NASA

Columbia Shuttle Disaster Investigation

AlphaSTAR contributed to the investigation to identify the causes that lead to the loss of the Space Shuttle Columbia. The physical cause of the loss of Columbia and its crew on Feb 1, 2003 was a breach in the Thermal Protection System (TPS) on the leading edge of the left wing, caused by a piece of insulating foam which separated from the left bipod ramp section of the external tank at 81.7 seconds after launch, and stuck the wing in the vicinity of the lower half of Reinforced Carbon Carbon (RCC) panel number 8. This allowed, during re-entry, superheated air to penetrate through the leading edge insulation and progressively melt the aluminum structure of the left wing leading to the failure of the wing and breakup of the orbiter.

AlphaSTAR simulated the time dependent breakup of the leading edge during reentry using its analytical software suite GENOA. Furthermore, it simulated damage growth and fracture in impact test of RCC panel number 8. In 2004, AlphaSTAR was commended by the Columbia Accident Investigation Board for its contributions and analysis efforts.

Simulation of Structural Failure Through Re-Entry

Damage From Foam Impact on RCC Panel 8

Reference

[1] K. Bowcutt, D. Picetti, K. Yun, F. Abdi "A High-Fidelity Aero-Thermal-Structural Analysis Of The STS-107 Columbia Reentry With Postulated Wing Leading Edge Damage". JANNAF Conference Paper 2003, Colorado Spring, Colorado

Return to Flight - Failure Analysis of Shuttle Reinforced Carbon-Carbon Specimen

In support of NASA return to flight efforts, AlphaSTAR assessed the damage growth and delamination to failure in samples made from the shuttle's reinforced Carbon Carbon RCC material. AlphaSTAR provided NASA with in depth details on failure modes in short and long RCC specimens under bending loads. Photos of the interior of the failed test specimens confirmed the predicted failure behavior in that no delaminations occurred in the longer specimen, whereas primary and secondary delaminations occurred in the shorter specimen.

Failed short RCC plate specimen

Failed long RCC plate specimen

Reference

[1] V. S.. Sokolinsky, J. Housner , J. Surdenas, and F. Abdi, "Progressive Failure Analysis of Shuttle Reinforced Carbon-Carbon Plate Specimens". AIAA-2006-1789, Newport, RI, May 1-5, 2006.

Structural Evaluation of Exo-Skeletal Engine Concept

AlphaSTAR evaluated weight and structural benefits from use of composites in advanced engine concept Exo-Skeletal Engine (ESE) applications. Progressive failure analysis was used to evaluate durability, damage tolerance, and fracture of ESE composite rotor for a large subsonic engine.

Projected view of all composite advanced engine concept (Exo-Skeletal Engine ESE)

Finite element model of ESE concept

Structural damage and fracture (highlighted with red color) of composite compressor rotor under increased rotor speed