Computer Science), Ohio Wesleyan University, 1992
MS, Engineering Mechanics, Cleveland State University, incomplete

WORK EXPERIENCE:
Research Aerospace Engineer (resident NASA GRC), subcontractor to Qinetiq NA, 2007-present
Founding Partner/Principal, Connecticut Reserve Technologies, Inc, Cleveland, Ohio, 1996-present
Research Associate (resident NASA GRC), Cleveland State University, Cleveland, Ohio, 1995-2001
Graduate Assistant (resident NASA GRC), Cleveland State University, Cleveland, Ohio, 1993-1995
Intern, NASA/OAI Collaborative Aerospace Internship Program, Cleveland, Ohio, 1994, 1995

COMPUTER EXPERIENCE:
Structural Analysis: ABAQUS, ANSYS, COMSOL, COSMOS/M, NASTRAN, MSC/MARC
Programming Languages: Python, FORTRAN, C/C++, Delphi (OOP Pascal), Visual Basic

RESEARCH & PUBLICATIONS:
• Computer software customization and structural analysis of space-flight and aeronautical hardware. Recent projects include RSRM nozzle material characterization, analysis of composite overwrapped pressure vessels (COPV), analysis of composite fan blade containment cases, nuclear grade graphite material characterization and component reliability analysis. Additionally serves as the current primary developer of the commercially available CARES and WeibPar software programs.
• 14 publications including NASA TMs, TPs, Journal articles and Conference Proceedings
• 2010 NASA GRC RXL branch best paper award for "Effect of Time at Temperature on the X-ply Tensile Modulus of Carbon Cloth Phenolic Composites", Sullivan, R. M., Stokes, E. H., Baker, E. H., NASA/TM-2010-216921, October 2010.

AWARDS & RECOGNITION :
• 2010 NASA Group Achievement Award to the ARES I-X Structural Verification Team, Upper Stage Simulator
• 2010 NASA Certificate of Appreciation for Contribution to the Successful ARES I-X development Flight Test
• 2010 NASA Constellation Team Award for Support of Successful ARES I-X Flight
• 2009 NASA Mission Managers Flight Commendation for Support of Successful ARES I-X Flight
• 2004 Software Release Award LEW-17684-1 "Ceramics Analysis and Reliability Evaluation of Structures Life Prediction Code v. 6.0"
• 2004 Software Release Award LEW-17682-1 "Probabilistic Analysis Techniques Applied to Lifetime Reliability Estimation of Ceramics"

Frederic A. Holland, Jr.
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Frederic.A.Holland@nasa.gov

EDUCATION:
MS Mechanical Engineering, Cleveland State University (1999)
BS Mechanical Engineering, Ohio University (1987)

WORK EXPERIENCE:
NASA Glenn Research Center, Mechanics and Life Prediction Branch, 1988-present.

RESEARCH & PUBLICATIONS:
• Statistical behavior of strength of materials and probabilistic-based design methods including Weibull distribution analysis.
• Aerospace materials database design.
• Authored or co-authored 9 technical publications including NASA technical reports, proceedings and peer-reviewed journals.

PROFESSIONAL SOCIETIES:
Treasurer, National Technical Association/Cleveland Chapter, 1998-2005

AWARDS & RECOGNITION :
• Federal Executive Board's 'Wings of Excellence' Public Service Award, 2009.
• NASA GRC High School Program Mentor of the Year, 2008
• Superior Accomplishment Award for successful proposals for funding research on creep behavior in advanced ceramics, 1999 & 2000.
• Space Act Award for team effort leading to a NASA Tech Brief, 1997.
• NASA Certificate of Recognition for Research on Life Prediction Methods for MMC's, 1997.
• Group Achievement Award for Ceramic Research, 1994.

Dr. Sreeramesh Kalluri (OAI)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Sreeramesh.Kalluri-1@nasa.gov

EDUCATION:
PhD (1987) and MS (1984) in Mechanical Engineering from Case Western Reserve University.
B. Tech. (1981) in Mechanical Engineering from Indian Institute of Technology, Madras.

WORK EXPERIENCE:
Principal Scientist and Research Team Manager, Ohio Aerospace Institute (1998 – Present).
Senior Engineer, FDC/NYMA, Inc., (1994-1998).
Engineer and Senior Engineer, Sverdrup Technology, Inc. (1986-1994).

RESEARCH & PUBLICATIONS:
• Characterization of the mechanical behavior of structural materials used in aeronautical gas turbine engines and spacecraft power generation systems with experimental methods and estimating durability of these materials with analytical tools.
• More than 70 articles in refereed journals, technical reports, and conference proceedings.
• Co-edited four ASTM STP's in fatigue (uniaxial, multiaxial, & thermomechanical) and fracture of materials.

PROFESSIONAL SOCIETIES:
• Fellow of ASTM International; Member of ACerS, AIAA, ASME, and Indian Institute of Metals.
• Chairman of ASTM Subcommittee on Cyclic Deformation and Fatigue Crack Formation (1998-Present).
• Co-Chairman of four ASTM Symposia and three ASTM Workshops on Fatigue and Fracture of materials.

AWARDS & RECOGNITION :
NASA Group Achievement Awards (2008 and 1992).
NASA Turning Goals into Reality (TGIR) Awards (2004 and 2000).
NASA Best Paper in the Branch Awards (2008, 1997, 1996, and 1994).
NASA Tech Brief Award (1998).

David L. Krause
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: krause@nasa.gov

EDUCATION:
MS in Civil Engineering, University of Toledo, 1987
BS in Civil Engineering, University of Akron, 1983

WORK EXPERIENCE:
Research Engineer, Mechanics and Life Prediction Branch, 1995-present
Structural Engineer, NASA GRC Facilities Engineering Division, 1983-1995

RESEARCH & PUBLICATIONS:
• Conducts development and research involving experimental investigations of load-bearing materials for advanced aerospace structures, including power, propulsion, and support systems. Primary emphasis is life assessment, mechanical behavior characterization, and material damage mechanisms for high temperature components subjected to simulated mission and accelerated hostile environmental multiaxial loadings.
• Serves as PI for the Structural Benchmark Test Facility to lead experimental test programs that investigate the multiaxial stress effects on strength, fatigue, creep, and crack growth for thermo-mechanical loadings of test articles and specimens composed of metallic, intermetallic, and other material systems.
• Testing and research activities have resulted in over 80 technical publications, including 37 NASA TM's, 6 journal articles, and the remainder conference proceedings and technical reports.

PROFESSIONAL SOCIETIES:
• Member, ASTM Committee E-8 on Fatigue and Fracture; member of AIAA, ASES, and GEO
• Registered Professional Engineer in the State of Ohio
• Member, GRC Area 9 Safety Committee, expert in structures, pressure vessels, and systems design review

AWARDS & RECOGNITION :
NASA Medal for Exceptional Achievement (2002), for experimental research on advanced composite textiles
James F. Lincoln Gold Award, International Professional Awards Program (1987), for analysis of welded structures
Over 45 GRC and industry performance and group awards, based on merit and recognition of accomplishments

Laurie H. Levinson
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Laurie.H.Levinson@nasa.gov

EDUCATION:
MS in Electrical Engineering, with a Biomedical Specialization, University of Maryland, 1987.
BA in Mathematics and French from Oberlin College, 1978.

WORK EXPERIENCE:
• Computer Engineer, NASA Glenn Research Center, Space Experiments, Engineering, and Structures and Materials Divisions, 1987-Present.
• Electronics Engineer, NASA Goddard Space Flight Center, Engineering Division, 1985-1987.
• Member of Technical Staff, Computer Sciences Corporation, Hubble Space Telescope Project, 1982-1985

RESEARCH & PUBLICATIONS:
• Software requirements definition, design and development, including aircraft icing and materials and structures application software; flight software for the automated, tele-operable Isothermal Dendritic Growth Experiment (IDGE), which flew on the STS-62, STS-75, and STS-87 Space Shuttle Missions, and for the automated Coarsening in Solid-Liquid Mixtures (CSLM) space flight experiment, STS-83 and STS-94; and scientific observation scheduling and command generation subsystems software for the Hubble Space Telescope Software System.
• Technical publications include 1 in a refereed journal and 4 in conference proceedings, 3 NASA Technical Memorandums and 2 NASA Tech Briefs.

AWARDS & RECOGNITION :
• NASA Software of the Year Award, Runner-Up, for LEWICE, Version 3.2.2 (2010).
• NASA Turning Goals Into Reality (TGIR) Award, Aircraft Icing Project Team (2001).
• Silver Snoopy Award (Astronauts' Personal Achievement Award) and Ohio House of Representatives Commendation for the design, development, and superior performance of the IDGE software and for personal contributions during the STS-62 mission resulting in the return of 300% of the planned science data (1994).
• 6 Special Act or Service Awards, 9 Individual Cash/Performance Awards, 2 Quality Increase Awards, 1 Exceptional Space Act Award, 2 NASA Honor Awards, and 4 Inventions and Contributions Board Awards.

Ralph J. Pawlik (Univ. of Toledo)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Ralph.J.Pawlik@nasa.gov

EDUCATION:
Associate in Applied Science, Mechanical Engineering, 1980 Cuyahoga Community College, Cleveland, Ohio.

WORK EXPERIENCE:
• NASA Glenn Research Center, Cleveland, Ohio, 1989-Present
• University of Toledo, Ohio Aerospace Institute and Cleveland State University.
• Bendix Heavy Vehicle Systems, Division of Allied Signal Automotive, Elyria, Ohio.

PROFESSIONAL ACTIVITIES:
• Mentor, Lewis Educational and Research Collaborative Internship Program

Dr. James A. Pennline
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: James.A.Pennline@nasa.gov

EDUCATION:
PhD in Applied Mathematics from University of Virginia.
BS in mathematics (physics minor) from Virginia Military Institute

WORK EXPERIENCE:
• NASA Glenn Research Center, Mechanics and Life Prediction Branch since 2007, Computational Sciences Branch/ CSD since 1991, Computer Service Division supervisory positions prior to 1991.
• Assistant Prof. VCU 1975-80, Assistant Prof. Georgia Tech 1974-75

RESEARCH & PUBLICATIONS:
• Analytical and numerical solutions to integral and differential equations with application to multiple disciplines in science and engineering. General mathematical methodology and modeling . Current research and activity is in bioscience and biomechanical modeling of musculoskeletal systems in the Human Research Program. Technical lead of the Digital Astronaut Project.
• Authored and co-authored over 20 papers consisting of NASA TMs, journal articles, and conference proceedings in the field of engineering applied math, computer science, bioscience.

PROFESSIONAL ACTIVITIES:
Member of the Society for Industrial and Applied Math (SIAM), member of Life Sciences Special Activities Group, member of Mathematical Aspects of Materials Science Activities group.
Professional tutor in Math, Physics, Chemistry,

AWARDS & RECOGNITION :
• 5 Space Act Awards, 6 Group Achievement Awards, 4 Individual Cash or Performance Awards, Special Act or Service Award, NASA Honor Award

Dr. Yoshinori Yamada (OAI)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135

EDUCATION:
Ph.D.Aerospace Engineering, Mississippi State University, 2009;
M.S. Aerospace Engineering, Wichita State University, 2004;
B.S.Mechanical Engineering, Osaka Institute of Technology, 1999

WORK EXPERIENCE:
• 2010 - Present, Senior Scientist, Ohio Aerospace Institute
• 2010, Postdoctoral associate, Mississippi State University

RESEARCH & PUBLICATIONS:
• Experimental characterization of fatigue crack growth behavior and numerical life prediction of fatigue crack growth on metallic materials subjected to constant and variable amplitude loads.
Investigation of fracture behavior on nanotube reinforced Environmental Barrier Coating system using multi scale modeling technique and fracture mechanics.
• Authored and co-authored over 27 papers consisting of 12 journal articles, and 15 conference proceedings.

PROFESSIONAL ACTIVITIES:
American Society of Testing Materials (ASTM) E08 Fatigue and Fracture Committee

AWARDS & RECOGNITION :
• Keith J. Miller Young Investigator Award, ASTM international (2010)
• Best student of the year, Mississippi State University (2005)

Chris Burke (ASRC)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Christopher.S.Burke@nasa.gov

EDUCATION:
• Southwestern Michigan College September 1978 – June 1981 Associates degree, Basic aerospace technology
• Lakeland Community College: Additional engineering courses

WORK EXPERIENCE:
• ASRC - 21000 Brookpark Rd., Cleveland, Oh 44135
• QSS GROUP Inc. - 21000 Brook Park Rd., Cleveland, Oh 44135 - QSS GROUP INC. is a contractual research and engineering group working under contract to the NASA, Glenn research Center.
• Dynacs Engineering Company Inc. - Brook Park, OH

Nathan Wilmoth (ASRC)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: Nathan.G.Wilmoth@nasa.gov

EDUCATION:
• BSME, University of Akron

WORK EXPERIENCE:
• 07-'09; Co-op Test Engineer, Advanced Tire Technology, Bridgestone Americas Tire, LLC
Modify test machine/ design fixtures to allow proprietary multi-axial elastomer testing
Perform mechanical testing to compile data for a material characterization matrix within Finite Element Analysis (FEA) Software
Basic use of FEA Software to verify agreement with mechanical testing
• '09; Co-op Test Engineer, Agricultural Tire, Bridgestone Americas Tire, LLC
Assist with Tractor instrumentation and field testing
Design, Construct, and Test adjustable hydraulic vibration damper for use during tractor/ sled field tests

Zima, John (U of Toledo)
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: John.D.Zima@nasa.gov

EDUCATION:
• Completed Computrain and Exeutrain seminars-DOS, Harvard Graphics, Word Perfect, Excel; Baldwin Wallace College Equivalency courses; Cuyahoga Community College, Parma, OH part time studies in mathematics.

