1995-05-01

A Novel Approach to Statistical Energy Analysis Model Validation 951328

Statistical Energy Analysis (SEA) is a tool for estimating the response of complex dynamic systems at high modal density. This tool is seeing ever wider application in a range of industries, including aerospace industry, marine industry, and building trades. The automotive industry is beginning to explore the application of SEA to high frequency vehicle acoustic design. The SEA model of vibrational power transmission has a direct analogy to thermal power transmission (diffusion). As thermal power flow is proportional to temperature difference, vibrational power flow is proportional to modal energy difference. In this paper the thermal analogy is exploited to visualize the SEA results. This is accomplished by color coding a finite element representation of the structure.In this paper, the thermal analogy is used to correlate test data with SEA model results. This is accomplished by constructing a test based modal power thermogram. The test based modal powers are calculated from a space averaged velocity and a space averaged drive point impedance. The drive point impedance is a representation of a mass normalized modal density. Dividing the mean square velocity by the averaged impedance results in an estimate of the energy divided by the modal density (modal power). This test derived quantity is then used to construct a thermogram in the same sense as the analytical results. The correlation of the test and analytical thermograms then insures that the desired response is correctly predicted and that the energy transfer path is also correct. This insures that the proper response is calculated and that the model is robust.This procedure is applied to a D-class trimmed body for structureborne input. The structureborne response is calculated and test and analytical thermograms are shown.

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