Structural optimization and verification of an automobile exhaust pipe

SUN Ying; LI Wu; QIN Zhen

doi:10.19471/j.cnki.1673-6397.2025.06.012

Abstract：To prevent resonance between the natural frequency of an automobile exhaust pipe,the main order vibration frequency of the engine,and the natural frequency of the cab acoustic cavity,the finite element model of the exhaust pipe is established by using Abaqus software,modal simulation analysis is carried out,optimization schemes are proposed,and comparative verification is conducted through modal analysis tests.The results show that the first-order natural frequency of the exhaust pipe is 24.23 Hz,while the engine idle vibration frequency is 25.00 Hz.The two frequencies are close to each other,indicating a high resonance risk.By adopting the two optimization schemes of changing the hanger position and adding an elbow to the straight pipe section of the exhaust pipe and conducting simulation analysis,the 11th-order natural frequency of the scheme that only changes the hanger position is close to the natural frequency of the cab acoustic cavity,which also has resonance risk.It is found that the first-order natural frequency of the exhaust pipe with an elbow added to the straight pipe section reaches 19.40 Hz,which effectively avoids the engine idle vibration frequency and solves the resonance problem between the natural frequency of the exhaust pipe and the engine idle vibration frequency.A comparison between the exhaust pipe modal analysis test and the finite element simulation shows that their vibration modes are basically consistent,and the deviations of the first-order and second-order vibration frequencies are both less than 8％,which verifies the effectiveness of the simulation model.