WORK EXPERIENCE:
• OHIO AEROSPACE INSTITUTE/UNIVERSITY OF TOLEDO - 6/02-Present
SENIOR RESEARCH ASSOCIATE
Characterize static failure and environmental durability of silicon carbide reinforced and carbon reinforced ceramic matrix composites. The position involves a relatively high degree of complexity that requires considerable independent creative and professional judgment to complete assigned projects, devise design solutions, and resolve operational problems.
 
• GILCREST ELECTRIC AND SUPPLY - 8/93-Present
MATERIALS TESTING TECHNICIAN
Set up of high temperature composite testing laboratory.
Responsible for the operation and maintenance of MTS and Instron equipment for elevated temperature composite, uniaxial and multi-axial tensile, fatigue, and creep testing.
 
• UNION CARBIDE CORP. (UCAR CARBON CO.) - 12/75-8/93
RESEARCH AND DEVELOPMENT TECHNOLOGIST
Performed technological duties in the areas of coatings for corrosion of graphite and carbon/carbon composites.
Developed unique techniques, such as laser fusion, as well as utilizing conventional processes for application of coatings for business interests and government contracts.
Other areas of activity included graphitization kinetics, carbon fiber intercalation, getters, molding fine grain graphite, hot pressed ceramics, improved strength and toughness of TiB2, wetting experiments, oxidation studies and ceramic and metallic coatings.

Jack Telesman
Structures and Materials Division
NASA Glenn Research Center
21000 Brookpark Rd., Cleveland, OH, 44135
Email: ignacy.telesman-1@nasa.gov

EDUCATION:
MS in Metallurgical Engineering, University of Cincinnati (1983)
BS in Metallurgical Engineering, University of Cincinnati (1979)

WORK EXPERIENCE:
• NASA Glenn Research Center, Materials and Structures, 1983-present.
• Northrop Aircraft, Hawthorne, Ca., Metallic R&D, 1979-1981.

RESEARCH & PUBLICATIONS:
• Mechanical behavior of high temperature gas turbine materials; environmental and time dependent material damage; life prediction methods; alloy development; failure analysis.
• Over 75 research articles published in refereed journals, NASA Technical Memorandums and national/international conference proceedings.

PROFESSIONAL SOCIETIES:
The Minerals, Metals and Materials Society (TMS).
American Society of Testing and Materials (ASTM).
Member of the organizing committee for the Superalloys 2012 Conference.

AWARDS & RECOGNITION :
• Silver Snoopy Award (Astronauts Personal Achievement Award) for solving SSME turbine housing cracking problem.
• NASA Exceptional Service Medal (2004).
• Served on the Independent Assessment Team for the Columbia Mishap Investigation.
• Co-developer of two turbine disk alloys.
• Winner of two best Division Papers awards.
• Consultant and Outside Expert Review panelist to aerospace corporations and DOD on various aerospace related issues and failure investigations.


Collaboration

SBIR Program
The Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) Programs (link opens new browser window) provide an opportunity for small, high technology companies and research institutions to participate in government-sponsored research and development. These programs are significant sources of seed funding for the development of innovations for companies with no more than 500 employees.
http://technology.grc.nasa.gov/sbir/index.shtm

LeRCIP
LeRCIP – is a 10 week summer internship program for both undergrads and grad students.  With mutual consent of both the student and NASA mentor this can be extended to 12 weeks.  Stipends depend upon the year that the student is in, e.g., $4K for freshmen and sophomores, $5K for juniors and seniors, $6K for MS and PhD.  Applications are typically due by January 31.  More info and instructions on how to apply can be found at:
http://www.nasa.gov/centers/glenn/education/LERCIP_GRC.html

To apply go to the following link:
http://intern.nasa.gov/

USRP
USRP – is a NASA wide internship program for college juniors and seniors.  This program runs all year long.  Duration in the Fall and Spring is 15 weeks, 10 weeks in the Summer.  Applications for the summer are typically due by January 23rd.  More information and how to apply can be found at:
http://www.nasa.gov/audience/forstudents/postsecondary/programs/Undergraduate_Student_Research_Project.html

To apply go to the following link:
http://intern.nasa.gov/

GSRP
GSRP – Graduate fellowships that provide up to 3 years of support for graduate work (MS or PhD).  GSRP students receive a stipend of $20K per year, a $6K per year travel allowance (to be used to support costs for traveling to a NASA center to perform research), a $1K allowance for health insurance (if the student has health insurance, then the $1K can be added to the travel allowance) and a $3K University allowance (can be used by the student's thesis advisor for travel, could also be given to the student).  There is a new requirement this year that GSRP students must spend 10 weeks per year at the sponsoring NASA center performing research.  This does not have to be a contiguous 10 weeks and can be broken up into smaller time slots. Proposals for the GSRP are typically due on February 1.  More information on this can be found at: http://fellowships.hq.nasa.gov/gsrp/login/guideline.cfm

Post Doctorate Position
The NASA Postdoctoral Program (NPP) offers unique research opportunities to highly talented national and international individuals to engage in ongoing NASA research programs at a NASA Center, NASA Headquarters, or at a NASA-affiliated research institution. These one- to three-year Fellowship appointments are competitive and are designed to advance NASA's missions in space science, earth science, aeronautics, space operations, exploration systems, and astrobiology. See http://nasa.orau.org/postdoc/ for more information.

Summer Faculty Positions
Ten-week fellowships for full-time science and engineering faculty members, who are U.S. citizens, at accredited US universities and colleges are available at NASA Glenn Research Center (GRC), Cleveland, Ohio, during the summer months.  The proposed research project must be aligned with the research and technology needs of GRC, and have the potential to advance NASA mission. See http://newbusiness.grc.nasa.gov/university-affairs/ngffp/ for more information.

NRAs
NRA – are National Aeronautics and Space Administration (NASA) Research Announcements. These announcements fall under a variety of categories and participation is open to all classes of organizations, including educational institutions, industry, nonprofit organizations, NASA centers, and other Government agencies. Due dates for submission vary depending upon the solicitation, please check out the below URL for specifics. Proposals must be submitted electronically via the NASA Proposal data system NSPIRES (http://nspires.nasaprs.com).

SAA
The National Aeronautics and Space Act of 1958 (the Space Act), as amended, provides NASA with the unique authority to enter into a wide range of "other transactions," commonly referred to as Space Act Agreements (SAAs). NASA enters into SAAs with various partners to advance NASA mission and program objectives, including the conduct of international cooperative space activities. http://technology.grc.nasa.gov/partnering-w-GRC.shtm



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Core Discipline - Material Characterization and Experimental Mechanics

Facilities

Biaxial
Purpose
• Apply in-plane biaxial loads to samples
• Test large samples and components

Capabilities
• Loading up to 110 kips on each axis
• 1500 °C temperature capability
• Test in air, vacuum, inert gas environments
• In-situ crack measurement
• Full field optical strain measurement
• Sample designs: cruciform, beams, plates, films

Uniaxial
Purpose
• Characterize advanced materials for lifing models
• Define influence of load, temperature and environment on material behavior
• Improve fatigue resistance of advanced materials through understanding of microstructure/damage interaction
Capabilities
• 23 uniaxial, 20 kip load frames for cyclic loading
• 14 electromechanical rigs for long term stability. 2 uniaxial
High/Low Frequency (20-300 Hz), 20-kip load frames, 2 high
cycle fatigue rigs (up to 1000Hz), 5 kip load frames
• Temperature capability from -200 to 1550°C
• Computer-controlled software for conducting isothermal and thermomechanical load paths

Tension/Torsion
Purpose
• Characterize advanced materials under Axial-Torsional (A/T) loading for lifting and deformation models
• Define influence of biaxial-load and temperature on material behavior
• Test tubular and structural configuration
Capabilities
• Axial-Torsional (A/T) cyclic loading
• 3 A/T load frames: 50 kip axial load, 20 kip in-toque
• Temperature capability to 1100°C
• Computer-controlled software for conducting complicated thermal and load paths
• Strain measurement by either high temperature biaxial extensometers or full-field optical systems

Dynamic Modulus
Purpose
• Determine Young's and shear modulus over a wide temperature range
• Provide upper bound, rate independent moduli
Capabilities
• Vibrational resonant frequency method
• Measurement of moduli up to 1200°C
• Performed in argon atmosphere
• Enables calculation of Poisson's ratio
• Applicable to most materials

Micro Tester
Purpose
• Test small samples: for example foils, coatings, films, electronic components, MEMS, nanomaterials, fibers, whiskers, wires, bio-materials, brittle or weak materials, foams, and aerogels.
• Apply micro-loads and displacements
Capabilities
• Uniaxial loading
• Static and cyclic load application
• Load capability .0002 lbs to 50 lbs.
• Measures load, strain, displacement, full-field strains.

Conditioning Chambers
Purpose
• Produce controlled moisture states (ranging from dry to water saturated) for characterizing composite properties
• Study the effects of both static and cyclic hygro-thermal conditioning
Capabilities
• Moisture conditioning specimens or panels
• Two temperature/humidity chambers
• One temperature/pressure/humidity chamber
• Air and vacuum ovens

Material Information Management
This section is under construction

Products

Standards
Standards for Advanced Ceramics
ASTM C1368-97
"Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing," Test Method C1368-97, American Society for Testing and Materials Annual Book of Standards, Vol. 15.01, pp. 688-696, ASTM, West Conshohocken, PA, 1998.

ASTM C1421
"Standard Test Method for Fracture Toughness of Advanced Ceramics," Test Method C1421, American Society for Testing Materials Annual Book of Standards, Vol. 15.01, ASTM, West Conshohocken, PA, 2000.

ASTM C1499
"Standard Test Method for Monotonic Equibiaxial Flexural Strength of Advanced Ceramics at Ambient Temperature," Test Method C1499, American Society for Testing and Materials Annual Book of Standards, Vol. 15.01, ASTM, West Conshohocken, Pennsylvania, 2004.

Standards for Composites
ASTM D3410-95
"Standard Test Method for Compressive Properties of Polymer Matrix Composite Materials with Unsupported Gage Section by Shear Loading," ASTM Annual Book of Standards, vol. 15.03, pp. 128-144, ASTM, West Conshohocken, PA, 2002.

ASTM D3479-96
"Standard Test Method for Tension-Tension Fatigue of Polymer Matrix Composite Materials," ASTM Annual Book of Standards, vol. 15.03, pp. 145-150, ASTM, West Conshohocken, PA, 2002.

ASTM D3552-96
"Standard Test Method for Tensile Properties of Fiber Reinforced Metal Matrix Composites," ASTM Annual Book of Standards, vol. 15.03, pp. 176-184, ASTM, West Conshohocken, PA, 2002.

Standards for Fatigue
ASTM E 2207-02
"Standard Practice for Strain-Controlled Axial-Torsional Fatigue Testing with Thin-Walled Tubular Specimens," ASTM Annual Book of Standards, vol. 3.01, pp 1222-1229, ASTM, West Conshohocken, PA, 2003.

ASTM E 2368-04
"Standard Practice for Strain-Controlled Thermomechanical Fatigue Testing," ASTM Annual Book of Standards, vol. 3.01, ASTM, West Conshohocken, PA, 2004.

ASTM E606-92
"Standard Practice for Strain-Controlled Fatigue Testing," ASTM Annual Book of Standards, vol. 3.01, pp 580-594, ASTM, West Conshohocken, PA, 2003.

"Composite Testing and Analytical Methods," Section 1.4, Metal Matrix Composites, Volume 4, CMH-17, ASTM International, West Conshohocken, PA, 2002.
NASA-HDBK-6007 "Handbook of Recommended Material Removal Processes for Advanced Ceramic Test Specimens and Components," (2007)
1)ISO 24370 "Test Method for Fracture Toughness of Monolithic Ceramics at Room Temperature by Chevron-Notched Beam (CNB) Method," ISO 24370:2005, International Organization for Standardization.

