考虑温度影响的排气系统断裂原因仿真分析

Simulation Analysis of Fracture Cause of Exhaust System Considering High Temperature Effect

针对某汽车排气系统在使用中发生断裂故障的现象,采用有限元方法,考虑实际工况中温度的影响,对排气系统进行热模态与热疲劳性能仿真分析。得出在高温载荷作用下,排气系统的模态频率有所下降,某阶模态频率下降至发动机激励频率附近。排气系统在高温使用工况下的疲劳寿命大幅下降,且疲劳寿命最小处与实际断裂位置相同。得出了高温环境对排气系统疲劳性能有重要影响,而结构中存在的共振现象进一步加剧了排气系统的疲劳失效,确定了排气系统断裂故障产生的主要原因。

Aiming at the phenomenon of fracture fault in the use of an automobile exhaust system, a finite element method was used to simulate the thermal mode and thermal fatigue performance of the exhaust system, taking into account the influence of temperature in the actual working conditions. It is concluded that the modal frequency of the exhaust system decreases under the action of high temperature load, and a certain modal frequency drops to the vicinity of the engine excitation frequency, and the fatigue life of the exhaust system decreases greatly in the high temperature service condition, and the position with minimum fatigue life is the same as the actual fracture position. The conclusion is that the high temperature environment has an important influence on the fatigue performance of the exhaust system, and the resonance phenomenon in the structure further exacerbates the fatigue failure of the exhaust system, and the main causes of the fracture failure of the exhaust system are determined.