Weight Reduction of Damping Materials on Vehicle Body Panels by using an Optimization with Sound Pressure Constraints 2012-01-0220

This paper presents an optimization method of damping material attached on vehicle body panels incorporated with trimmed body calculation up to 400 Hz. Damping sheets are modeled by using shell elements whose neutral plane are located away from the middle plane of the elements. In this method the offset value must agree with the average of the thicknesses of a panel and a damping sheet attached on it. Therefore, we implement the function that can automatically change the offset values according to the change of the thicknesses of damping sheets during the iterative calculations of optimization. Interior sound pressure levels are employed as the constraint conditions by utilizing the precise acoustic cavity models that have been recently developed. The developed optimization technique is applied to reduce the weight of the damping sheets on the floor panels of a sedan car. The levels of noise transfer functions that are proved to have high contributions to the performance of road noise are constrained in several one-third octave bands. The optimization calculation finds a solution that can achieve 1.5 kg weight reduction after several iterations. Moreover, the vehicle realized the optimal configuration proves to attain the almost the same road noise level as one with the original configuration