The Location And Structure Optimization Of Hangers Of Commercial Vehicle Exhaust System

With the continuous development of vehicles manufacturing technology, higher demands of driving and riding comfort from auto consumers is appeared. Not only NVH performance of vehicles is related to customers’ driving and riding experiences, but also it’s a performance of research and developmental strength of vehicle manufacture companies. During daily driving, excite of vibration from road and engine is passed to the exhaust system, and then the vibration from exhaust system is transmitted to the vehicle body via hangers. Uncomfortable feelings from a steering wheel, seats and other parts to driver and passengers are caused by the vibration. Not only driving and riding experiences are bothered, but also life of vehicle parts. Therefore, Setting on a research about the NVH performance of exhaust systems is necessary.In this paper, the exhaust system of a commercial vehicle is treated as a research object. Aiming at the problem that remarkable vibration of the driver’s seat was realized during a test drive, a finite element analysis model of the exhaust system was established, and the key processes of model establishment were explained. Modal and frequency response analysis was conducted via FEM preprocessing software Hypermesh, solver MSC.Nastran and postprocessing software Hyperview. Location of hangers was optimized based on the method of Average Driving Degree of Freedom Displacement. The influence to first order modal frequency from size and overlap ways of hangers was investigated and the structure of hangers was optimized via Finite Element Analysis of the first order modal of some hangers. At last, took the actual location limits of chassis and frame into consideration, combined the ways to optimize location of hangers and methods to improve the first order modal of hangers, the velocity frequency response curves of driver’s seat mounting spots in different cases were studied, the best location and structure of hangers were obtained. The peak vibration velocities of driver’s seat mounting spot were decreased successful. The amplitude of decrease is about 20.17%. The peak velocities are in line with the designed demand.