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Dynamic Model Verification of Large Structural Systems
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Sector:
Event:
Aerospace Meeting
Language:
English
Abstract
Finite element models of large structural systems, such as the Space Shuttle or its major components, may contain thousands of finite elements with tens of thousands degrees of freedom. Dynamic analysis to predict structural frequencies and mode shapes is performed after transforming the mass and stiffness matrices, through a series of static reductions, to a reduced set of coordinates which still may include several hundred degrees of freedom. The objective of the present methodology is two-fold: (1) to process test data obtained from either modal survey tests, or slow sine-sweep tests, to extract a set of orthogonal modes best matching the test data while being commensurate with the dynamic model, and (2) to modify submatrices of the dynamic model mass and stiffness matrices to adjust the model to best fit the test data.
The method has been implemented using a linear statistical sequential estimator for computation on a CDC computer. Demonstration problems involving Space Shuttle Quarter-Scale vibration test data and dynamic models have been run. This paper will discuss the general methodology and experience to date.
Citation
Lee, L. and Hasselman, T., "Dynamic Model Verification of Large Structural Systems," SAE Technical Paper 781047, 1978, https://doi.org/10.4271/781047.Also In
References
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- Garba J.A. Wada B.K. “Application of Perturbation Methods to Improve Analytical Model Correlation with Test Data,” 1977 SAE Aerospace Meeting Sept. 1977
- Rockwell International - Space Division “Quarter-Scale Orbiter, Modal Test, Data Files for Symmetric Modes,” 1978
- Barrett J.A. Ujihara B.H. “Verification Analysis Report of Quarter-Scale Ground Vibration Test, Orbiter Element Soft Mounted,” Rockwell International Report SD77-SH-0244 Oct. 1977