External tank structural impact tests being conducted in the Ballistic Impact Laboratory.
Long description of figure 1.
Following the Space Shuttle Columbia accident investigation, NASA initiated the Return to Flight program, which established numerous technical issues requiring resolution prior to the launch of STS-114. NASA Glenn Research Centerís Ballistic Impact Team was given the task of conducting numerous critical ballistic impact testing and analysis programs to investigate and quantify the physics of debris impact on the reinforced carbon/carbon wing leading edges, nose caps, orbiter windows, and external tank structures. The test programs ranged from fundamental material characterization tests to full-scale tests of the orbiter wing leading edge and nose cap, which identified critical impact damage threats to various shuttle components. Glenn researchers examined damage threats from potential impactors, including shuttle thermal-protection foams and ablators as well as ice formed on the shuttleís external tank. The analysis effort at Glenn encompassed the development of high-fidelity material models for implementation into the explicit finite-element impact-analysis code LS DYNA. The analysis method is now being used to analyze impact events on the shuttle system.
Glennís Ballistic Impact Team addressed six elements that were critical to the success of the Return to Flight program:
High-speed digital photography captures the behavior of external tank foam undergoing an impact event.
Long description of figure 2.
Each element was successfully completed on time, leading to the successful launch of STS-114 in July 2005. As a result of Glennís testing, the design of the orbiter windows was changed, the external tank was cleared as safe to fly, and a previously unavailable physics-based impact analysis capability was established for the shuttle program. As a consequence of Glenn Ballistic Impact Team contributions, mission safety for future shuttle operations increased dramatically.
Material models developed by Glennís Ballistic Impact Team were implemented into the LS DYNA impact analysis code and used to predict impact damage for future shuttle missions.
Long description of figure 3.
Melis, Matthew, et al.: A Summary of the Space Shuttle Columbia Tragedy and the Use of LS-DYNA in the Accident Investigation and Return to Flight Efforts. Prepared for the 8th International LS-DYNA Users Conference, Dearborn, MI, 2004.
Melis, M.E., et al.: A Summary of the NASA Glenn Ballistic Impact Lab Contributions to the Columbia Accident Investigation. 2005 Proceedings of the Annual Reliability and Maintainability Symposium, Alexandria, VA, 2005, pp. 284-290.Glenn contacts: Matthew E. Melis, 216-433-3322, Matthew.E.Melis@nasa.gov; and Dr. Michael Pereira, 216-433-6738, J.M.Pereira@nasa.gov
Materials and Structures
Last updated: October 10, 2006
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