A System Matrices Reduction Method for Damped Systems

In our previous work, a frequency-domain method for estimating the mass, stiffness and damping matrices of a structure was presented. In that method, the accuracy of identified system matrices for different data point configurations are addressed and shown that a more accurate damping matrix can be identified and the present method is insensitive to the data point configurations used in the identification procedure even for cases with only few data points. In this paper, a system matrices reduction method for a damped system is proposed. In this reduction method, a mapping matrix is formulated based on the original complex mode shapes and utilized to transform the original system matrices to reduced ones, which possess the selected modes of original system. The selection of active degrees of freedom is also addressed in this paper. The simulated and experimental results indicate that the reduction method is effective and accurate.