某车型排气系统焊缝开裂问题分析及优化

Fracture analysis and optimization of vehicle exhaust system

针对某车型的排气管与法兰盘间的焊缝在进行整车耐久路试期间发生开裂,通过焊缝切片实验、焊缝疲劳测试排除了焊缝开裂并非焊接工艺所致。运用有限元分析并经过模态测试对排气系统进行分析,确认排气管与法兰盘的焊缝开裂是由于波纹管动刚度在排气系统45.1 Hz和66.7 Hz的模态下出现峰值,引起焊缝应力集中所致。优化波纹管动刚度后,排气系统顺利完成整车路试耐久试验。结果表明:优化后的波纹管可有效避免焊缝出现应力集中,提高了排气系统的可靠性,满足整车耐久性能要求。

Aiming at the problem of fatigue fracture at the welding between exhaust pipe and flange during road test for vehicle durability,we carried out welding section experiment and welding fatigue test,and ruled out the possibility of welding procedure defect.Then finite element analysis and modal testing were used to analyze the exhaust system,confirming that the welding fracture was caused by the peak dynamic stiffness of the corrugated tube under the mode of 45.1 Hz and 66.7 Hz and the subsequent stress concentration to the welding.After optimizing the dynamic stiffness of the corrugated tube,the exhaust system went through the vehicle road test successfully.It was concluded that the reliability of the exhaust system was improved,meeting the durable performance requirements of vehicle.