This paper analyzes the mechanism of vibrational energy propagation and panel vibration generation at the point joints between frame and panel which can be applied to reduce the vehicle interior noise. In this study, we focused on the traveling wave in the early stage of propagation before the mode is formed and investigated the mechanism of panel vibration generation due to wave energy propagation and its reduction method.
First, we show theoretically that the out-of-plane component of the transmitted power at the point joint between frame and panel that contributes to panel vibration is associated with frame deformation. Then, we show through numerical verification that panel vibration can be reduced by reducing the transmitted power of the out-of-plane component and explain the effectiveness of the frame-to-panel joint design guidelines based on energy propagation analysis.
Next, this analysis method was applied to the vehicle body FEM model. Assuming road noise, an energy propagation analysis was conducted to reduce panel vibration when the suspension connection point was excited. The instantaneous structural intensity analysis was used to visualize the traveling wave flow to identify the sound panel, and the point joints that contribute to the ERP of that panel section were further identified by calculating the transmitted power of the out-of-plane component. Then, a simple structural modification intended to reduce this transmitted power was made at the point joints, and the panel ERP and interior noise were reduced. In conclusion, this study demonstrates the effectiveness of energy propagation analysis in clarifying the mechanism of vehicle interior noise.