Performing a Large-Scale Modal Test on the B2 Stand Crane at NASA’s Stennis Space Center
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A modal test of NASA’s Space Launch System (SLS) Core Stage is scheduled to occur prior to propulsion system verification testing at the Stennis Space Center B2 test stand. A derrick crane with a 180-ft long boom, located at the top of the stand, will be used to suspend the Core Stage in order to achieve defined boundary conditions. During this suspended modal test, it is expected that dynamic coupling will occur between the crane and the Core Stage. Therefore, a separate modal test was performed on the B2 crane itself, in order to evaluate the varying dynamic characteristics and correlate math models of the crane. Performing a modal test on such a massive structure was challenging and required creative test setup and procedures, including implementing both AC and DC accelerometers, and performing both classical hammer and operational modal analysis. This paper describes the logistics required to perform this large-scale test, as well as details of the test setup, the modal test methods used, and an overview of the results.
KeywordsNASA Large-Scale Structure Derrick Crane Experimental Modal Analysis Hammer Impact Testing Lessons Learned
The author would like to thank Brendan Sontag and Alex McCool of NASA Marshall Space Flight Center and James Bolding and Regina Chambers of Aerie Aerospace for all their work in preparing for, setting up, and performing a very large modal test in the hot Mississippi summer weather. Additional thanks to Dana Chandler of Jacobs ESSSA in acquiring the data and performing meticulous analysis on the time histories and corresponding modal fitting. Valuable pre-test analysis and test coordination support was provided by Vinod Shekher, Moayyad Parviz, Hyoung-Man Kim, and Steve Morgan of Boeing. Finally, thanks go to Ryan Robert and Glenn Warner of NASA Stennis Space Center for their help in coordinating our testing with the B2 stand crane operations.
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