黄政^1,2，李云涛¹，蓝军¹，俞小莉²，杨万里¹，王瑞平¹

1.宁波吉利罗佑发动机零部件有限公司，浙江 宁波  315336；2.浙江大学工程师学院，浙江 杭州  310058

摘要：为解决发动机在耐久试验过程出现的排气系统热端支架开裂故障，采用流-固耦合与低周疲劳分析相结合的方法分析故障原因，确定在冷热交替情况下，增压器涡壳反复热膨胀及收缩，不断拉拽和挤压增压器支架，形成热应变集中并不断累积，达到低周疲劳寿命极限，出现开裂。对支架进行优化，减小支架在开裂处温度梯度及刚度梯度并使其均匀过渡。优化后支架对应原开裂处的等效塑性应变降低到0.1%，消除热应变，并通过耐久试验验证。

关键词：热端支架；开裂；低周疲劳；塑性应变

Abstract：In order to solve the cracking fault of the hot end support of the exhaust system during the durability development of a engine, the method of combining fluid-structure coupling and low cycle fatigue analysis is used. It is found that under the condition of alternating cold and heat, the turbocharger volute expands and contracts repeatedly, and constantly pulls and squeezes the supercharger support. Thus the thermal strain is concentrated and accumulated until it reaches the low cycle fatigue life limit and cracks appear. The optimization is carried out to reduce the temperature gradient and uniform stiffness transition of the support at the crack. After optimization, the equivalent plastic strain of the support corresponding to the original crack is reduced to 0.001, the thermal strain is eliminated, and finally verified by the durability test.

Keywords:hot end bracket; crack; low cycle fatigue; plastic strain