Simulation Analysis And Control On Body Structural NVH Performance Of A Pick-up

With the rapid development of the automotive industry, the noise and vibration performance of car is a very important indicator which measures car’s brand quality. The control of vehicle noise pollution by state and government becomes increasingly strict. The demand of drive and ride comfort by consumers becomes increasingly high. Both government and customer forces make automobile company pays more attention to improvement of vehicle noise and vibration performance, and take it as the highlight of a new car marketing. Therefore, researching on the noise and vibration performance of car actively has a very important meaning to promote brand competitiveness of automobile company and independent innovation capability.The research issue of this article derived from body structure NVH development projects of company’s new pick-up. According to actual engineering demand in the process of body structure NVH development on pick-up, taking target system of body structure NVH as a guide,this article carryed on a study of CAE simulation analysis and control to structure NVH performance of BIW and TB, using vibration mechanics and other disciplines theory, and modal analysis, body structure sensitivity analysis, acoustic plate contribution analysis and other engineering theory, as well as multi-objective optimization technology based Isight platform.Finally, various body structure NVH performances achieved the objective requirements successfully which was formulated originally, and interior structural noise and vibration of this pick-up was controlled effectively. The main research contents and results are as follows.1.BIW finite element analysis model was established, carrying on structural mode analysis,bending stiffness analysis, torsional stiffness analysis, and origin dynamic stiffness analysis of attaching points of BIW. The results showed that bending stiffness achieved the BIW-class objective requirement; Structural mode and torsional stiffness did not achieve the objective requirement, and they needed to carry on multi-objective optimization; origin dynamic stiffness of attaching points did not achieve the objective requirement. Finally, origin dynamic stiffness was controlled through improving the structure of attaching points.2. Multi-objective optimization analysis based Isight platform was carried on to structural mode performance, bending stiffness and torsional stiffness performance, and lightweightperformance of BIW. Firstly, the initial design variables were selected by parameters desigh of experiment and sensitivity analysis. Secondly, enough samples were collected by optimal latin hypercube desigh of experiment. After that, response surface approximation model which met the fitting accuracy requirements was established by least square method. Lastly, BIW multi-objective optimization analysis was carried on by archive micro-genetic algorithm. After optimization, structural vibration performances of BIW all achieved the objective requirements,and the total mass of BIW also declined.3.TB and acoustic cavity finite element analysis model were established, carrying on structural mode, acoustic cavity mode, VTF, and NTF analysis of TB. The results show that other performances all achieved the TB-class objective requirements except NTF, and NTF needed to be controlled by controlling structural vibration and acoustic radiation of the key body panels.4.3D random road model and vehicle multi-rigid-body dynamics model were established by Matlab and ADAMS/Car. Vehicle dynamics simulation analysis based FDE was carried on,obtaining road excitation spectrum in body and frame junction by extracting and fourier transforming. Simulation analysis and forecast was carried on to interior structure noise under the road excitation. The results show that interior structure noise performance did not achieve the objective requirement, and it needed to be controlled by controlling structural vibration and acoustic radiation of the key body panels. After that, plate acoustic contribution analysis based ATV was carried on, finding out body panels which contributed largely to the interior noise level.Finally, interior structure noise performance was controlled by improving the structure of key panels. Moreover, NTF performance of TB also achieved the objective requirement by analysis verification.