Abstract
With the development of box structure like a car or train, noise reduction is required for such structures with cabin inside. Noise problem with structural vibration has been studied as coupled structural-acoustic system. In a previous research, we proposed an identification method for acoustic dominant coupled mode accompanied by resonance mode. It is considered to noise reduction by structural modification using a coupled mode characteristics. The purpose of this study is ”to carry out noise reduction for the acoustic dominant mode by the structural change ”. A method is proposed that modifies structural modal characteristics based on dynamic absorber mechanism. In the method, acoustic system is regarded as a main system and the structural system to be changed is regarded as an additional system. The proposed method is verified by FEM simulation. Results of numerical analysis are showing the sound pressure reduction effect. For validation of the practicality of the method, experiments using a car are carried out. The relationship between sound pressure reduction effect and excitation conditions to the structural system is verified. Through the experiments, it is shown that the noise reduction due to structural modification in the coupled system is possible. The necessary condition for applying the proposed method is also examined.