Publications
Arnold, S.M., Saleeb, A.F., Castelli, M,.G., "A Fully Associative Nonisothermal, Nonlinear Kinematic, Unified Viscoplastic Model for Titanium Alloys, NASA/TM 106926

Bonacuse, P. J. and Kalluri, S., "Cyclic Deformation Behavior of Haynes 188 Superalloy Under Axial-Torsional, Thermomechanical Loading," Thermomechanical Fatigue Behavior of Materials: 4th Volume, ASTM STP 1428, M. A. McGaw, S. Kalluri, J. Bressers, and S. D. Peteves, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2003, pp. 65-80

Bonacuse, P. J. and Kalluri, S., "Elevated Temperature Axial and Torsional Fatigue Behavior of Haynes 188," Journal of Engineering Materials and Technology, Vol. 117, No. 2, April 1995, pp. 191-195

Castelli, M.G., and Ellis, J.R., "Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling," Thermomechanical Fatigue Behavior of Materials, ASTM, STP 1186, H. Sehitoglu , Ed., American Society for Testing and Materials, Philadelphia, 1993, pp. 195-211

Draper, S.L., Lerch , B.A., Pereira, J.M., Nathal, Austin, C.M., and Erdman, O. "The Effect of Ballistic Impacts on the High-cycle Fatigue Properties of Ti-48Al-2Nb-2Cr (Atomic Percent),", Metallurgical and Materials Transactions, volume 32A, 2001, pp. 2743-2785.

Gabb, T. P., Bonacuse, P. J., Ghosn, L. J., Sweeney, J. W., Chatterjee, A., and Green, K. A., "Assessments of Low Cycle Fatigue Behavior of Powder Metallurgy Alloy U720," Fatigue and Fracture Mechanics: 31st Volume, ASTM STP 1389, G. R. Halford and J. P. Gallagher, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 110-127

Kalluri, S. and Bonacuse, P. J., "An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy," Journal of ASTM International, Vol. 7, No. 4, 2010, Paper ID JAI 102717, Available online at www.astm.org

Kalluri, S. and Bonacuse, P. J., "A Data Acquisition and Control Program for Axial-Torsional Fatigue Testing," Applications of Automation Technology to Fatigue and Fracture Testing, ASTM STP 1092, A. A. Braun, N. E. Ashbaugh, and F. M. Smith, Eds., American Society for Testing and Materials, Philadelphia, 1990, pp. 269-287

Kalluri, S., Bhanu Sankara Rao, K., Halford, G. R., and McGaw, M. A., Deformation and Damage Mechanisms in Inconel 718 Superalloy, Superalloys 718, 625, 706 and Various Derivatives, E. A. Loria, Ed., The Minerals, Metals & Materials Society, Warrendale, PA, 1994, pp. 593-606.

Kalluri, S., Calomino, A. M., and Brewer, D. N., Comparison of Elevated Temperature Tensile Properties and Fatigue Behavior of Two Variants of a Woven SiC/SiC Composite, Ceramic Engineering and Science Proceedings, Vol. 26, Issue 2, Proceedings of the 29th International Conference on Advanced Ceramics and Composites – Mechanical Properties and Performance of Engineering Ceramics and Composites, Edgar Lara-Curzio, Ed., Dongming Zhu and Waltrud M. Kriven, General Eds., pp. 303-310, 2005.

Kalluri, S. and Bonacuse, P. J., "An Axial-Torsional, Thermomechanical Fatigue Testing Technique, Multiaxial Fatigue and Deformation Testing Techniques, ASTM STP 1280" , S. Kalluri and P. J. Bonacuse, Eds., American Society for Testing and Materials, 1997, pp. 184-207

Krause, D.L., Kalluri, S. Shah, A.R. and Korovaichuk,I., "Experimental Creep Life Assessment for the Advanced Stirling Convertor Heater Head," Proceedings of the 8th International Energy Conversion Engineering Conference (IECEC), AIAA Conference Proceedings 2010-7093, Reston, VA (2010).

Krause, D.L. , Kalluri, S., Bowman, R. R., and Shah, A.R. "Structural Benchmark Creep Testing for the Advanced Stirling Convertor Heater Head," Proceedings of the 6th International Energy Conversion Engineering Conference (IECEC), AIAA Conference Proceedings 2008-5774, Reston, VA (2008), pp. 732-741.

Krause, D. L., Kalluri, S., and Bowman, R. R., "Structural Benchmark Testing for Stirling Convertor Heater Heads, Space Technology and Applications International Forum (STAIF-2007):" American Institute of Physics Conference Proceedings, Volume 880, No. 297-1, ed. M. S. El-Genk (Melville, NY: American Institute of Physics, 2007), pp. 297 - 304 (Also see NASA/TM-2007-214934, August 2007, Prepared for STAIF – 2007, Sponsored by the Institute for Space and Nuclear Power Studies at the University of New Mexico, Albuquerque, New Mexico, February 11-15, 2007).

Krause, D.L. and Kantzos, P.T., "Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head," Space Technology and Applications International Forum (STAIF-2006): American Institute of Physics Conference Proceedings, ed. M. S. El-Genk (Melville, NY: American Institute of Physics, 2006).

Krause, D.L., Wittenberger, J.D., Kantzos, P.T. and Hebsur,M.G., "Mechanical Testing of IN718 Lattice Block Structures," Processing and Properties of Lightweight Cellular Metals and Structures, Third Global Symposium on Materials Processing and Manufacturing, ed.s A. K. Ghosh, T. H. Sanders, and T.D. Claar (Warrendale, PA: The Minerals, Metals & Materials Society, 2002), pp 233-242.

Lei, J-.F,, Castelli, M.G. Androjna, D., Blue, C., Blue, R., and Lin, R.Y., "Comparison Testings Between Two High-Temperature Strain Measurement Systems," Vol 36, No. 4, December 1996.

Lerch, B.A., Sullivan, R. M., "Experimental Investigations of Space Shuttle BX-265 Foam," NASA/TM 2009-215292.

Lerch, B.A., Thesken, J.C. and Bunnell,C.T., " Polymethylmethacrylate (PMMA) Material Test Results for the Capillary Flow Experiments (CFE)," NASA/TM 2007-214835.

Lissenden, C.J., Walker, M.A. and Lerch, B.A., "Axial-Torsional Load Effects of Haynes 188 at 650 °C, , Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387", S. Kalluri and P.J, Bonacuse, Eds. American Society for Testing and Materials, West Conshohocken, PA, 200, pp.99-125.

Salem, J.A., Ghosn, L.J., "Back-Face Strain for Monitoring Stable Crack Extension in Precracked Flexure Specimens" Journal of American Ceramic Society, 2010

Salem, J. A., Quinn,G.D., Jenkins, M.G., "Measuring the Real Fracture Toughness of Ceramics: ASTM C1421," pp. 531-553 in Fracture Mechanics of Ceramics: Active Materials, Nanoscale Materials, Composites, Glass, and Fundamentals, R.C. Bradt, D. Munz, M. Sakai and K. White, eds., Springer, (2005).

Salem, J.A. and Weaver, A.S., "Estimation and Simulation of Slow Crack Growth Parameters from Constant Stress Rate Data," pp. 579-596 in Fracture Mechanics of Ceramics: Active
Materials, Nanoscale Materials, Composites, Glass, and Fundamentals, Bradt, R.C., Munz, D., Sakai M. and White, K., eds., Springer, (2005).

Salem, J.A., Powers, L.M., "Guidelines for the Testing of Plates" pp. 357-364 in Proceedings of the 27th International Cocoa Beach Conference on Advanced Ceramics and Composites: B, Ceramic Engineering and Science Proceedings, Vol. 24, No. 4, Waltraud M. Kriven and H.T. Lin, editors (January, 2003).

Books
McGaw, M. A., Kalluri, S., Bressers, J., and Peteves, S. D., Editors, Thermomechanical Fatigue Behavior of Materials: 4th Volume, ASTM STP 1428, ASTM International, West Conshohocken, PA, 2003, Online, Available: www.astm.org/STP/.

Kalluri, S. and Bonacuse, P. J., Editors, Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, American Society for Testing and Materials, 2000.

Kalluri, S. and Bonacuse, P. J., Editors, Multiaxial Fatigue and Deformation Testing Techniques, ASTM STP 1280, American Society for Testing and Materials, 1997.

Consulting
Highly experienced experts stand ready to assist/consult with both internal (NASA) and external customers. Please contact the discipline lead for more information.
Dr. Brad Lerch (bradley.a.lerch@nasa.gov)

Data
Test data are the key result from this discipline. They represent the expenditure of large resources from the Program offices. The resulting data are published in numerous NASA reports and external publications. They are also archived in the Division's Granta MI database. Unrestricted data sets can be requested by contacting the Branch POC. + MDMC - Material Data Management Consortium [Non-NASA link]

Test Method Development
The Branch is involved with state-of-the-art materials and structures. These often present a set of unknown problems associated with the property determination of these materials. A large effort is routinely spent on modifying existing or determining new test methods to characterize or validate models. Resulting concepts are frequently introduced into standards or published in testing journals.

ASTM Special Technical Publication (STP) 1280
Kalluri, S. and Bonacuse, P. J., Editors, Multiaxial Fatigue and Deformation Testing Techniques, ASTM STP 1280, American Society for Testing and Materials, 1997.

ASTM Special Technical Publication (STP) 1387
Kalluri, S. and Bonacuse, P. J., Editors, Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, American Society for Testing and Materials, 2000.

ASTM Special Technical Publication (STP) 1409
Salem, J. A., Quinn, G. D., and Jenkins, M. G., Editors, Fracture Resistance Testing of Monolithic and Composite Brittle Materials, ASTM STP 1409, ASTM International, West Conshohocken, PA, 2002.

ASTM Special Technical Publication (STP) 1428
McGaw, M. A., Kalluri, S., Bressers, J., and Peteves, S. D., Editors, Thermomechanical Fatigue Behavior of Materials: 4th Volume, ASTM STP 1428, ASTM International, West Conshohocken, PA, 2002, (Online, Available: www.astm.org ).

Test Standards Involvement
The Branch plays an active role in the development of testing standards for a wide range of materials. Many standards have been authored/co-authored for Agency, national, and international standards. Standard involvement also includes the development of test methods and participation in interlaboratory, round robin test exercises. Standards developments are important as they tend to: 1) Minimizes errors in generation of technical data used to design components, 2) educate and instill confidence in the engineering community, 3) put everyone on a common basis, allowing direct comparisons of properties and products, 4) aids commercialization, promotes trade, simplifies contracting, and 5) marries lessons learned with production level procedures.

Example: Methodology Improved for Estimating Life-Prediction Parameters for the Design of Industrial Components. One of the factors limiting structural ceramics in long-term applications is stress corrosion, or slow crack growth. For example, airborne water can cause degradation and failure of ceramic components subjected to static loads. Thus, the design of structural components from advanced ceramics requires the measurement of the life-prediction parameters for the particular ceramic material and environment of interest. Recently, the American Society for Testing and Materials standard C1368-97 allowed life-prediction parameters to be measured with such fast stress rates and correspondingly short experimental failure times that significant errors in the life-prediction parameters occurred. As a result, components could not be accurately designed for a long time-to-failure. Results of a current study have been used to revise the American Society for Testing and Materials standard C1368-01 and thereby provide engineers with better data for designing industrial components with long failure times. See this link for further information.

Further our many Round Robin activities provide clear demonstration of how we work with various organizations to develop accurate testing procedures and perform complementary research to fill literature gaps which often time lead to new or improved Standards. Below is a listing of various round robins that we have participated in:

ASTM Round Robins
• Force-controlled and strain-controlled fatigue testing to develop precision and bias statements for E466 and E606 standard.
• Strain-controlled, thermomechanical fatigue testing to develop precision and bias statements for E2368 standard
• Creep-fatigue testing to develop precision and bias statements for E2714 standard
• Strain-controlled, axial-torsional fatigue testing using thin-walled tubular specimens in support of the development of E2207 standard
• Strain-controlled, thermomechanical deformation testing in support of the development of E2368 standard
• Strain-controlled, isothermal fatigue testing on W/Cu metal matrix composite specimens to evaluate applicability of E606 standard to composite materials
• Strain-controlled, isothermal fatigue testing to generate a database with E606 standard
• Impulse Excitation Method for Young's Modulus and Poisson's Ratio to develop precision and bias statements for C1259 standard
• Flexural Strength of Ceramic Matrix Composites to develop precision and bias statements for C1341 standard
• Trans-Laminar Tensile Strength of Ceramic Matrix Composites to develop precision and bias statement for C1468 standard

NIST Round Robins
• Tensile Creep of Silicon Nitride to establish standard properties. Sponsored and organized by NIST in support of ASTM C1291 precision and bias statements

International Energy Agreement Annex II
• Flexural Strength Testing of Ceramics in support of DOE Heat Engine programs and ASTM C1161.
• Effect of Machining Conditions on the Strength of Silicon Nitride run in support of DOE Heat Engine programs
• Tensile Strength Testing of Ceramics to develop precision and bias statement for ASTM C1273.

VAMAS
• Fracture Toughness of Advanced Ceramics by the Surface Crack Method in support of ASTM C1421
• Fracture Toughness of Silicon Nitride at High Temperature (pre-standardization research in support of VAMAS)
• Fractography of Advanced Ceramics (Research in support of C1322)
• Fracture Toughness of Advanced Ceramics at Room Temperature (pre-standardization research in support of VAMAS C1421)
• Fracture Toughness of Ceramic Matrix Composite (pre-standardization research in support of VAMAS)
• Fracture toughness of Ceramics Using the SEVNB Method (pre-standardization research in support of VAMAS)
• Inert Strength of Ceramics (pre-standardization research in support of VAMAS)

Materials Experience
Branch personnel have extensive experience in testing the following material classes under various loading , temperature and environmental conditions.

