Further Developments in the Dynamic Stiffness Matrix (DSM) Based Direct Damping Identification Method

Theoretical development of a dynamic stiffness matrix (DSM) based direct damping matrix identification method is revisited in this paper. This method was proposed to identify both the mechanism and spatial distribution of damping in dynamic structures as a matrix of general function of frequency. The objective of this paper, in addition to the review of the theoretical development, is to investigate some major issues regarding the feasibility of this method. The first issue investigated is how the errors in measured frequency response functions (FRF) affect the accuracy of the DSM. It was already known that the DSM is highly sensitive to errors that are present in the FRF. A detailed analytical and computational study is conducted, which finally leads to a sound physical explanation of the high sensitivity of the DSM to measurement errors. A new and also important conclusion is that the leakage error drastically affects the accuracy of the computed DSM. The second major issue reported is the experimental implementation of the DSM based method to minimize the leakage error. Based on the findings presented in this study, a new and improved test setup is designed and developed, which enables the authors to obtain a good quality result that supports the theoretical and numerical analyses previously conducted.