Calculation and analysis for acoustic radiation mode of strong and weak plate-cavity coupling system

A numerical method is proposed for analyzing the Acoustic Radiation Modes (ARM) of a plate-cavity coupled system based on the energy principle. In present method, the relationship between the sound pressure mode amplitude and the structural mode amplitude is constructed through the dynamic equations and the ARM is obtained by expressing the acoustic potential energy as a quadratic form of the structural mode amplitude. Compared to the previous theory, the present approach makes up the shortcomings in case of the acoustic cavity is an impedance wall or the structure-acoustic strong coupling. The accuracy and precision of present method are validated through numerical examples. Then the effects of wall damping and structure-acoustic coupling conditions on the characteristics of ARM are investigated. The numerical results show that the ARM radiation efficiency curve will peak at the acoustic mode frequencies. The peak value can be effectively suppressed by introducing impedance-walled boundary conditions, and the more pronounced the amplitude decay with the impedance value decreases. Specifically, the amplitude of the acoustic potential energy at the peak frequency of ARM radiation efficiency curve will decrease; Under strong coupling conditions, the acoustic potential energy response in low frequency is mainly motivated by the structural mode, and the response peak density is higher, and the amplitude is lower. The ARM radiation efficiency peak number is less, and the peak frequency is higher in the same bandwidth low frequency.