• Metallics: Nickel, titanium, aluminum, copper, cobalt, steels, foams, lattice block
• Ceramics: Quartz, alumina, silicon nitride, silicon carbide, spinels, sapphire, zinc selenide, hafnium diboride, zinc diboride, ALON, glasses, fused silica
• Polymers: foams, ablators, films, nano-reinforced, bio-materials
• Composites: continuous discontinuously fiber reinforced metal matrix (MMC), PMCs, CMCs, silicon carbide w/titanium diboride particles, silicon nitride w/silicon carbide whiskers, sandwich panels

This experience includes post test evaluations including fractography and microscopy to understand fundamental mechanism of deformation and damage.

Test Method Development
The Branch is involved with state-of-the-art materials and structures. These often present a set of unknown problems associated with the property determination of these materials. A large effort is routinely spent on modifying existing or determining new test methods to characterize or validate models.

For Example : Titanium Aluminide Scramjet Inlet Flap Subelement Benchmark Tested. A subelement-level ultimate strength test was completed successfully on a large gamma titanium aluminide (TiAl) inlet flap demonstration piece. The test subjected the part to prototypical stress conditions by using unique fixtures that allowed both loading and support points to be located remote to the part itself. The resulting configuration produced shear, moment, and the consequent stress topology proportional to the design point. The test was conducted at room temperature, a harsh condition for the material because of reduced available ductility. Still, the peak experimental load-carrying capability exceeded original predictions. See http://www.grc.nasa.gov/WWW/RT/2004/RS/RS03L-krause3.html for more details.

Model/Test Interaction

Example One : Particulate Titanium Matrix Composites Tested--Show Promise for Space Propulsion Applications. Uniformly distributed particle-strengthened titanium matrix composites (TMCs) can be manufactured at lower cost than many types of continuous-fiber composites. The innovative manufacturing technology combines cold and hot isostatic pressing procedures to produce near-final-shape components. Material stiffness is increased up to 26-percent greater than that of components made with conventional titanium materials at no significant increase in the weight. The improved mechanical performance and low-cost manufacturing capability motivated an independent review to assess the improved properties of ceramic titanium carbide (TiC) particulate-reinforced titanium at elevated temperature. Researchers at the NASA Glenn Research Center creatively designed and executed deformation and durability tests to reveal operating regimes where these materials could lower the cost and weight of space propulsion systems. See http://www.grc.nasa.gov/WWW/RT/2003/5000/5920thesken.html and http://www.grc.nasa.gov/WWW/RT/RT2002/5000/5920thesken2.html for more details.

Example Two: Third-Generation TiAl Alloy Tested--Exhibits Promising Properties for Rotating Components. Because of the high compressor inlet and exit temperatures, the Turbine-Based Combined Cycle engine requires higher temperature materials than conventional Ti alloys, and because of its stringent thrust-to-weight requirements, the engine requires low-density material to be utilized wherever possible, e.g., gamma titanium aluminide. Third-generation gamma alloys offer higher temperature capability along with low density and high stiffness. A high-temperature, high-strength γ-TiAl alloy with a high Nb-content (Gamma MET PX1) was selected for evaluation. The microstructure and mechanical properties of Gamma Met PX (GMPX) in both the as-extruded and a lamellar heat-treated condition and the influence of the microstructure on the tensile, creep, and fatigue properties were investigated. See http://www.grc.nasa.gov/WWW/RT/2003/5000/5120draper1.html for more details.

Measurement Techniques
This section is under construction

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Core Discipline - Analytical and Computational Mechanics

Biomechanics
A common disease affecting bones, osteoporosis, literally meaning porous bones, causes loss of bone mass which makes bones brittle and increases the risk of fractures. Space biomedical researchers have amassed data demonstrating that exposure to the environment of space microgravity causes astronauts to lose up to 1% of bone mass per month due to disuse atrophy, a condition similar to osteoporosis. The loss occurs due to the disruption of the process of bone maintenance in the mature adult, bone remodeling, in the function of supporting body weight. The exact signals that cause bone to adapt to a weightless or an Earth 1g environment are still unknown. Whether biomechanical stimuli that are changed by microgravity directly affect osteoblast and osteoclast function or other physiological factors influence bone loss is under investigation. Changes in bones and muscles due to inactivity on Earth cause results similar to those experienced in microgravity. However, it is believed that the mechanism of the loss differs between astronauts, post menopausal women, aging men, and the immobilized. The MLP Branch is working on the development of models to simulate time loss of bone in microgravity and understand the mechanism of bone remodeling as part of a major musculoskeletal goal of protecting the health of a flight crew and ensuring their ability to complete mission tasks. The model combines biomechanical stimulus with cellular dynamics.

For more information: http://spaceflightsystems.grc.nasa.gov/Advanced/HumanResearch/Digital/
Key Reference: http://gltrs.grc.nasa.gov/reports/2009/TM-2009-215824.pdf

Deformation Constitutive Modeling
Deformation constitutive models provide the link between stresses and strains and are thus critical to any solid mechanics model. When considering material nonlinearity, these constitutive models typically divide the material response into reversible and irreversible regimes, with the both the reversible and the irreversible subdivided into time-independent (elastic or plastic) and time-dependent (viscoelastic or viscoplastic) behaviors. Over the past 15 years, MLP Branch personnel have been developing deformation constitutive models for metals, polymers, and ceramics and applying them in analyses of monolithic and composite materials and structures.

Generalized Viscoelastoplasticity with Potential Structure (GVIPS) Models
The GVIPS class of models relies on a complete-potential-based framework and attempts to capture the underlying physical mechanisms associated with microscopic defects (e.g., dislocations, grain boundaries, and voids in metals) and their complicated interactions. For more information:
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX62L-arnold.html
http://www.grc.nasa.gov/WWW/RT/RT2000/5000/5920arnold4.html
Key Reference:
Arnold, S. M., Saleeb, A. F., and Castelli, M. G. (1995) "A fully associative, nonisothermal, nonlinear kinematic, unified viscoplastic model for titanium alloys" NASA-TM-106926.

Pressure-Dependent Bodner-Partom Viscoplastic Model
The Bodner-Partom viscoplastic constitutive model has been extended to account for the effects of hydrostatic stresses, which are important for modeling the nonlinear behavior of polymers. The result is a model that captures not only rate dependence, but also the differences observed between tension and compression tests on polymers. The model is being applied to simulate the response of the matrix in an array of polymer matrx composites under static and dynamic (impact) loading. For more information:
http://www.grc.nasa.gov/WWW/RT/2003/5000/5920goldberg.html
http://www.grc.nasa.gov/WWW/RT/RT2002/5000/5920goldberg.html
http://www.grc.nasa.gov/WWW/RT/RT2000/5000/5920goldberg.html
Key Reference: Goldberg, R.K., Roberts, G.D., and Gilat, A. (2003) "Implementation of an Associative Flow Rule Including Hydrostatic Stress Effects Into the High Strain Rate Deformation Analysis of Polymer Matrix Composites", NASA-TM-2003-212382

Composite Deformation Constitutive Modeling
Constitutive modeling for composites can be accomplished through macromechanics or micromechanics. Macromechanics treats the composite as an effective, homogeneous material and thus usually must account for material anisotropy in the formulation. Micromechanics considers the composite constituent materials discretely, relying on (typically) isotropic constitutive models for the constituents, and uses a theoretical model to arrive at the effective constitutive behavior of the composite. The MLP Branch has a long history of contributions in nonlinear micromechanics theory, simulation, and tool development.

Damage and Lifing Models
Inclusion Failure Modeling
To determine the potential of a nonmetallic inclusion within a metallic alloy to initiate a propagating fatigue crack, models were developed that predict the section and projection parameters of such inclusions. The inclusions are modeled as randomly oriented ellipsoids (as shown below), with the projected area perpendicular to the principal loading direction serving as a good predictor of the inclusion's potential of initiating a crack. These models can be employed in Monte Carlo simulations to assess the probability of the presence of an inclusion that could lead to an anomalously low life. The alternative is the excessively conservative assumption of life being limited by a large inclusion in a high stress location.
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX60L-bonacuse.html
Bonacuse, P.J. (2008) "Geometric Modeling of Inclusions as Ellipsoids" NASA-TM-2008-215477.

Fiber/Matrix Debonding
Fiber/matrix debonding in composites is typically modeled at the micromechanics level by either explicitly including the interface as a separate material, or by introducing a discontinuity at the interface. The latter approach has been taken in the Constant Compliant Interface (CCI) and the Evolving Compliant Interface (ECI) models, which have been implemented in the MLP Branch micromechanics methods. When debonding initiates at a given interface, a discontinuity in the local displacement field is introduced, the magnitude of which is controlled by an interfacial compliance variable (similar to a traction-separation law). After debonding initiates, the CCI model holds the interfacial stress constant, whereas the ECI model enables the interfacial stress to unload. As shown below, the interface behavior can have a primary effect on the composite nonlinear response.
http://www.grc.nasa.gov/WWW/RT/RT2000/5000/5920arnold1.html
Bednarcyk, B.A. and Arnold, S.M. (2002) "Transverse Tensile and Creep Modeling of Continuously Reinforced Titanium Composites with Local Debonding" International Journal of Solids and Structures, Vol. 39, No. 7, 1987-2017. See NASA-TM-2000-210029.

Oxidation Modeling
Material oxidation is a key environmental effect that can impact advanced materials in extreme environments. This is particularly true for C/SiC composites, which otherwise exhibit excellent high temperature properties. The oxidation of the carbon fibers and pyro-carbon coating is the biggest obstacle to the widespread application of C/SiC composites in many future aerospace applications. In-situ oxidation of the C/SiC composite components limits the useful life of the component by degrading the strength and stiffness.

The MLP Branch has developed numerical tools for predicting the oxidation patterns in C/SiC components while in-service in oxidative environments. The models are based on the mechanics of gas flow through a porous medium via both Darcy and Fickian diffusion, and they solve for the partial pressures of the oxide and the oxidant as a function of time and space. These data are used in conjunction with the Arrhenius equation to determine the local rate of carbon oxidation. The oxidation models are capable of capturing the varying oxidation rates throughout C/SiC components that arise due to nonuniform temperature fields, nonuniform oxygen partial pressures, and nonuniform permeability. Current and future work involves understanding the relation between carbon oxidation patterns and strength and stiffness degradation in C/SiC composites.
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX14L-sullivan2.html
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090020523_2009020537.pdf
Sullivan, R.M. (2005) "A Model for the Oxidation of Carbon Silicon Carbide Composite Structures" Carbon, Vol. 43, pp. 275-285.

Progressive Failure Modeling
Progressive failure modeling simulates damage in a material through a change in elastic properties. In its simplest form, the damage progresses instantaneously at a given material point when a particular failure criterion is satisfied. More involved models allow the damage to progress in some more gradual way and can even be combined with nonlinear deformation constitutive models. MLP personnel have been developing, enhancing, and applying such methods for the last decade.

Subcell Elimination Method
The subcell elimination method utilizes the GMC or HFGMC micromechanics models in conjunction with instantaneous damage progression at the constituent level to simulate progressive failure of composite materials. Although the subvolumes (or "subcells") within the composite repeating unit cell fail instantaneously once the local stress/strain field satisfies a selected failure criterion (e.g., Tsai-Hahn), the composite failure response is progressive as the failure of each subcell decreases the composite stiffness only slightly. As shown below, this enables the prediction of both damage initiation and final failure.
Wilt, T.E., and Arnold, S. M.., (1994) ; ''A Coupled/Uncoupled Deformation and Fatigue Damage Algorithm Utilizing The Finite Element Method", NASA-TM-106526
Wilt, T.E., Arnold, S. M.., and Saleeb, A.F., (1997) ''A Coupled/Uncoupled Computational Scheme For Deformation and Fatigue Damage Analysis of Unidirectional MMC's", Applications of Continuum Damage Mechanics to Fatigue and Fracture, ASTM STP 1351, D.L. McDowell, Ed., American Society for Testing and Materials, pp. 65-82.
Moncada, A.M., Chattopadhyay, A., Bednarcyk, B.A., and Arnold, S.M. (2008) "Micromechanics-Based Progressive Failure Analysis of Composite Laminates Using Different Constituent Failure Theories" Proc. 49th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, April, Schaumburg, IL, AIAA 2008-1826.

Mix Mode Continuum Damage Mechanics (MMCDM) Model
The Mix Mode Continuum Damage Mechanics (MMCDM) model introduces damage evolution equations such that a damaging material can follow a given nonlinear stress-strain response curve rather than modeling material failure as instantaneous. The model introduces damage strains and utilizes six scalar damage variables (three for tension, three for compression), allowing an initially isotropic material to become orthotropic due to the presence of damage. Vastly different behavior in tension, compression, and shear can be accommodated by the model (as shown below). The model also includes local final failure criteria are based on mode-specific strain energy release rates and total dissipated strain energy.
Bednarcyk, B.A., Aboudi, J, and Arnold, S.M. (2010) "Micromechanics Modeling of Composites Subjected to Multiaxial Progressive Damage in the Constituents" AIAA Journal, Vol. 48, No. 7, 1367-1378.

