Transient contribution analysis of vibro-acoustic system based on mutual mean compliance

Abstract

In this paper, time domain mutual mean compliance is proposed to reduce transient vehicle interior noise caused by discontinuous impact force from road surface. The interior noise is caused by coupling of structural vibration and acoustic modes. Therefore it is difficult to find an efficient design to attain light weight and comfortable interior noise performance. In frequency domain noise and vibration problem, by applying frequency domain mutual mean compliance to vibro-acoustic system, it is possible to separate the sound pressure into the contributions of structural system, acoustic system and coupling effect between structural systems and acoustic systems. Moreover mutual mean compliance shows not only contribution but also sensitivity of structural system, acoustic system and coupling effect, coincidently. Consequently, most sensitive part for reducing sound pressure without weight increase can be detected. In this paper, to reduce transient interior noise, mutual mean compliance was applied to time domain problem. The time domain mutual mean compliance can be calculated by using inverse fourier transform, but its application is restricted to linear system. To overcome the restriction, this paper presents a formulation of time domain mutual mean compliance based on central difference method that is a one of the numerical integration method. And it is shown theoretically that contribution and sensitivity of structural components to the transient interior noise can be evaluated by using proposed time domain mutual mean compliance. As an application, time domain mutual mean compliance is applied to a simple automobile body model and countermeasure for transient interior noise that attain light weight also is detected.