A Design Process using Body Panel Beads for Structure-Borne Noise

This paper presents a design process using beads on body panels to improve the structure borne noise of a passenger vehicle. Except reinforcements of structural members or applications of anti-vibration pads, it is difficult to find the effective countermeasures that can work for improvement of the structure-borne noise at the intermediate frequency range from 100 Hz to 300 Hz where the booming and low medium frequency noise occur. Thus the main goal is to make a systematic process and to find the effective countermeasures for this frequency range. The proposed process consists of 4 steps: a) problem definition, b) cause analysis, c) countermeasure development, and d) validation. Based on the general rule: ‘divide and conquer”, the complex problem can be simplified by performing a transfer path analysis at the first step and applying a panel contribution analysis at the second step,. The simplified problem is to improve the critical noise transfer function by modifying the beads on the concerned panel, the front floor. And then the problem can be conquered through a design optimization. The objective function is minimization of sound pressure in the concerned noise transfer function. The design variables are selected with the geometrical shapes of beads and patterns combining these beads on the front floor. Sensitivity analysis and optimization analysis are performed according to the process, which is defined in Taguchi's method. It is finally validated in the final step that the proposed design decreases the sound pressure of the concerned noise transfer function more than 5 dB, which meets the deployed design target.