Analysis And Research On NVH Performance Of A Car Body

The vehicle NVH performance directly affects the comfort of the car. It is one of the important evaluation indexes of the quality of vehicle. At the same time it is also one of the main factors influencing the competitiveness of the automobile market. And the car body as the most basic system of the whole car, which is very important to the performance of the vehicle NVH. In this paper, a car body as the research object, through the finite element method for the body structure of the static and dynamic characteristics of a comprehensive analysis and research, to find out the impact of the structure of the NVH performance of the body. Based on the analysis of the acoustic characteristics of the vehicle, the influence of the vehicle body structure on the interior noise is studied in this paper. Finally, through the optimization of the body design, improve the body NVH performance. The research work of this paper mainly includes:(1) The finite element model of car body is established by using HyperMesh software, the structural modal and static stiffness of the body are calculated, and finally the structure and performance of the vehicle are understood. Through the finite element analysis, it is concluded that the first order torsional frequency and bending stiffness of the vehicle body is lower than that of the same type, which affects the performance of the NVH, so it is necessary to optimize the structure of the vehicle body.(2) This paper analyzes the key methods on the body of the ground dotted the dynamic stiffness characteristics of frequency response. By analyzing the dynamic characteristics of these key points under external excitation, the frequency of dynamic stiffness is found, which provides the boundary conditions for the vehicle body noise transfer function analysis at the later stage.(3) This paper established the finite element model of the body and the acoustic solid coupling model. And the frequency response analysis of car body vibration velocity are used as boundary conditions, the transfer function between the input and output structure of body pressure calculation. Through the analysis of the contribution of the peak pressure at the point of reference, the paper analyzes the influence of the main panel parts of the body structure on the acoustic characteristics of the vehicle.(4)This paper introduces the process and method of multi objective optimization of vehicle body structure. Through Plackett Burman design selected 15 body components as design variables, and the Hamosilei experimental design methods to collect the design variables and the response of the sample values. According to the experimental results, the Kriging approximate model of the structure and performance of the vehicle body is established, and the multi objective genetic algorithm is used to calculate the Pareto front solution set. Finally, the accuracy of the optimization scheme is verified by simulation results.