某汽车排气系统支架应力分析及改进
张鹏1,王哲2,李俊芳1,徐文进1
1.克康(上海)排气控制系统有限公司,上海 200123;
2.上海交通大学机械与动力工程学院,上海 200240
摘要:为解决某汽车排气系统支架的开裂失效故障,通过断口电镜扫描分析、焊接质量检测、晶度分析等方法,确定支架失效原因为发动机振动引起的高周疲劳失效。设计加宽支架的2个支角并做圆角过渡和将支架的2个支角连成一体2种支架优化方案。对2种优化方案进行有限元振动激励响应分析,根据分析结果选择较优方案进行台架整体耐久振动试验验证。仿真结果表明:优化方案二支架的应力显著降低,在最大共振频率为193 Hz时的应力为48.4 MPa,较原支架应力降低了11.9 MPa;台架试验结果表明,优化方案二支架在2倍寿命循环后无明显损伤,满足耐久性考核目标。
关键词:排气系统;支架结构失效;高周疲劳;应力
Stress analysis and improvement of an exhaust system bracket
ZHANG Peng1, WANG Zhe2, LI Junfang1, XU Wenjin1
1. KATCON(Shanghai) Emission Control System Co., Ltd., Shanghai 200123, China;
2. School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Abstract:In order to solve the cracking failure of the automotive exhaust system bracket, the high cycle failure cause of the bracket is investigated by engine vibration through fracture scanning electron microscope analysis, welding quality inspection, crystallinity analysis and other methods. The two support angles of the widened bracket with rounded transition are designed, and connected the two support angles of the bracket into one. Two optimization schemes for the bracket are proposed. Finite element vibration excitation corresponding analysis is performed on two optimization schemes, and experimental verification based on the analysis results is also carried out. The simulation results show that the stress of optimization scheme 2 is significantly reduced, with a stress of 48.4 MPa at a maximum resonance frequency of 193 Hz, which is 11.9 MPa lower than the original support stress. The bench vibration durability test shows that the optimized scheme has no significant damage after 2 times the life cycle, meeting the durability assessment goal.
Keywords:exhaust system;bracket system failure;high cycle fatigue;stress