船用天然气发动机废气旁通波纹管开裂故障失效分析

Cracking Failure Analysis of the Exhaust Bypass Bellows on Marine Gas Engines

针对某型船用天然气发动机300 h耐久试验中,废气旁通阀后波纹管多次发生开裂失效故障,对波纹管部件进行材料理化分析,补偿量设计校核和应力仿真计算以分析失效原因。结果表明:波纹管装配偏差、热膨胀超过补偿范围以及长期运行振动导致波峰和波谷等薄弱处应力超过许用应力,产生微裂纹,进而导致疲劳开裂。据此提出了相应的改进措施。

The bellows of a gas marine engine behind the exhaust bypass valve cracked many times during the endurance test of 300 h.In order to find out the cracking causes,physical and chemical analysis of materials,compensate value inspection,and simulation calculation of stress were carried out.The results showed that excessive stress at crest and trough caused by assembly deviation,thermal expansion exceeding the upper limit,and long-term vibration may lead to small flaws and then result in fatigue cracking.Improvement methods are offered based on the research.