AVERAGE POWER RATIO METHOD FOR DAMPING ESTIMATION

摘要

The well known bandwidth method is probably the simplest one for the damping estimation. By using the half-power bandwidth formula, the damping factor is estimated to be the half value of the bandwidth at the half-power points. Other values of power ratio, two thirds or four fifths for example, can also be selected for not well separated modes. This method is quite efficient for simple model test cases. However the determination of the two frequencies which correspond to a selected power ratio value is not a convenient task. In this paper, an average power ratio method is suggested. The average value of power ratio is calculated at two frequencies symmetrically located from the peak amplitude frequency. Then the damping can be estimated by using a formula similar to that of the power bandwidth method. In this way, the damping estimation becomes much more convenient. In addition, applications to both analytical and experimental data show that the average power ratio method provides slightly more accurate results than the power bandwidth method.