Schapery Theory
Like the MMCDM model, Schapery Theory enables damage evolution rather than abrupt failure. The extent of damage in a material is tracked by using the energy released as a material damages as a state variable (see figure below). The evolution of the state variable is determined by correlating its value with experimental data on the reduction of material elastic properties (such as the shear modulus, G12) as the material damages. Schapery theory can be applied at either the composite ply or constituent level.
Pineda, E.J., Waas, A.M, Bednarcyk, B.A., Collier, C.S., and Yarrington, P.W. (2009) "Progressive Damage and Failure Modeling in Notched Laminated Fiber Reinforced Composites" International Journal of Fracture, Vol. 158, 125-143.

Fatigue Damage Modeling
The NonLinear Cumulative Damage Rule (NLCDR) fatigue damage model, and its transversely isotropic generalization, solves the inverse cyclic fatigue problem. That is, rather than applying a given number of cycles to a material and determining the damage level, this approach calculates the number of cycles required to reach a given level of damage. If the material constitutive response is nonlinear, there is a clear computational advantage to the approach, and, if the problem involves a structure rather than a material point, after a given damage level is reached, the stress can be redistributed in the structure based on the current damage level. Damage increments can thus be repeatedly applied until final failure occurs resulting in a fatigue life prediction that includes the effects of stress redistribution.
Arnold, S. M., Kruch, S., (1991) ''Differential Continuum Damage Mechanics Models for Creep and Fatigue of Unidirectional Metal Matrix Composites", NASA-TM-105213.
Kruch, S. and Arnold, S. M.., (1997) ''Creep Damage and Creep-Fatigue Damage Interaction for Metal Matrix Composites ''Applications of Continuum Damage Mechanics to Fatigue and Fracture, ASTM STP 1351, D.L. McDowell, Ed., American Society for Testing and Materials, pp. 7-28.
Bednarcyk, B.A. and Arnold, S.M. (2002) "Fully Coupled Micro/Macro Deformation, Damage, and Failure Prediction for SiC/Ti-15-3 Laminates" Journal of Aerospace Engineering, Vol. 14, No. 3, 74-83. See also NASA-TM-2001-211343.

Efficient Structural Analysis Methods
Simplified Shear Solution
The simplified shear solution (SSS) provides a means to approximate the distribution of through-thickness shear stresses in a composite laminate due to an applied global through-thickness shear load. Traditional methods for determining this shear stress distribution involve solution of a boundary value problem associated with the geometry of the laminated plate. In contrast, the SSS relies only on the force, moment, and shear resultants at a particular areal location in a laminated plate (along with the ply material properties and lay up information) with no knowledge of the plate dimensions or boundary conditions. It is thus analogous to lamination theory, which provides approximations of the in-plane stress distributions in a laminate, and, like lamination theory, it can be used in conjunction with shell-based structural finite element models to determine the ply level stress states for design and sizing purposes. The SSS has been implemented within the HyperSizer structural sizing software where it can be applied to the design of both composite laminates and composite stiffened panels.
http://www.techbriefs.com/component/content/article/8630
Bednarcyk, B.A., Aboudi, J. and Yarrington, P.W. (2007) "Determination of the Shear Stress Distribution in a Laminate From the Applied Shear Resultant – A Simplified Shear Solution" NASA-CR-2007-215022.

Local Buckling Methods
Local buckling is a critical failure mechanism for modern composite panels, which are often subjected to significant compressive loads. In order to evaluate a candidate panel design for a particular application, efficient methods are needed to predict the onset of local buckling. Such methods have been developed for two novel composite panel concepts; Reinforced Core Sandwich (RCS) (a.k.a. Fiber Reinforced Foam) and PRSEUS (see below). A key feature of RCS panels is the presence of lightweight foam, which stabilizes the internal composite webs and the composite facesheets against local buckling. To capture these effects, methods that localize the panel loads to the webs and facesheets and then consider buckling on an elastic foundation have been developed and implemented. For PRSEUS, local buckling of the stringer, local buckling of the frame web/foam, local buckling of the spacing span region between the stiffeners (including both the bare facesheet and the bonded flange regions), and torsional buckling of the stringer were considered. Facesheet post-buckling was also considered as PRSEUS' inclusion of stitching between the facesheet and stringer flange enhances the bond strength, enabling safe operation into the locally post-buckled regime. These local buckling methods have been implemented into the HyperSizer structural sizing software.
Bednarcyk, B.A., Yarrington, P.W., Lucking, R.C., Collier, C.S., and Ainsworth, J.J. (2011) "Efficient Design and Analysis of Lightweight Reinforced Core Sandwich and PRSEUS Structures" 52nd AIAA/ASME/ASCE/AHS/ACS Structures, Structural Dynamics, Materials Conference, April 4-7, Denver, Co.

Bonded Joint Solutions
Bonded composite joints are becoming more prevalent in aerospace vehicle designs, and thus efficient methods are needed that can assess bonded joint integrity early in the design process. An analytical method for predicting the stress fields and failure of an array of bonded joint types has been developed and implemented within the HyperSizer structural sizing software. The adherends are treated as arbitrary laminate in generalized cylindrical bending joined by the adhesive, which is modeled using a traction-separation law. By enforcing equilibrium in the different regions of the joint, a system of 1st order ODEs is developed, which can be solved by direct integration, subject to continuity and boundary conditions. Ply-level in-plane and interlaminar stresses can be recovered. Compared to other analytical methods for bonded joint analysis, the this method is capable of handling more general situations, including various joint geometries, linear and nonlinear adhesives, asymmetric and unbalanced laminates, and various loading and boundary conditions.
Zhang, J., Bednarcyk, B.A., Collier, C.S., Yarrington, P.W., Bansal, Y., and Pindera, M.-J. (2006) "Analysis Tools for Adhesively Bonded Composite Joints, Part II: Unified Analytical Theory" AIAA Journal, Vol. 44, 1709-1719.

Foam Mechanics
As part of the Space Shuttle Return to Flight effort after the Columbia accident, NASA undertook a significant effort to improve the understanding of the External Tank spray-on foam insulation thermo-mechanical behavior. This rigid, closed-cell, polyurethane foam is characterized by elongated tetrakaidecahedron cells (see below), which cause the foam to exhibit anisotropic behavior. MLP Branch personnel have developed closed-form expressions for the effective mechanical properties and strengths of these foams based on the average foam cell dimensions by treating the cell edges as structural members possessing both axial and flexural rigidity and by applying the minimum potential energy theorem to the unit cell.
Sullivan, R.M., Ghosn, L.J., Lerch, B.A., and Baker, E.H. (2009) "Elongated Tetrakaidecahedron Micromechanics Model for Space Shuttle External Tank Foams" NASA/TP-2009-215137.

Micromechanics
GMC
The generalized method of cells (GMC) is a micromechanics theory that considers a material with periodic microstructure. It has been applied extensively to model composite materials. A rectangular or parallelepiped (in the case of triple periodicity) repeating unit cell (RUC) is identified and discretized into an arbitrary number of subvolumes or "subcells", each of which may contain a distinct material (see below). The rectangular (or parallelepiped) graphical representation of the subcells indicates the region of influence of its centroid, not the actual fiber or matrix shape. The theory assumes a first-order displacement field and enforces continuity of tractions and displacements between adjacent subcells in an average sense, so the influence of subcell corners does not enter into the formulation. The method provides the effective, fully multiaxial, nonlinear constitutive behavior of the heterogeneous RUC, along with concentration equations that give access to the local fields in each subcell. These local fields enable use of arbitrary nonlinear constitutive and damage models for the constituent materials, and the impact of the local nonlinearities on the effective material response is predicted. Further, because the theory provides effective constitutive behavior, it can be implemented within higher scale structural models as a nonlinear, anisotropic constitutive model. The GMC has been demonstrated to provide excellent effective composite behavior predictions in many cases. As shown above, the local fields predicted by GMC, while representative, are somewhat approximate in nature.
Aboudi, J. (1995) "Micromechanical Analysis of Thermo-Inelastic Multiphase Short-Fiber Composites" Composites Engineering, Vol. 5, pp. 839-850. See also NASA-CR-1994-195290.

HFGMC
The High-Fidelity Generalized Method of Cells (HFGMC) micromechanics theory employs a higher-order displacement field compared to GMC. This provides the theory with higher-fidelity local fields (see below), but requires solution of more equations, which adversely affects the method's computational efficiency. Like GMC, HFGMC considers a repeating unit cell composed of subcells and provides both the effective constitutive response of the material along with local fields. Unlike GMC, in the presence of nonlinearity, HFGMC tracks the field variables at a number of integration points within the subcells as a single centroidal value is no longer sufficient to capture the varying fields within a subcell. The efficiency, mesh dependence, and local field fidelity of HFGMC are intermediate with respect to FEA and GMC.
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5920arnold1.html
Aboudi, J., Pindera, M.-J., and Arnold, S.M. (2003) "Higher-Order Theory for Periodic Multiphase Materials with Inelastic Phases" International Journal of Plasticity, Vol. 19, pp. 805-847

HOTFGM
The Higher-Order Theory for Functionally Graded Materials is a theory designed to analyze heterogeneous structures with explicit coupling between the micro and macro scales. As shown at left, the analysis geometry, like GMC and HFGMC considers a rectangular or parallelepiped region composed of an arbitrary number of subcells. However, unlike GMC and HFGMC, which are periodic, HOTFGM considers the boundaries of the analysis domain. The presence of free edges along with the explicit heterogeneous microstructure of the considered material captures the interaction of the microstructural details with the macroscopic boundaries, which cannot be captured if the material is homogenized and only effective behavior is considered at the macro scale. Two-dimensional, three-dimensional, and cylindrical versions of the theory have been developed and implemented in computer programs. The theories have been used extensively to examine functionally graded materials, thermal barrier coatings, actively cooled structures, and free-edge effects.
http://www.grc.nasa.gov/WWW/RT/RT2000/5000/5920arnold3.html
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5920arnold2.html
Aboudi, J., Pindera, M.-J., and Arnold, S.M. (1999) "Higher-Order Theory for Functionally Graded Materials" Composites Part B, Vol. 30, pp. 777–832.

Strength of Materials Approach
The strength of materials approach is one of the earliest and most accessible micromechanics methods developed for analysis of composite materials. It is based on the application of iso-stress and iso-strain assumptions (a.k.a., Voigt and Reuss assumptions) in various directions to arrive at effective properties for a composite repeating unit cell. Additional assumptions have been incorporated within the approach for specific classes of composites in order to improve the correlation with experiment. For example, for polymer matrix composites, the fact that the stiffness of the matrix is typically much lower than that of the fiber can simplify the equations. Such an assumption cannot be used for metal and ceramic matrix composites, rather, a fiber matrix interphase, and the associated more complex repeating unit cell can be considered to improve the approach's predictions. Factors have also been introduced that enable the strength of materials micromechanics equations to better correlate with measured composite strength data and to better represent composite nonlinear response.
Chamis, C.C. (1984) "Simplified Composite Micromechanics Equations for Hygral, Thermal, and Mechanical Properties" SAMPE Quarterly, April.

Multiscale Design/Analysis
This section is under construction

Ablative Mechanics
This section is under construction

Probabilistic Lifing
This section is under construction

Products
Software
Branch personnel are actively involved in developing software design and analysis tools for simulating and assessing the lifecycle performance of critical structural components. Many of these software programs are used either in conjunction with or as postprocessors to finite element analysis (FEA) programs. In this way, a complete design and analysis package is provided to engineers, enabling cost-effective design of more reliable, efficient, and environmentally conscious components. Listed below are some of the available software codes developed and distributed by Branch personnel.

Augustine's Law Number XVII: Software is like entropy. It is difficult to grasp, weighs nothing, and obeys the Second Law of Thermodynamics; i.e., it always increases. (Norman R. Augustine, Executive Vice President, Martin Marietta Corporation)

CARES - (Ceramics Analysis and Reliability Evaluation of Structures) Ceramics Analysis and Reliability Evaluation of Structures (CARES) is a general-purpose series of integrated design software tools that provide an innovative, cost-effective approach to systematically optimize the design of brittle material components using probabilistic analysis techniques. The CARES series of integrated design software incorporates fundamental mechanics theory and associated computational strategies for isotropic brittle materials component design. CARES is used in conjunction with commercially available FEA (including ANSYS® and ABAQUS), and, therefore, can be applied in general-purpose designs involving the use of brittle materials. CARES is used by over 400 academic, government, and industrial organizations to predict the durability and lifetime of brittle materials (including monolithic structural ceramics, glasses, intermetallics, and ceramic matrix composites) for automotive, aerospace, medical, power generation, and nuclear applications. Development of the CARES series of software continues to evolve and further enhance computational design methodologies for brittle structures. The CARES series of computer software consists of the following three distinct programs:
• CARES/Life The CARES/Life software was developed to predict the reliability and life of structures made from advanced ceramics and other brittle materials such as glass, graphite, and intermetallics. The software is a product of the unique strengths in analytical structural modeling of the Life Prediction Branch at the NASA Glenn Research Center. It links with several commercially-available finite element analysis packages, including ANSYS® and ABAQUS® . To learn more about this software, its capabilities and applications, and/or how to obtain a copy, please visit the CARES/Life website. For additional information on this software, please contact: Noel N. Nemeth Phone: (216) 433-3215 e-mail: Noel.N.Nemeth@nasa.gov • CARES/Creep An integrated design program for predicting the lifetime of structural ceramic components subjected to multiaxial creep loads. This methodology takes into account the time varying creep stress distribution (stress relaxation).
• C/CARES Composite CARES (C/CARES) has been developed to address aerospace design issues relating to ceramic matrix composites. The goal is to predict the time-independent reliability of a laminated structural component subjected to multiaxial load conditions.

