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Deformation, Failure, and Fatigue Life of SiC/Ti-15-3 Laminates Accurately Predicted by MAC/GMC

NASA Glenn Research Center's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) (ref.1) has been extended to enable fully coupled macro-micro deformation, failure, and fatigue life predictions for advanced metal matrix, ceramic matrix, and polymer matrix composites. Because of the multiaxial nature of the code's underlying micromechanics model, GMC (ref. 2)--which allows the incorporation of complex local inelastic constitutive models--MAC/GMC finds its most important application in metal matrix composites, like the SiC/Ti-15-3 composite examined here. Furthermore, since GMC predicts the microscale fields within each constituent of the composite material, submodels for local effects such as fiber breakage, interfacial debonding, and matrix fatigue damage can and have been built into MAC/GMC. The present application of MAC/GMC highlights the combination of these features, which has enabled the accurate modeling of the deformation, failure, and life of titanium matrix composites (ref.3).

Graph of stress versus strain
Deformation and failure of SiC/Ti-15-3 at room temperature.
Long description

The preceding graph compares the room-temperature deformation and static life predicted by MAC/GMC with experimental data for five SiC/Ti-15-3 laminates (ref. 4). In these simulations, the Ti-15-3 matrix inelastic behavior is modeled using incremental plasticity theory (ref. 5) with piecewise linear postyield response. The SiC fiber failure behavior is modeled using Curtin's effective fiber-breakage model (ref. 6). The normal and shear fiber-matrix interfacial debonding, which allows the "knee" present in the [90°] and [±30°]s laminate1curves to be captured, is simulated with the evolving compliant interface model (ref. 7). The result of the coupling of these microscale models is the excellent macroscale agreement evident in the preceding graph.

The following graph compares the elevated-temperature low-cycle fatigue (LCF) response of the SiC/Ti-15-3 laminates predicted by MAC/GMC with experimental data (ref.8). Here, a fatigue damage model (ref. 9) was included for the matrix and the fiber (ref. 10). Again, the coupled nature of the microscale failure, debonding, and fatigue models within MAC/GMC has led to good agreement for this complex simulation.

Graph of maximum stress versus cycles to failure
Stress-controlled LCF of 35-vol% SiC/Ti-15-3 at 800°F.
Long description

References

  1. Arnold, S.M., et al.: Micromechanics Analysis Code With Generalized Method of Cells (MAC/GMC): User Guide. Version 3, NASA/TM-1999-209070, 1999.
  2. Aboudi, J.: Micromechanical Analysis of Thermo-Inelastic Multiphase Short-Fiber Composites. Comp. Eng., vol. 5, no. 7, 1995, pp. 839-850.
  3. Bednarcyk, B.A.; Arnold, S.M.; and Lerch, B.A.: Fully Coupled Micro/Macro Deformation, Damage and Failure Prediction for SiC/Ti-15-3 Laminates. NASA/TM-2001-211343, 2001.
  4. Lerch, Bradley A.; and Saltsman, James F.: Tensile Deformation of SiC/Ti-15-3 Laminates. ASTM STP 1156, 1993, pp. 161-175.
  5. Mendelson, Alexander: Plasticity: Theory and Applications. Krieger Publishing Company, Melbourne, FL, 1983.
  6. Curtin, William A.: Theory of Mechanical Properties of Ceramic-Matrix Composites. J. Am. Ceram. Soc., vol. 74, no. 11, 1991, pp. 2837-2845.
  7. Bednarcyk, Brett A.; and Arnold, Steven M.: A New Local Debonding Model With Application to the Transverse Tensile and Creep Behavior of Continuously Reinforced Titanium Composites. NASA/TM-2000-210029, 2000.
  8. Lerch, Bradley A.: Fatigue Behavior of SiC/Ti-15-3 Laminates. HITEMP Review 1990. NASA CP-10051, paper no. 35, 1990, pp. 35-1 to 35-9. (Available from the NASA Glenn Subsonic Systems Office.)
  9. Arnold, S.M.; and Kruch, S.: Differential CDM Model for Fatigue of Unidirectional Metal Matrix Composites. Int. J. Damage Mech., vol. 3, no. 2, 1994, pp. 170-191.
  10. McDowell, David L., ed.: Applications of Continuum Damage Mechanics to Fatigue and Fracture. ASTM STP 1315, 1997.

Glenn contact: Dr. Steven M. Arnold, 216-433-3334, Steven.M.Arnold@grc.nasa.gov
Authors: Dr. Brett A. Bednarcyk and Dr. Steven M. Arnold
Headquarters program office: OAT
Programs/Projects: RLV

1The letter "s" after the closing bracket indicates "symmetric."

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Last updated: June 2002

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