Energy Based Comparison of Test and Analysis Response in the Frequency Domain

Accepted modal based techniques for comparing finite element model and test data for test/analysis correlation and subsequent model updating are impossible to use in the high modal density midfrequency regime. A new approach is presented for comparing test and analysis representations using frequency-based response data instead of modal parameters. The new method uses frequency band averaging of the output power spectral densities with the central frequency of the band running over the complete frequency range of interest. The result of this computation can be interpreted in several different ways but the immediate physical connection is that it produces the mean-square response, or energy, of the system to random input limited to the averaging frequency band. The averaging process is consistent with the averaging done in statistical energy analysis for stochastic systems. The averaged response curves can be compared on a pointwise basis, or they can be compared within a running frequency band.