Determination Method of an Excitation Force Point for Reducing Structure-Borne Transmitted Power on Flexible Plates Based on Structural Intensity

Abstract

The structure-borne sound in bending waves has been studied by many researchers. However, the majority of those studies have aimed at achievement of only measurement or calculation of structure-borne power. This paper presents a new determination method of an excitation force point for noise reduction. The method is based on modal expansions of structural intensity for controlling vibration energy flow. The modal expansions are expressed as the superposition of modal terms determined by the product of the weight coefficients and the product of two spatial derivatives of natural mode shapes, which is referred to as the "cross-modal functions". The weight coefficients depend on the excitation condition, and the cross-modal functions only depend on mode shapes. Therefore, if excitation point would be changed, we can control weight coefficients. Increasing a weight coefficient means to excite strongly the cross-modal function corresponded to the coefficient. As a result, the distribution of structural intensity can be modified. In this paper, we propose the method for determining excitation location which excites a non power transmission typed cross-modal function, which have no power transmission and relate to low noise. The numerical application results present a validity of the method.