Abstract: The vibration performance of Cross Car Beam (CCB) assembly is an important evaluation parameter in the NVH performance of complete vehicle.Modal parameters of constant-diameter bend cross car beam system were calculated via the finite element software Optistruct.The effects of tube thickness,tube diameter and front body bracket thickness etc on the CCB vibration performance are investigated by orthogonal test method based on finite element model.The results show that the tube thickness is the key structure parameters.The position of connection point between the front body bracket and body,front body bracket thickness and the thickness of H-type bracket also have a significant impact on the CCB vibration performance.According to the analysis results,select the thickness of three parts on the CCB as the design variables.Then mathematical model is established in Optistruct and the CCB structure is optimized,which obtains a better balance among the whole mass and natural frequency and stiffness,improving the natural vibration characteristics of cross car beam assembly.

Key words: cross car beam, modal analysis, orthogonal test, structure optimization