Vibration Characteristics Analysis And Optimization Of A SUV Exhaust System

Exhaust system is an important part of the internal combustion engine,its work quality directly affects the car's vibration,noise and pollutant emissions.So,improving the NVH performance of the exhaust system plays an important role in improving the vehicle's NVH performance.However,due to the complex structure of the exhaust system,it is difficult to use the traditional vibration theory to study its performance.In this paper,a finite element model of the exhaust system is established by using Hypermesh software,and the finite element model of the exhaust system is calculated by Nastran software.The reliability of the finite element model of the exhaust system is verified bu comparing simulation modal results and experimental modal analysis results.The static response of the exhaust system can be used to understand the static load distribution of the exhaust system.The dynamic response of the exhaust system is investigated in the frequency response analysis,and the transmission force of the lifting lug is observed.The dynamic stiffness of the hook is analyzed before the vibration isolation of the exhaust system is analyzed,because the dynamic stiffness of the hook is an important factor affecting the vibration isolation rate,then the vibration isolation rate of the exhaust system is analyzed.Through the above calculation and analysis,the dynamic stiffness and the vibration isolation rate of the hook are basically satisfied,but the static displacement of the individual suspension points is not up to the standard,and the force transmitted to the vehicle body through the lifting lug is close to the dangerous value and needs to be optimized.(ADDOFD)is used to optimize the position of the hook of the exhaust system.Because of the limitation of the chassis space of the vehicle,only one of the hooks has been changed,and the static and dynamic characteristics of the exhaust system after changing the position of the hook are all have improved.The sensitivity analysis of some parts of the exhaust system optimized by the hook position is carried out.With the pipeline thickness,lug stiffness and bellows stiffness as the optimization parameters,the transmission power of the lifting system and the modal frequency of the exhaust system corresponding to the different parameters is obtained by orthogonal test.Processing the optimization of the results to get the best combination of exhaust system parameters.According to the results of the static analysis of the optimum combination parameter,the substandard results can satisfy the requirement.The analysis of the exhaust system vibration characteristics and optimization process of this article has a certain value of engineering,it can be effective for enterprises to develop exhaust system cycle and cost savings.