CAN - (Composite Analyzer) The CAN series of computer programs are available to perform a comprehensive strength of materials based analysis of continuous fiber reinforced composites. The CAN series of computer software consists of the following three distinct programs:
• ICAN ICAN is an award-winning software designed primarily to address all the aspects pertaining to Polymer Matrix Composites (PMC's) design/analysis. Derivatives of ICAN are ICAN/SCS (for honeycomb sandwich composites), ICAN/PART (Particulate Composites) and ICAN/DMP (damping in composites).
• CEMCAN CEMCAN was developed to address modeling/analysis issues pertaining to ceramic matrix composites (CMC's) and can analyze continuous fiber reinforced laminated composites as well as multiphase constituent advanced woven CMC's.
• METCAN METCAN was developed exclusively to capture the intricate behavior of metal matrix composites (MMC's). This is accomplished by utilizing a unique multi-factor-interaction relationship to account for nonlinearities (arising due to temperature, stress, stress rate, and cyclic loading) in constituent properties in a unified manner.

ImMAC - (Integrated Multiscale Micromechanics Analysis Code) Software Suite The integrated multiscale Micromechanics Analysis Code (ImMAC) suite of software tools enables, for the first time, coupled multiscale analysis of advanced (smart and composite) structures (arbitrary or stiffened), that is from the global to the composite ply to the fiber and matrix constituent scales. Local phenomena (e.g., fiber failures, matrix damage/ inelasticity, interfacial debonding) can be modeled based on the local fields throughout the structure, and the effects on the global structural response can be simulated. Smart material/structural analysis is accomplished via inclusion of recently-developed constitutive models for shape memory alloys and expansion of the thermo-elastic formulation to admit fully coupled thermo-piezo-electro-magnetic effects. The ImMAC suite is composed of three primary programs: MAC/GMC, FEAMAC and HyperMAC:
• MAC/GMC Micromechanics Analysis Code with Generalized Method of Cells composite and smart material analysis program, which constitutes the core of the ImMAC suite. This software determines the effective properties and response of composite materials and laminates based on the arrangement and properties of the constituent materials. MAC/GMC is also specifically designed to integrate with higher scale structural analysis methods. + Visit the MAC/GMC website
• FEAMAC The integration of the MAC/GMC core capabilities within the ABAQUS commercial finite element software package. This multi-scale software enables analysis of structures composed of composite materials by calling a MAC/GMC library directly from ABAQUS to represent the composite material at each integration point in the finite element model. + Visit the FEAMAC website
• HyperMAC The integration of the MAC/GMC core capabilities within the HyperSizer stiffened structural analysis and local structural sizing package. As in FEAMAC, MAC/GMC is called by HyperSizer to represent composite materials at the ply level within stiffened structural analyses. HyperMAC also provides a graphical user interface (GUI) for solving stand-alone MAC/GMC problems.

LEWICE - (LEWis ICE accretion) Software The LEWICE (LEWis ICE accretion) software combines flow field and trajectory calculations with elements modeling the physics of ice growth in order to predict the shape of ice that will form under specified operational and environmental conditions. The program is used by literally hundreds of users in the aeronautics community. Recent updates to the software have included modifications to create a more modular system that will facilitate the substitution of new or improved software elements, and logic updates to improve the prediction of ice shapes generated in the Super-cooled Large Droplet (SLD) regime, an area of increasing concern within the icing community.

IceVal DatAssistant The IceVal DatAssistant icing data management software system has been developed to provide an improved mechanism for management of the large volume of data generated and utilized in the course of performing icing research. The system consists of two primary components: (1) an electronically-searchable relational database, used to store experimental and simulation software-generated ice shape coordinates and the associated operational and environmental conditions data, as well as airfoil coordinates for any relevant airfoils; and (2) a Visual Basic-developed software system, whose graphical user interface (GUI) provides an intuitive, user-friendly mechanism for upload, download, processing and/or display of user-selected data. The relational database component consists of a Microsoft Access database file with nine individual database tables. Included in the database are ice tracing coordinates and associated conditions data from all publicly releasable NASA/Glenn Icing Research Tunnel (IRT)-generated experimental ice shapes to date with complete and verifiable conditions. In addition, simulation software ice shape results for many of the corresponding conditions, generated using the latest version of the LEWICE ice shape prediction code, are likewise included. The system's database access software component was developed using Microsoft Visual Basic 6.0 (VB), and consists of 10 individual VB form modules and an additional 3 VB support modules. In addition to providing the basic data processing and display capabilities, the IceVal GUI also enables the user to perform a variety of database maintenance functions, providing, for example, the ability to compact the current database or to create a new, fully-initialized but empty, database file directly from the IceVal interface.

Publications
Arnold, S.M., Saleeb, A.F., Castelli, M,.G., "A Fully Associative Nonisothermal, Nonlinear Kinematic, Unified Viscoplastic Model for Titanium Alloys, NASA/TM 106926

Bonacuse, P. J. and Kalluri, S., "Cyclic Deformation Behavior of Haynes 188 Superalloy Under Axial-Torsional, Thermomechanical Loading," Thermomechanical Fatigue Behavior of Materials: 4th Volume, ASTM STP 1428, M. A. McGaw, S. Kalluri, J. Bressers, and S. D. Peteves, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2003, pp. 65-80

Bonacuse, P. J. and Kalluri, S., "Elevated Temperature Axial and Torsional Fatigue Behavior of Haynes 188," Journal of Engineering Materials and Technology, Vol. 117, No. 2, April 1995, pp. 191-195

Castelli, M.G., and Ellis, J.R., "Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling," Thermomechanical Fatigue Behavior of Materials, ASTM, STP 1186, H. Sehitoglu , Ed., American Society for Testing and Materials, Philadelphia, 1993, pp. 195-211

Draper, S.L., Lerch , B.A., Pereira, J.M., Nathal, Austin, C.M., and Erdman, O. "The Effect of Ballistic Impacts on the High-cycle Fatigue Properties of Ti-48Al-2Nb-2Cr (Atomic Percent),", Metallurgical and Materials Transactions, volume 32A, 2001, pp. 2743-2785.

Gabb, T. P., Bonacuse, P. J., Ghosn, L. J., Sweeney, J. W., Chatterjee, A., and Green, K. A., "Assessments of Low Cycle Fatigue Behavior of Powder Metallurgy Alloy U720," Fatigue and Fracture Mechanics: 31st Volume, ASTM STP 1389, G. R. Halford and J. P. Gallagher, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 110-127

Kalluri, S. and Bonacuse, P. J., "An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy," Journal of ASTM International, Vol. 7, No. 4, 2010, Paper ID JAI 102717

Kalluri, S. and Bonacuse, P. J., "A Data Acquisition and Control Program for Axial-Torsional Fatigue Testing," Applications of Automation Technology to Fatigue and Fracture Testing, ASTM STP 1092, A. A. Braun, N. E. Ashbaugh, and F. M. Smith, Eds., American Society for Testing and Materials, Philadelphia, 1990, pp. 269-287

Kalluri, S., Bhanu Sankara Rao, K., Halford, G. R., and McGaw, M. A., Deformation and Damage Mechanisms in Inconel 718 Superalloy, Superalloys 718, 625, 706 and Various Derivatives, E. A. Loria, Ed., The Minerals, Metals & Materials Society, Warrendale, PA, 1994, pp. 593-606.

Kalluri, S., Calomino, A. M., and Brewer, D. N., Comparison of Elevated Temperature Tensile Properties and Fatigue Behavior of Two Variants of a Woven SiC/SiC Composite, Ceramic Engineering and Science Proceedings, Vol. 26, Issue 2, Proceedings of the 29th International Conference on Advanced Ceramics and Composites – Mechanical Properties and Performance of Engineering Ceramics and Composites, Edgar Lara-Curzio, Ed., Dongming Zhu and Waltrud M. Kriven, General Eds., pp. 303-310, 2005.

Consulting
This section is under construction

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Core Discipline - Applied Mechanics and Advanced Concepts

Customer Specific Applications
Composite Crew Module
RXL researchers conducted structural sizing study in which alternative structural concepts and materials where examined for a composite crew module (CCM). In early 2006, the NASA Engineering and Safety Center assembled a team to examine the possibility of an alternative composite-dominated CM (Crew Module) design. As part of this activity, NASA Glenn Research Center RXL personnel took the lead on designing and sizing a potential monocoque CM concept and performed sizing analysis on a geometrically stiffened CM concept designed by the NASA Ames Research Center. A brief description of this project can be found at this link.

Cryo Tank
RXL researchers performed a number of studies aimed at identifying key design variables and structural concepts for cryogenic tank structures; with the goal of developing advanced, integrated multifunctional, lightweight composite tanks for liquid Hydrogen (LH2) Storage that weigh 25-30% less than current configurations.Because of its high specific energy content and near zero harmful emission, liquid hydrogen (LH2) is emerging as a possible fuel for these propulsion systems. A large, lightweight, reusable cryogenic liquid storage tank that can store fuel for several days would be needed for LH2 Unmanned aerial vehicles (UAVs). LH2 storage tanks have many challenges and design issues. A brief description of this project can be found at this link.

External Tank Foam Analysis and Modeling
Researchers are developing accurate models to describe the mechanical behavior of the Space Shuttle's External Tank foams under all possible thermal and mechanical environments that may be encountered prior to and during launch. In October 2005, the NASA Engineering and Safety Center (NESC) assembled an inter-center team with members from the NASA Glenn Research Center MLPB, NASA Kennedy Space Center, NASA Marshall Space Flight Center, NASA Johnson Space Center's White Sands Test Facility (WSTF), and NASA Langley Research Center to address the issue of ice liberation on external tank bracket and feed lines due to launch loads. The debris threat that ice poses is a significant concern. A brief description of this project can be found at this link. Another example is provided here where the analysis and modeling methods developed for evaluating external tank foam was discussed.

Lattice Block Construction
Researchers have been experimentally measuring the performance of lattice block panels. Superalloy lattice block panels are composed of thin ligaments arranged in three-dimensional triangulated trusslike structures. Optionally, solid panel face sheets can be formed integrally during casting. In either form, lattice block panels can easily be produced with weights less than 25 percent of the mass of a solid panel. Structural Benchmark Testing of Superalloy Lattice Block Subelements Completed. A multitude of benchmark tests on superalloy lattice block structural specimens gave promising results for this new high-performance material system that utilizes alloys with a 50-plus-year history in gas turbine engine use. The testing was performed in-house at the Structural Benchmark Test Facility within the MLPB, where the subelement-sized beam specimens were loaded at room and elevated temperatures to observe their elastic and plastic behavior, strength, and fatigue resistance. See the following links for more information:
http://www.grc.nasa.gov/WWW/RT/2003/5000/5920krause1.html
http://www.grc.nasa.gov/WWW/RT/RT2002/5000/5120whittenberger.html
http://www.grc.nasa.gov/WWW/RT/2003/5000/5920krause2.html

Flywheels and Momentum Wheels
Researchers have identified new performance index for design of gyroscopes and composite flywheels. Gyroscopes use the conservation of angular momentum in order to measure or control orientation. Often referred to as control momentum gyroscopes (CMGs), these systems are used extensively in aircraft, satellites, spacecraft, and ships. A key component of a gyroscope is the momentum wheel, also sometimes referred to as the CMG rotor. It is this spinning component that stores the angular momentum that can be used by the system for control or sensing purposes and thus drives the design of the gyroscope system.
In 2005, the Naval Research Laboratory solicited researchers from the NASA Glenn Research Center and the Ohio Aerospace Institute (OAI) within RXL to perform an analytical stress analysis, applicable to both composite (anisotropic) and metallic (isotropic) gyroscope momentum wheels. The stress analysis was combined with an anisotropic failure criterion to enable the failure (rupture) prediction of the momentum wheel due to angular velocity and gimbals maneuver loads. A factor of safety was incorporated, and a sizing (optimization) procedure was developed and implemented in a computer code. A brief project description can be found here. Time-Dependent Material Data Essential for the Durability Analysis of Composite Flywheels Provided by Compressive Experiments. The experiments proformed provided unique design data essential to the safety and durability of flywheel energy storage systems for the International Space Station and other manned spaceflight applications. Analysis of the experimental data demonstrated that the compressive stress relaxation of composite flywheel rotor material is significantly greater than the commonly available tensile stress relaxation data. Durability analysis of compression preloaded flywheel rotors is required for accurate safe-life predictions for use in the International Space Station. For more, see this link.

