NVH Performance Analysis And Structure Optimization Of A Passenger Car Body

With the continuous improvement of life quality and living standard,cars have been inseparable from people’s daily life.People pay more and more attention to the comfort of the car.The vibration and noise performance of the vehicle directly affects the ride comfort,which is one of the most important factors in the whole vehicle design process.The vibration noise of the vehicle body is the most important part of the vehicle vibration noise.How to quickly judge the source of the vibration noise,to find the components that produce the vibration noise accurately and to propose solutions to the problems has become the most concerned problem of the vehicle enterprises.This paper studies the vehicle body,the modal analysis,the vibration noise transfer function analysis and the structure optimization.The research methods of the key parts modal analysis,the position analysis of the exhaust system hook,the dynamic stiffness and the vibration noise analysis of the body are established,which can solve the noise problem of the body quickly and accurately.The main contents of this paper are as follows1.the research status of NVH optimization is analyzed and elaborated.The research ideas of analyzing key parts of the vehicle body by modal analysis method and the dynamic stiffness and vibration noise function of key joints of the vehicle body are determined.2.The principle and steps of the finite element analysis are described.Various connection modes in the analysis model are simulated by the finite element method.Finally,the finite element model of the body in white,exhaust system,door and instrument panel of the passenger car is established based on the real vehicle data.3.the modal simulation analysis of BIW,door,instrument panel and exhaust system is carried out by using modal analysis method.The modal modes of each component are analyzed.The results show that the modal modes of BIW,instrument panel and exhaust system are reasonable,and the vibration modes of door modes are easy to form resonance with the vehicle body.The rationality of the position of the hook of the exhaust system is verified by means of the displacement method of the average drive freedom,and the structural optimization of the door is carried out according to the modal mode.4.the dynamic stiffness analysis of key attachment points such as vehicle mounting and subframe is carried out by using IPI analysis.The dynamic response of each key attachment point under external excitation and the average dynamic stiffness value of each key attachment point are calculated.The dynamic stiffness of each attachment point meets the requirements.The vibration noise response value of the key attachment points in the vehicle is analyzed by using the noise transfer function and the vibration transfer function.The vibration noise response value of the response points in the vehicle is analyzed.The vibration noise response of some attachment points does not meet the requirements.5.the key attachment points which do not meet the requirements in the analysis of noise transfer function and vibration transfer function are analyzed by modal contribution analysis.According to the modal mode of the components corresponding to the peak mode,the structural optimization is carried out.The results are verified and analyzed by the vibration noise response function.All the attachment points meet the response target requirements.This paper analyzes and verifies the vehicle body and related parts by means of modal analysis,average drive freedom displacement method,noise transfer function,vibration transfer function,modal contribution analysis and structural optimization method.The NVH performance of the vehicle body is optimized separately,and the NVH performance of the vehicle body is improved significantly after optimization.In this paper,the analysis method can quickly determine the vibration and noise sources,and provide optimization ideas for the vibration and noise sources.