NVH Performance Analysis And Structural Optimization Design Of Vehicle Body

With the improvement of requirement for vehicle comfort, improving NVH characteristics of vehicle is the principal means to upgrade the vehicle and improve the competitiveness. Based on a SUV, the finite element model of car body,acoustic cavity and acoustical-structure interaction has been built. The characteristic of NVH has been analyzed, including BIW(body-in-white modal), vehicle modal, acoustic cavity modal, the torsion and bedding stiffness of BIW, acoustical-structure interaction NTF, acoustical-structure interaction VTF and acoustical-structure interaction IPI. Using the volume and one order torsion and bend frequency as the objective function and constraints, the optimization of improving the body frequency has been done by using response surface method and optistruct. The results as follow:①The finite element models of car body, car and acoustic cavity have been built, the modal of car body, car and acoustic cavity has been analyzed. With the analysis one order torsion and bend frequency are get as 33.4Hz and 44.3Hz, which is the basis of the optimization of car body.②Based on the actual driving situation of car boy, the torsion and bedding stiffness have been analyzed. Compared to the car boy stiffness of the car, the result is reasonable. The curves of torsion stiffness and bedding stiffness have been gotten. Which indicates the stiffness of car body is uniformly distributed.③The finite element model of acoustical-structure interaction has been built by DIFF. the characteristic of NTF、VTF and IPI have been analyzed, with different stimulations the peaks of sound pressure, vibration and dynamic stiffness have been get, which indicate the characteristic of NVH is reasonable.④The experimental matrix has been get by Latin hypercube design, and the response surface models of car volume, one order torsion stiffness and one order bedding stiffness have been built by using response surface method. The optimization of genetic algorithm is used to optimize the thickness of plate, the result shows the quality has decrease 22.8kg, the torsion stiffness has increased2 Hz and the bedding stiffness has increased1.5Hz.