Composite Overwrapped Pressure Vessels (COPV) Safety Issues
Researchers are establishing a reliable flight rationale that will ensure the reliability of the individual as well as the system of composite overwrapped pressure vessels on the Space Shuttle. The NASA Glenn Research Center MLPB members have lead the effort in designing experiments and specifying test requirements for a series of full-scale vessel tests to be conducted on the Centaur and the space shuttle Orbital Maneuvering System flight hardware. The work was directed by the Orbiter Projects Office as part of a concerted effort to certify shuttle composite overwrap pressure vessel (COPV) flight hardware for the remaining mission schedule. See this link for more information.

Multifunctional Structural Concepts
RXL researchers are investigating novel multifunctional concepts – concepts which include the management of 1) structural and thermal loads, 2) acoustic noise, 3) vibration damping, 4) micrometeoroid protection 5) environmental issues and/or 6) radiation (GCRs as well as SPEs) shielding as well. The objective being the development of significantly lighterweight high performance structures. Integrated structural concepts most likely will include unitized fiber reinforced foam sandwiched construction (e.g., Webcore), the use of lattice block or other constructions which enable liquid containment features.

Turbine Blades
Ceramic Matrix Composite Vane Subelements Tested in a Gas Turbine Environment Vane subelements were fabricated from a silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC) composite and were coated with an advanced environmental barrier coating (EBC). So that the critical design features of a turbine airfoil could be addressed, the vane subelement geometry was derived from an aircraft engine vane. A fabrication technique was developed that enables vanes to be constructed using a high-strength silicon carbide fiber in the form of woven cloth. A unique cloth configuration was used to provide continuous fiber reinforcement at the sharp trailing edge, the most challenging feature for fabrication from a continuous-fiber-reinforced composite.

Sandwich Panels
Stainless-Steel-Foam Structures Evaluated for Fan and Rotor Blades. The goal of this project was to use a sandwich structure design, consisting of two stainless-steel face sheets and a stainless-steel-foam core, to fabricate engine fan and propeller blades. RX personnel studied a possible low-cost alternative to the current technologies: a stainless-steel sandwich structure encasing a stainless-steel-foam core. The face sheets provide structural strength and resistance for the blade, whereas the foam core decreases the overall density, increases vibrational and acoustic damping, maintains face sheet separation, and enhances stiffness. The use of a commercially available aerospace stainless steel and commercial manufacturing methods is expected to produce fan, propeller, and rotor blades that can be manufactured at low cost yet have mechanical properties and densities equivalent to those of currently used designs. Thus, the new design approach could yield a new generation of low-cost, low-density fan blades with performance equal to or better than that of blades produced by conventional manufacturing processes.

Vibration Characteristics Determined for Stainless Steel Sandwich Panels With a Metal Foam Core for Lightweight Fan Blade Design . The goal of this project was to provide fan materials that are safer, weigh less, and cost less than the currently used titanium alloy or polymer matrix composite fans. The proposed material system is a sandwich fan construction made up of thin solid face sheets and a lightweight metal foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by a foam layer. The resulting structure has a high stiffness and lighter weight in comparison to the solid face-sheet material alone. The face sheets carry the applied in-plane and bending loads. The metal foam core must resist the transverse shear and transverse normal loads, as well as keep the facings supported and working as a single unit. See this link for more details.

Ceramic Prosthetics And Medical Devices Need To Be Strong
POC: Noel N. Nemeth (216) 433-3215
If you stop to think about it, you realize the structure of the human body consists of brittle materials – bones and teeth. These complex structures primarily consist of the minerals calcium and phosphate in a form called hydroxyapatite. For human prosthetic devices it is desirable that they to mimic the traits of the natural material in the look, feel, and weight, while also maintaining excellent biocompatibility. Structures Division personnel of NASA's Glenn Research Center (GRC) have collaborated with numerous organizations in the research and development of ceramic prosthetics and medical devices. Structures Division personnel are world-recognized experts in the testing and life prediction of brittle materials. They have developed the unique CARES/Life (Ceramics Analysis and Reliability Evaluation of Structures) code that can predict the reliability of brittle material structures that undergo the complex loading the human body experiences over its lifetime. This includes not only the evaluation of the pristine strength of the part but also prediction of how the part's strength degrades over time from material fatigue. This capability enables engineers to select the best materials and to design the part for optimal reliability and function. In the area of dental materials and prosthetics NASA GRC has worked closely with Temple University, University of Florida, and Baylor University. In the area of medical devices GRC is collaborating with The Cleveland Clinic to develop robust drug delivery microsystems. These devices are fabricated from brittle materials such as silicon or silicon carbide – hence brittle material design rules must be used to optimize the structures strength and performance.

Fatigue
1. The cumulative fatigue behavior of a woven, melt-infiltrated SiC/SiC composite was investigated. The influence of R-ratio (minimum load/maximum load in a cycle) on the fatigue life of the woven SiC/SiC composite (manufactured in September 1999 and designated as N22) was initially established by conducting fatigue tests at R-ratios of 0.05 and 0.50. A brief description of this work can be found at
:http://www.grc.nasa.gov/WWW/RT/2005/RX/RX17L-kalluri.html

2. Effects of High-Temperature Exposures on the Fatigue Life of Disk Superalloys Examined. The purpose of this study was to examine the effects of extended exposures and extended cycle periods on the fatigue resistance of two disk superalloys. Fatigue specimens were fully machined and exposed in air at temperatures of 650 to 704 °C for extended times. Then, they were tested using conventional fatigue tests with a total strain range of 0.70 percent and a minimum-to-maximum strain ratio of zero to determine the effects of prior exposure on fatigue resistance. Subsequent tests with extended dwells at minimum strain in each fatigue cycle were performed to determine cyclic exposure effects.
http://www.grc.nasa.gov/WWW/RT/2004/RM/RM12M-gabb.html

3. Major Effects of Nonmetallic Inclusions on the Fatigue Life of Disk Superalloy Demonstrated. See
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5120gabb.html

4. Distribution of Inclusion-Initiated Fatigue Cracking in Powder Metallurgy Udimet 720 Characterized. In the absence of extrinsic surface damage, the fatigue life of metals is often dictated by the distribution of intrinsic defects. In powder metallurgy (PM) alloys, relatively large defects occur rarely enough that a typical characterization with a limited number of small-volume fatigue test specimens will not adequately sample inclusion-initiated damage. Counter intuitively, inclusion-initiated failure has a greater impact on the distribution in PM alloy fatigue lives because they tend to have fewer defects than their cast and wrought counterparts. Although the relative paucity of defects in PM alloys leads to higher mean fatigue lives, the distribution in observed lives tends to be broader. In order to study this important failure initiation mechanism without expending an inordinate number of specimens, a study was undertaken at the NASA Glenn Research Center where known populations of artificial inclusions (seeds) were introduced to production powder. See
http://www.grc.nasa.gov/WWW/RT/2003/5000/5920bonacuse.html

5. Fretting Fatigue of Gamma TiAl Studied. Gamma titanium-aluminum alloy (g-TiAl) is an attractive new material for aerospace applications because of its low density and high specific strength in comparison to currently used titanium and nickel-base alloys. Potential applications for this material are compressor and low-pressure turbine blades. These blades are fitted into either the compressor or turbine disks via a dovetail connection. The dovetail region experiences a complex stress state due to the alternating centrifugal force and the natural high-frequency vibration of the blade. Because of the dovetail configuration and the complex stress state, fretting is often a problem in this area. Although only preliminary, the results suggest that TiAl has sufficient fretting resistance to withstand the wear in dovetail applications. See
http://www.grc.nasa.gov/WWW/RT/RT2002/5000/5920lerch1.html

6. Ti-48Al-2Cr-2Nb Evaluated Under Fretting Conditions. See
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5160miyoshi.html

7. γ-TiAl Shown To Have Sufficient Durability To Allow the Design of a Robust Low-Pressure Turbine Blade. The ballistic impact resistance and remnant fatigue strength of ABB-2 was determined and compared with Ti-48Al-2Cr-2Nb. Defect size played a large role in determining critical fatigue loads.
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5120draper.html

Fracture Mechanics
The following four examples illustrate the type of experimental and analytical fracture work branch members have conducted for our aeronautic and space customers over the years. Note often times branch members team with other branch members within the Structures and Material Division to capitalize on other material discipline strengths available within the Division. Multidisciplinary teaming is just one of the many advantages of working with personnel from the Structures and Materials Division at GRC.

1. Applicability of Fracture Mechanics to Foams Examined. The primary purpose of the foam on the space shuttle's external tank (ET) is to provide thermal insulation. Although the foam has been successful in this function, it has not been without problems. Specifically, since the catastrophic loss of the Space Shuttle Columbia, which was determined to be caused by a piece of foam debris, understanding foam shedding mechanisms has become of paramount importance. Consequently, the Mechanics and Lifing Branch at the NASA Glenn Research Center was asked by the ET Program Office at the NASA Marshall Space Flight Center to help improve the thermostructural models for the foam. A brief description of this project can be found at:
http://www.grc.nasa.gov/WWW/RT/2006/RX/RX36L-lerch.html

2. Relationship Between Microstructure and Hold-Time Crack-Growth Behavior in Nickel-Based Superalloys Investigated. A well-controlled study was performed within RXL (the MLPB) to determine the variables that influence the hold-time crack-growth resistance of two newly developed powder-metallurgy superalloys; Alloy 10 and ME3. The effects of both compositional changes and variation in heat treatments were investigated. The results indicate that significant changes in the alloy's composition did not have an appreciable effect on hold-time crack-growth resistance, provided that the heat treatment remained constant. For more details see:
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX28L-telesman.html

3. Crack-Driving Forces Investigated in a Multilayered Coating System for Ceramic Matrix Composite Substrates. For more details see:
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX19L-ghosn.html

4. Life-Prediction Parameters of Sapphire Determined for the Design of a Space Station Combustion Facility Window. To characterize the stress corrosion parameters and predict the life of a sapphire window being considered for use in the International Space Station's Fluids and Combustion Facility, researchers at the NASA Glenn Research Center conducted stress corrosion tests, fracture toughness tests, and reliability analyses. Standardized test methods, developed and updated by the author under the auspices of American Society for Testing and Materials, were employed. One interesting finding was that sapphire exhibits a susceptibility to stress corrosion in water similar to that of glass. In addition to generating the stress corrosion parameters and fracture toughness data, closed-form expressions for the variances of the crack growth parameters were derived. The expressions allow confidence bands to be easily placed on life predictions of ceramic components. For more details see:
http://www.grc.nasa.gov/WWW/RT/RT2002/5000/5920salem2.html

MEMS
Designing for Strength when Things Get Small
Branch researchers are developing technologies to enable the design and fabrication of MEMS devices with optimum performance and reliability. A Step Made Toward Designing Microelectromechanical System (MEMS) Structures With High Reliability. The mechanical design of microelectromechanical systems-particularly for micropower generation applications-requires the ability to predict the strength capacity of load-carrying components over the service life of the device. These microdevices, which typically are made of brittle materials such as polysilicon, show wide scatter (stochastic behavior) in strength as well as a different average strength for different sized structures (size effect). These behaviors necessitate either costly and time-consuming trial-and-error designs or, more efficiently, the development of a probabilistic design methodology for MEMS. Over the years, the NASA Glenn Research Center's Life Prediction Branch has developed the CARES/Life probabilistic design methodology to predict the reliability of advanced ceramic components. In this study, done in collaboration with Johns Hopkins University, the ability of the CARES/Life code to predict the reliability of polysilicon microsized structures with stress concentrations is successfully demonstrated [link].

Probabilistic Fracture Strength of High-Aspect-Ratio Silicon Carbide Microspecimens Predicted
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX13L-nemeth.html
CARES/ Life Used for Probabilistic Characterization of MEMS Pressure Sensor Membranes
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5920nemeth.html

Failure Analysis
Branch personnel have been called upon numerous times to use their expertise to investigate failures within and outside the agency. The following are but a few examples of these failure analyses studies.

Ply Lifting in Reusable Solid Rocket Motor (RSRM) Nozzle Insulation
Researchers are developing models to describe the complex physics and thermo-mechanical response behavior of the Space Shuttle's RSRM nozzle insulation, an ablative liner that is exposed to extreme temperature and heating rates during motor operation.

