对某车用增压汽油机开发过程中出现的国产涡轮蜗壳开裂问题进行了研究，从材料、生产工艺和设计试验等方面综合分析开裂失效因素，建立蜗壳流固耦合解析模型，应用热机械疲劳分析方法进行设计优化。先用CFD方法计算得到蜗壳热交换边界，然后求解蜗壳在周期冷热循环中的瞬态温度场，将瞬态温度结果输入FEA模型分析后得到蜗壳在周期冷热循环中的瞬态应变变化。根据应变变化幅度推测热机械疲劳开裂风险，提出了可取代原进口A3K蜗壳的国产1.4837Nb蜗壳优化新方案，并通过了发动机冷热循环耐久试验。研究结果表明了所建方法对解决蜗壳开裂问题实用可行，能够满足工程要求。

The cracking problem of domestic turbine housing in the development process of vehicle turbocharged gasoline engine was studied. The cracking failure factors were comprehensively analyzed from the aspects of material, production process and test design. Then the fluidsolid coupling analytical model of turbine housing was established and further optimized with the thermalmechanical fatigue analysis method. The heat transfer boundary of turbine housing was calculated by CFD method, its transient temperature field in a periodic thermal cycle was then solved and its transient strain change in the cycle was finally acquired by inputting the calculated transient temperature result into FEA model. According to the variation of strain, the risk of thermalmechanical fatigue cracking could be estimated. The optimization scheme of replacing imported A3K turbine housing with domestic 1.4837Nb one was put forward and verified by the engine cold and heat cycle endurance test. The results show that the proposed method is feasible to solve the cracking problem and can meet the engineering requirements.