Vibration Characteristic Analysis and Structural Optimization of Automotive Exhaust System based on Finite Element Method

The vibration energy of an automotive exhaust system is transmitted to the chassis and body structure through hangers and suspension components, directly affecting the noise, vibration, and harshness (NVH) performance of the vehicle. This paper conducts a dynamic characteristic analysis of the exhaust system based on the finite element method, with emphasis on the numerical evaluation of the first-order mode of the hanger and its dynamic stiffness characteristics under constrained and free modal conditions. According to enterprise standards, the performance of the exhaust system hanger for a certain vehicle model is evaluated. The results show that the modal frequency of hanger 4 at 302.7 Hz barely meets the preset threshold of not less than 300 Hz. A structural improvement is then implemented for hanger 4 by increasing the exhaust pipe wall thickness from 1.2 mm to 1.5 mm, and the mechanical performance of the optimized model is further assessed through static analysis.After optimization, the modal frequency of hanger 4 is significantly increased to 354 Hz for the first-order free mode, and the dynamic stiffness curve remains below the threshold of 500 N/mm within the target frequency band from 50 to 200 Hz. Under the 1G condition, the support reaction force of 46.895 N and displacement of 3.895 mm, as well as the weld stress of 40.903 MPa under the 4G condition, all meet the strength requirements. The study verifies that structural optimization effectively improves the NVH performance of the exhaust system and provides a practical solution for addressing hanger failure in engineering applications.