Modal Damping Identification for Flexible Structures by Time Series Model Method

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In this report, a new technique for damping estimation for flexible structures such as robot arms, space structure elements and long spanned pipings is proposed.The method basically utilizes a stochastic time series model like Autoregressive (AR) model and Autoregressive and Moving-average model. In contrast with the former major methods mainly discussed in the frequency domain, the technique proposed here is a "stochastic time domain technique". It has a significant advantage for the estimation of fundamental modal damping of flexible structures in various industrial facilities and structures under random excitations such as earthquake excitations and micro tremors.Using simple systems like SDOF system and Two-Degree-of-Freedom system subjected to random excitations, the applicability of this technique is examined. It has been also made clear that the technique is particularly effective for the case when the total number of data to be analyzed has to be limited.Finally, the study demonstrates the applicability of this method for the flexible piping system having quite light damping values.