Identification of dominant characteristics in the coupled structural-acoustic system using a transmissibility

Abstract

With the development of box structure like a car or plane, noise reduction technology is required. For interior noise reduction, it is necessary to identify a resonance mode which is affected by the acoustic characteristics. Meanwhile, noise problem with structural vibration has been studied as coupled structural-acoustic system. In case of coupled system, it is useful to understand a resonance mode as an acoustic dominant coupled mode for noise reduction. Hence, it is necessary to develop a method to identify the acoustic dominant coupled mode. The purpose of this study is ”identifying the acoustic dominant coupled mode by proposing the coupled structural-acoustic transmissibility”. The dominant characteristics of system in the coupled system and the coupled transmissibility are mentioned in a theory section. The proposed theory is verified by FEM simulation. It is possible to classify the dominant characteristics by analysing single system using the coupled transmissibility. For verifying the practicality of the method, experiments using a car are carried out. The coupled modes are identified by modal property identification experiment. Two coupled modes having an acoustic longitudinal 1st mode shape are identified. The acoustic dominant coupled mode is identified by measuring the coupled transmissibility. Hence, it is concluded that the acoustic dominant coupled mode can be identified by the coupled transmissibility.