Influence of different types of support on experimentally determined damping values

Identifying the source of any discrepancies between a numerical model and experimental data can be a time consuming and costly undertaking. Individual input parameters of a numerical model can only be determined experimentally. Out of the input parameters usually required for computer-aided structural dynamical models, damping is one of the most challenging ones to obtain. It cannot be measured directly and has to be derived from other measured values in the post-processing. Obtained damping value can be sensitive to the method utilized during the post-processing [1, 2]. Furthermore, boundary conditions which are common in numerical models like ideally free-free or fixed support, can be merely approximated in an experimental setup [3]. As a consequence, the influence of a chosen type of support on the damping of the test specimen cannot be neglected. In this study, the influence of different types of support on the obtained damping values are investigated. For this purpose, the structural dynamical behaviour of several test specimens, each being under several boundary conditions is measured with a laser scanning vibrometer. Each specimen under each boundary condition has been performed out several times in order to identify the reliability and reproducibility of the measurement. From the insights gained in the course of these investigations, suggestions are proposed for the reduction of the measurement effort in damping measurements.