Ply Lifting in RSRM Nozzle Insulation
Team Lead: Dr. Roy M. Sullivan
Researchers in the Structures Division of the NASA's Glenn Research Center are playing a key role in the investigation of the ply lift phenomena in the Space Shuttle's Reusable Solid Rocket Motor (RSRM) nozzle insulation. The Space Shuttle's RSRM nozzle is insulated from the hot exhaust gases by an ablative liner, fabricated with a carbon fabric-reinforced phenolic resin composite. The carbon cloth phenolic (CCP) composite is constructed through a tape wrapping process, resulting in a laminated CCP ablative liner. Ply lifting is a type of sub-surface de-lamination where the plies are lifted and separated resulting in a distinct S-shaped pattern to the de-laminated plies. During motor operation the CCP liner is exposed to extreme temperatures and heating rates. These extreme environments occasionally cause ply lifting during motor operation. The flight safety concern is that the lifted plies (as well as the insulation layer above the lift) will be washed away by the high velocity exhaust gas flow, resulting in accelerated erosion of the liner. Accelerated erosion may lead to a violation of the flight safety factors and potentially a catastrophic loss of a booster nozzle.The forces inside the material that lead to the ply lift phenomena are still not fully-characterized. GRC's role in the ply lift investigation is to develop mathematical models to describe the complex physics and thermo-mechanical response behavior of the CCP as it's rapidly heated to high temperatures. These models will help to isolate the exact stress and strain states responsible for ply lifting and to help direct material and design changes to reduce the propensity for ply lifting. Inspection of gears from Space Shuttle flight units revealed unexpected damage to the gear working surfaces. Working as part of the NASA Safety Engineering Center's (NESC) Independent Assessment Team, a project was executed to determine whether or not gears with defined levels of damage were fit for service. Consequently, project objective was to establish the root cause of the damage and to replicate the damage on gear test specimens. Experiments were done using NASA Glenn Research Center's Spur Gear Test Rigs, which were specially modified for this project. A brief description of work can be found at the following link:
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX56M-krantz.html

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Customers

Aeronautics (ARMD)
The branch receives approximately 55% of its support from the NASA Aeronautics Research Mission Directorate (ARMD), see http://www.aeronautics.nasa.gov/index.htm. Consequently, we are focused on providing high quality research and technology support to the following fundamental aeronautic (FAP) and aviation safety (AVSP) programs.

Fundamental Aeronautic Program (FAP)
Hypersonics Project
Supersonics Project
Subsonic Fixed Wing (SFW) Project
Subsonic Rotary Wing (SRW) Project
Aviation Safety Program (AvSP)
SSAT
VSST RHD

Industry
The branch receives approximately 5% of its operating budget from its industrial customers. However, many of the collaborations undertaken are done on an in-kind basis with significant support coming from either the Aeronautic and/or Space Mission Directorates. Typically, these collaborations are conducted under a Space Act Agreement (SAA) which clearly spell out each parties responsibilities and deliverables. The following list indicates the variety of industrial customers we provide research and technology services to:

• Aerojet
• Aerospace Corp.
• AlliedSignal
• Allison
• ANSYS Inc
• Boeing
• Carborundum
• Caterpillar
• Cega
• Chrysler
• Corning
• Collier R&D
• DEC
• Detroit Diesel
• Eaton
• ESA
• Ford
• General Electric Aviation (GEAE)
• General Motors
• Grumman
• GTE
• Hughes
• Intel
• Johnson & Johnson
• Kyocera
• Lanxide/DuPont
• Lockheed-Martin
• Norton
• Philips
• Poco
• PPG
• Pratt & Whitney
• Rocketdyne
• Rolls-Royce
• Solar Turbines
• Sundstrand
• TRW
• United Technologies
• Westinghouse

Space
The branch receives approximately 40% of its support from the various NASA Space Mission Directorates (ESMD, SOMD, and SMD). Consequently, we are focused on providing high quality research and technology support to the following programs:

Exploration (ESMD)
Ares I-1 J-2X, CEV Radiator, Digital Astronaut Program (Bone Remodeling and Human Physiological Modeling)

Shuttle Operations (SOMD)
ET Foam, ET Ply Lifting, Tile Analysis, Window Analysis, GFE Stress Analysis

Science (SMD)
Stirling Engine - RXL activities have revolved around conducting the durability and life tests for the Stirling Radiosotope Generator (SRG), see the following links for some specific examples of how we have helped our space science customer:
http://www.grc.nasa.gov/WWW/RT/2006/RX/RX31L-krause1.html
http://www.grc.nasa.gov/WWW/RT/2006/RI/RIO-abdul-aziz.html
Long-Term Structural Benchmark Testing Started for Stirling Convertor Heater Heads:
http://www.grc.nasa.gov/WWW/RT/2005/RX/RX32L-krause.html
Benchmark Calibration Tests Completed for Stirling Convertor Heater Head Life Assessment:
http://www.grc.nasa.gov/WWW/RT/2004/RS/RS02L-krause2.html

NESC
COPVs
All Composite Crew Module (CCM)

University/Government
The branch interacts with Universities and other Government Agencies on various projects of mutual interests. Many of these collaborations are undertaken on an in-kind basis with significant support coming from either the Aeronautic and/or Space Mission Directorates. Typically, these collaborations are conducted under a Space Act Agreement (SAA) which clearly spells out each party's responsibilities and deliverables. The following list indicates a number of our recent partners which we provided research and technology services both analytical and experimental to:

Colleges & Universities:
• Ohio State University (OSU)
• University of Akron
• University of Michigan
• Arizona State University (ASU),
• Mississippi State University
• Stanford University

DOD:
• USAF – Wright Patterson Air Force Base (WPAFB)
• Army Research Lab (ARL)
• Naval Research Lab (NRL)
• NSWC
DOE
• Oak Ridge National Laboratory (ORNL)
• Los Alamos National Laboratory (LANL)
NIST

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Themes

Multicale Composite Modeling Center of Excellence
Mission
Develop, integrate, and validate physics-based models and the associated multiscale computational design, analysis, and optimization tools (spanning multiple length and time scales) required to make these models accessible to the engineering and material science communities.

What is multiscale analysis?
An analysis transcends (moves up) or descends (moves down) length scales using homogenization and localization techniques, respectively; where a homogenization technique provides the effective properties or equivalent response of a "structure" (higher level) given the properties or response of the structure's "constituents" (lower scale). Conversely, localization techniques provide the response of the constituents given the response of the structure. Multiscale analysis involves at least two such homogenizations /localizations among at least three scales. During a multi-scale analysis, a particular level in the analysis procedure can function on both scales simultaneously.

For example, X and Y (level 1) are homogenized to obtain properties for V (level 2), while V and W are homogenized to obtain the properties or response of U (level 3). V is thus both a "structure" and a "constituent" depending upon whether you're looking at level 1 or 3 respectively. Obviously, the ability to homogenize and localize accurately requires a sophisticated theory that relates the geometric and material characteristics (salient features) of structure and constituent.

Testing Facilities
MACE resides in the Structures and materials Division at NASA Glenn Research Center, with access to state-of-the-art thermo-mechanical testing facilities. This is critical as model development and experimentation are highly coupled, for example, exploratory tests are needed to identify mechanisms and key features; characterization tests are needed to determine model parameters; and validation tests are needed to evaluate models and identify shortcomings.

Glenn established MACE since its micromechanics capabilities lay at the crossroads of design, analysis, and optimization of materials and structures.

Visit the MACE website

High Temperature Deformation and Damage Modeling
The solution of a solid mechanics problem involves the establishment of a statically admissible field (one which satisfies equilibrium internally and tractions boundary conditions), a kinematically admissible field (satisfaction of strain-displacement relations and displacement boundary conditions) and the satisfaction of material constitutive laws. Constitutive theory (laws) concerns the mathematical modeling of the physical response (output) of a material to a given stimulus (input); that input can be a generalized force or displacement. The importance of accurate constitutive relationships is illustrated in Figure 1; as they form the primary link between stress (σij) and strain (εij) components at any point within a body.

These relations may be simple (as in the case of linear elasticity) or extremely complex (as in the case of viscoplasticity) depending upon the material comprising the body and the conditions to which the body is subjected (e.g. temperature, loading, environment). Constitutive relations for a particular material are determined experimentally, and they may involve both physically (directly) measurable quantities (e.g. strain, temperature, time) as well as non-directly measurable internal parameters often referred to as internal state variables.

The actual behavior of real materials to thermal and mechanical stimuli can vary greatly depending upon the magnitude and multiaxiality of loading and the magnitude of the homologous temperature (TH = T/Tm). For example at room temperature material response is typically time-independent and either reversible (i.e., linear elastic) or irreversible (inelastic) depending upon whether or not the yield stress of the material has been exceeded. Alternatively, when TH > 0.25 time-dependent behavior, both reversible and irreversible, can be commonly observed as illustrated schematically in Figure 2, wherein i) strain rate sensitive , ii) creep, iii) relaxation, iv) thermal recovery, v) dynamic recovery and vi) creep/plasticity interaction response behavior are all shown. Other complex time and path dependent behavior such as cyclic ratcheting, creep/fatigue interaction, thermal mechanical fatigue are also often times observed depending upon the magnitude and type of loading (e.g., thermal or mechanical) being applied.

A prerequisite for meaningful assessment of component durability and life, and consequently design of structural components, is the ability to accurately predict the stress and strains occurring within a loaded structure, composed of a given material. As constitutive material models (be they simple or complex) provide the required mathematical link between stress and strain, this necessitates the development and characterization of an appropriate constitutive behavior model for any material before that material can be certified for use by a designer. Thus constitutive models with varying levels of idealizations have been proposed and utilized, each with its own shortcomings/limitations. For more information on the type of constitutive models the Mechanics and Life Prediction Branch are researching and how branch experts can help you with your specific issue(s) please visit the "Core Disciplines - Analytical & Computational Mechanics" section of this site.

Exploratory, Characterization and Validation Testing
Experimental tests are conducted for a number of reasons. For structural materials, we wish to know the behavior of each material, develop a model to describe its behavior, and verify that the model provides accurate and reliable predictions for service conditions. Furthermore it is important to document the limitations of the model such so that the model is not used blindly, yielding errors and causing unexpected failures to the structure. Other types of testing such as screening tests can be run to describe material behavior for use in alloy development. These simple tests would be conducted on variations of the material, be it varying compositions, heat treatments, or various processing conditions to guide improvements in future materials. Finally, very specific tests can be conducted to examine certain issues of the structure. For example, cyclic loading of individual gear teeth can be performed to yield insight into tooth reliability, and to set load-life limits for service.

The Mechanics and Life Prediction Branch specializes in developing and utilizing test methods for extreme environment testing of materials and sub-components to support the rational formulation of constitutive equations. Three types of experimentation are typically necessary: Exploratory, Characterization, and Verification.

Exploratory Testing
The purpose of exploratory testing is to map out various regimes of interest, illuminate the salient material response (e.g., time dependence/time-independence, sensitivity to hydrostatic stress field, material symmetry and/or anisotropy, etc.), identify fundamental deformation and damage mechanisms and guide the mathematical structure of the model. It is assumed that within any regime of interest the deformation and damage mechanisms remain constant, and can therefore be described by a mathematical model. Through this testing the mechanisms of importance in these regimes are documented and the boundaries defined. The regimes can then be incorporated into the mathematical framework of the model, which will be capable of describing the material behavior in these areas. A typical example of this is to probe into the inelastic regime to map out the yield surface. A model can then be developed which involves either isotropic or kinematic hardening, or even a combination of both. Likewise, if there is significant oxidation above a certain temperature, severe enough that it significantly degrades the material life, then a time dependent mechanism must be included to capture this degradation.

Characterization Testing
Once the framework for the model is complete, testing begins to fully characterize the model parameters. This is the most common stage of testing. Generally, tests are conducted on simple coupons and under uniaxial load conditions. The reason for these simple tests is to have complete control of the stress and strain state within the material, and to be able to calculate them through simple equations. These tests generally contain a large volume of material subjected to constant deformation and damage within the gauge section, which can be analyzed in a post-test forensic analysis, giving additional information to the mechanisms taking place in that particular regime. During characterization testing a large number of tests are conducted to define the constants associated with each mechanism in the model. Emphasis is placed on covering a wide range of test conditions to allow a thorough characterization. Repeats are performed to give insight into variability resulting from both material and experimental scatter. Multiple material lots can also be incorporated. If desired the model can be adapted to include probabilistic properties. The amount of testing performed in this section is dictated by a compromise between the accuracy desired in the model and the cost and time associated with conducting more tests. The desired outcome of characterization testing is to produce a model that can be used with confidence over the service range of conditions. Moreover, the model should be sufficiently robust that extrapolation of properties beyond those generated in the test program can be handled with reliability. Branch personnel perform such test regularly and therefore can provide expert advice to minimize the amount of testing and maximize the benefits of such testing.

Verification Testing
Once a reliable model is in hand and fully characterized, testing is conducted to verify its accuracy. While the majority of the exploratory and characterization testing is performed on simple coupons, verification testing is usually done on test samples that are more representative of the service components. These can be simple shapes (plates, beams, and shells), subelements, subsized components, or actual components. The stress state is usually more complex than in the previous two forms of testing, and is often multiaxial in nature.

The drawback to this form of testing is that the stress and strain state is often non-uniform throughout the body and frequently requires a finite element analysis to understand them. Another problem associated with this type of testing is the large cost of the test sample, the myriad of instrumentation associated with the test, and the testing itself. However, this type of testing is necessary to gain confidence in the model and if necessary provide feedback for subsequent developmental and/or refinement efforts associated with the given model. For example the most common deficiency is usually the activation of some unanticipated damage mode that the characterized model was not designed to handle.

To find out more information about the multiple world-class experimental research facilities within the Mechanics and Life Prediction Branch that are designed to evaluate the full breadth of material behaviors under the extreme loading conditions and environments typical in aerospace propulsion applications please visit the "Core Disciplines - Material Characterization and Experimental Mechanics" section of this site.

Materials Application in Extreme Environments
This section is under construction.

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