孙晶晶1,2，马庆镇1,2，李连升1,2，王宝军1,2
1.内燃机可靠性国家重点实验室，山东潍坊261061;2.潍柴动力股份有限公司，山东潍坊261061
摘要：针对某6缸发动机高镍铸铁排气管在试验过程中出现的裂纹故障，基于流固耦合方法，利用有限元分析软件对故障排气管进行温度场、应力场和低周热疲劳计算分析。计算结果表明，排气管应力幅值较大区域和低周热疲劳计算寿命较低区域均与试验过程中发生的裂纹故障位置相吻合；冷热冲击工况下较大应力幅值产生的塑性应变是造成排气管热疲劳的主要原因。改进排气管结构，去掉靠近增压器法兰的加强筋，减薄增压器法兰，并对改进方案进行仿真分析和试验验证。结果表明，改进后排气管的低周疲劳寿命提高至3000次以上，改进方案有效，为后续排气管结构设计以及可靠性研究提供参考。
关键词：排气管；裂纹；流固耦合；低周疲劳
Abstract:Based on the fluidsolid coupling method, finite element analysis software is used to calculate and analyze the temperature field, stress field and low cycle thermal fatigue of the high nickel cast iron exhaust pipe of a sixcylinder engine. The calculation results show that the large area of the stress amplitude of the exhaust pipe and the low fatigue life area of the low cycle fatigue calculation are consistent with the crack fault location during the test；the larger plastic strain caused by larger stress amplitude is the main cause of exhaust pipe thermal fatigue under cold and hot shock condition. The exhaust pipe structure is improved by removed the stiffener near the supercharger flange and thinned the supercharger flange. The simulation analysis and test verification of the improvement scheme are carried out. The results show that the low cycle fatigue life of all parts of the improved exhaust pipe is increased to more than 3000 times, and the improvement scheme is effective, which provides a reference for the subsequent exhaust pipe structure design and reliability research.
Keywords: exhaust pipe; crack; fluidsolid coupling; low cycle fatigue
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