Accuracy of the half-power bandwidth method with a third-order correction for estimating damping in multi-DOF systems

A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems. This paper analyzes the accuracy of the half-power bandwidth method with the third-order correction in damping estimation for multi-DOF linear systems. Damping ratios in a two-DOF linear system are estimated using its displacement and acceleration frequency response curves, respectively. A wide range of important parameters that characterize the shape of these response curves are taken into account. Results show that the third-order correction may greatly improve the accuracy of the half-power bandwidth method in estimating damping in a two-DOF system. In spite of this, the half-power bandwidth method may significantly overestimate the damping ratios of two-DOF systems in some cases.