Forced vibro-acoustical analysis for a theoretical model of a passenger compartment with a trunk—Part II: Experimental part

In this paper, experimental investigation is carried out to validate the simulation results obtained by a new analytical model and the plane wave theory analysis, which were proposed in Part I of this work. In preliminary studies, the relation between a neck and a natural frequency is reviewed from a practical point of view, by using a second-order polynomial, for a coupled structural-acoustic system with the double cavities connected by a neck. The natural frequency increases with the neck's cross-sectional area, but the increasing rate decreases with the increasing cross-sectional area. On the contrary, it decreases as the neck approaches the corner from the center, but the decreasing rate increases around the corner. In acoustic experiments, the frequency response functions of two simplified rectangular double-cavity models and a half-scaled car model made out of Plexiglas are measured and compared for different cross-sectional areas and positions of a neck connecting two cavities. Experimental results qualitatively agreed well with the simulation results of Part I. The cavity-controlled mode of the coupled structural-acoustic system is more strongly affected by acoustical modification, which means the change in the neck's position and cross-sectional area considered in this paper, than by structural modification.