Study on Experimental Identification and Alternative Kernel Functions of Nonviscous Damping

Abstract

Nonviscous damping is represented by the convolution integral of the time history velocity and kernel function. Nonviscous damping model may correctly represent the energy dissipation character of the linear system for the multiple-choice kernel functions. This paper outlines a procedure for identifying relaxation parameter and damping ratios of the cantilever beams with nonviscous damping in time domain. In the procedure, the approximate value of the relaxation parameter and damping ratios can be identified by the continuous wavelet transform (CWT) firstly. Then the natural frequency of the tested structure can be obtained through the eigensystem realization algorithm (ERA). Finally, the relaxation parameter and damping ratios are identified through the sensitivity method by using the approximate initial values from the CWT and the natural frequency from the ERA. The proposed identification procedure can identify the parameters of the numerical example with a small error. Then, the displacement of cantilever beams measured from experiment is used in the identification procedure. It shows that good estimates can be obtained from the procedure by choosing suitable kernel function. Identification results for nonviscous damping beams with four different kernel functions are discussed. The suitable kernel function can be obtained through the analysis of the identification results. As for the result, this paper analyzes the causes, and presents relevant suggestions for recommended kernel functions. The research on nonviscous damping will increase the application of nonviscous damping model in the dynamic analysis of actual structures.