Modal Analysis And Optimization Of Vibration Of The Vehicle Exhaust System

The vibration of vehicle exhaust system is a key factor of vehicle NVH, and it plays an important role in the fatigue life of the exhaust components. When the engine works, it generates vibration greatly. And the vibration will be transferred to the exhaust system. The exhaust system is composed of different elastic hangers and rigid connectors, so it is a multi-DOF vibration system, so it is very difficult to research it by using some traditional method. Therefore, it is necessary to find an effective method to analyze and control the vibration of the exhaust system in the process of the optimum design.Since the exhaust system is a complicated vibration system, Lanczos method in ANSYS (an FEA software) is used in this paper to analyse the modal of the system in both free and restricted status, and get the natural frequency and the amplitude of every modal. Then, learn the actual natural frequencies and corresponding amplitudes of the system in those status, and compare them with the theoretical calculated results by using MAC method. The verification shows that the model can describe the actual system very well. However, because of the simplification of the model, this method is still not that accurate. Finally, use the optimization method to describe the process of the system optimization, and anaylse the sensitivity of the key components in the system, which lower the difficulties of designing the exhaust system.