ACCURACY OF MODAL APPROXIMATIONS FOR DYNAMIC RESPONSE ANALYSIS OF NON-PROPORTIONALLY DAMPED MECHANICAL STRUCTURES

摘要

Non-proportional damping does not allow the classical mode superposition for the determination of the dynamic response of structures, and necessitates more time consuming and complex computation techniques to be used. In order to avoid the expense of these solution techniques, different approximate methods have been proposed. The most popular of these is the uncoupled mode superposition method. The single mode method has recently been suggested as an alternative and tested for simple discrete systems. In this paper, the accuracy of single mode method when used for the dynamic response analysis of structures is investigated by analyzing clamped-clamped and clamped-free beams with varying amount and distribution of damping. The performance of single mode method is also compared with that of uncoupled mode superposition method. The exact values on which the accuracy check and comparison are based, are obtained by using complex mode superposition method.