Research Of Dynamic Characteristics For Passenger Car Exhaust System

With the fast development of our national economy,the Automobile Industry has become one of the most important pillars in economies.As an important index in NVH evaluation,the vibration and noise is paid more attention by factories.Because the vibration which produced by the working engine may deliver to the exhaust system.And the structure of the system is complicated and multi degree of freedom.It can't satisfied the requirement of modern design and car manufacturing if we only considerate the static characteristics of the exhaust system.Now more and more scholars do many studies and evaluations on the dynamic characteristics.Firstly,according to real data of the exhaust system to establish simplified reasonable 3D model through the CATIA software,save it as a kind of format,which ANSYS Workbench can recognize.After a reasonable meshing process,the finite element model of the exhaust system is generated.Then free and constraint boundary modal analysis between 0 to 200 Hz was preceded on the finite element model of the exhaust system and to get the frequency and vibration chart of different stage.Then the free modal of exhaust system is analyzed by the method of experimental modal analysis.It shows that differences between the frequencies in the first six stages are very small and the mode of vibration is almost the same.And engine speed which may make resonance in the passenger car exhaust system can be calculated.The working condition of idle speed and slow speed under neutral conditions home vibration test for passenger car exhaust system is also analyzed.Exhaust system completely avoids the engine idle main excitation frequency.So this can be thought that passenger car exhaust system design is reasonable.This method of using the finite element modal analysis and experiment modal analysis to research the vibration characteristics of exhaust system can be applied to evaluate the dynamic characteristics of vehicle exhaust system.It can improve the working performance and service life of the exhaust system,and improve the comfort of passenger cars.