Systematic fea study of vehicle exhaust system hanger location using Addofd Method

Abstract

Under excitation of the engine and road surface, the vibration energy of the exhaust system which will result in the vibration of the body and produce the structure noise transfers to the body from the hanger. In view of these problems will cause noise, vibration and harshness (NVH) performance of the vehicle. A method called averaged driving DOF displacement (ADDOFD) is used to determine and optimize the exhaust hanger locations in this paper. Based on a sample vehicle, the Hyper Mesh and MSC. Nastrans oftware are adopted for meshing and calculation in the FEM modeling and vibration modal analysis of the exhaust system. Exhaust systems free-free mode and sum of its eigenvectors are offered using MSC. Nastran. Hanger locations are recommended at the position where the ADDOFD is relatively lower. Then static analysis and dynamic analysis of the exhaust system are done, and finally hanger locations of the exhaust system are selected. When the reasonable hanger positions have been decided, the vibration level of the body and the internal noise would have been decreased. This method can effectively select better NVH performance hanger locations in the earlier vehicle development process and can be extended to other types of vehicle, thus is instructive for saving both the time and the cost of operation.