Complex modal analysis of the flexural vibration of a three-layered beam.

Abstract

This paper deals with the flexural vibration of the three-layered beam, the boundary condition of which is free-free. Three kinds of three-layered beams, core materials of which are all different and a normal steel beam, for reference, are tested. It was clarified that if the correct core material is chosen for the temperature, the vibration mode becomes a complex function and a high modal loss factor is achieved. Further, this paper presents the analysis method used to determine the damped normal mode (it is a complex function) described by Mead. The calculated modal loss factors have the same physical meaning as that in the one-degree of freedom. The accelerance at the driving point is calculated by the superposition of the obtained modes and values of the resonant frequency nearly equal to the result of the experiments are predicted.