Test-Analysis Correlation of the Single Stringer Bending Tests for the Space Shuttle ET-137 Intertank Stringer Crack Investigation

摘要

Following the scrub of the November 5, 2010 launch attempt of Space Shuttle mission STS-133, cracks were found in the stringers on the Intertank of the External Tank, ET-137. A large investigation was conducted to determine the root cause of the cracks, establish a repair for the stringers, and provide data for the flight readiness assessment of the repaired tank. As part of the investigation, static load tests of individual stringer-skin sections and corresponding finite element analyses were performed. The details of these finite element analyses and the test-analysis correlation for these single stringer bending tests are presented. Comparisons and contrasts between the analyses and test results for two specific stringers are made and used to discuss challenges related to modeling for quickly-developed test programs; correlation of the finite element models to the test data was not trivial and is discussed. The analyses and test results are also discussed as they related to the development of the flight-worthiness rationale for ET-137 and the tanks for the remaining Shuttle missions. Lessons learned are identified.