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Substantial effort has been expended in attempts to estimate dynamic response parameters of structures, damping ratios have been estimated with varying degrees of success. A portion of hte effort has been motivated by active research and development of structural integrity monitoring systems. for design purpose, accurate estimates of damping ratios are important.
In our work, the spectral shape of the response near the natual frequency is estimated first as the basis for further analysis. Hal-fpower bandwidth and spectral moments are derived fromt he spectral shape. The bandwidth and moments are directly related to the damping ratio. Such as, a iterated method for obtaining the damping ratio from the spectral moments has been proposed by S. S. Sunder 1985. The 1/2 power bandwidth and moments are one of the cruial part of the method. The other part is the estimation of the spectral shape. There are many methods to estimate the spectral shape. Different combinations of the two parts give varieddamping ratios. In our paper, we are trying to identify the better combinations. We use many sets of exact and simulated data and apply many different combinations. Results show that the MEM spectral method and the method by Sunder is the best among all combination in our test. All input spectra are assumed smooth near the natural frequency.
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