Bell-shaped proportional viscous damping models with adjustable frequency bandwidth

Abstract

A proportional viscous damping model based on a bell-shaped basis function parameterized by the frequency and damping ratio at its peak has recently been proposed. The basis function in the frequency domain has a fixed frequency bandwidth and could not match a damping ratio curve that changes precipitously over a short frequency interval. This study proposes new parameters to control the bandwidth, while maintaining the sparsity of damping coefficient matrix and the order of computational efficiency. Three types of modification are introduced. Types 1 and 3 control the bandwidth while maintaining the symmetry of the bell shape on the logarithmic scale, and Type 2 allows the left and right bandwidths to be adjusted independently. Type 3 controls the bandwidth while maintaining the same number of nonzeros in the expanded damping matrix, but the other two have the number of nonzeros increased for a smaller bandwidth. These modifications make the model versatile in matching any smooth damping ratio curve, particularly for a curve that has damping ratios changing drastically over a short frequency interval. Several examples are given to showcase their matching performance and the sparsity of their expanded damping coefficient matrices.