自動車用積層吸遮音材の遮音性能解析

Abstract

This report shows effect of sound insulation by adhesion of porous materials and film laminated panel. It deals a technique for estimating damped vibration of automotive body panels with sound-proof structures. It calculates damping properties for sound-proof structures involving elastic body, viscoelastic body and Biot type porous materials by three-dimensional finite element method. In this analysis, particle displacement vectors for internal air in the porous materials are adopted as unknowns for the discretized equations for finite element method. And displacement vectors for frame in the porous materials are also selected as the unknowns. A numerical code is developed. For numerical examples, Biot type porous materials are sandwiched between panel and film, and laminated film. Frequency response functions were calculated for panels laminated with porous material (felt) and viscoelastic body (film) and porous material (felt) using this technique, the calculation results almost agreed with the experimental results. And effect of the vibration performance by with/without adhesion is clarified. At with adhesion, the internal air and the frame in the porous material are same vibration. But at without adhesion, the internal air and the frame in the porous material are greatly different vibration. It is thought that change of sound insulation takes place by this.