高镍铸铁排气歧管低周热疲劳研究

摘要

针对某新开发的车用高镍铸铁排气歧管进行了低周热疲劳寿命预测研究，为获取准确的热边界条件，采用STAR-CCM＋与有限元软件进行基于疲劳寿命试验条件的非稳态耦合传热分析，得到了排气歧管的对流换热系数和温度场，建立了具有真实装配关系并施加螺栓预紧力的排气歧管有限元模型，在对等效塑性应变分析的基础上，结合Coffin-Manson公式进行寿命预测。结果表明，在排气歧管开发过程中，采用该方法可以快速对其热疲劳寿命进行评估。%The low cycle thermal fatigue life of a newly developed high nickel cast iron exhaust manifold for vehicle was pre -dicted.In order to obtain a more accurate thermal boundary condition , STAR-CCM+and FE software were applied to analyze non-steady coupled heat transfer based on fatigue life experiment .The convective heat transfer coefficient and temperature field of exhaust manifold were then obtained .The FE model of the exhaust manifold was established with accurate assembly relation a-mong different components and bolt pre -tightening loads .At last, using Coffin-Manson equation , life prediction was completed based on analysis of equivalent plastic strain .The result indicates that the analysis method could speed up thermal fatigue life prediction of an exhaust manifold during developing process .