Finite element analysis can be an extremely effective design tool once a valid model of the structure is obtained. An experimentally validated model increases the confidence level in the analysis of proposed design changes. This paper shows how modal testing was used to improve the accuracy of a finite element model in predicting the resonant frequencies and corresponding mode shapes of a test fixture. Two different mounting configurations were studied. In one case, the initial finite element analysis differed by 37 percent from test results in predicting the fundamental frequency. This led to a refinement in the boundary conditions used in the finite element analysis. The resulting finite element analysis was within 2 percent of the experimental results. In the second case, the boundary conditions were such that the finite element analysis was only able to bound the test results. However, for both cases, mode shapes obtained from analytical and test methods were similar. These results show how modifications based on modal testing significantly improved the results predicted by finite element analysis.
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