某乘用车催化器总成低周疲劳寿命预测

Low cycle fatigue life prediction of a catalytic converter assembly for passenger vehicle

鉴于目前SUS441铁素体不锈钢催化器总成应用低周疲劳寿命预测经验通用公式精度低的不足,对SUS441材料进行高温拉伸试验数据采集,拟合修正了Manson-Coffin公式疲劳寿命预测参数;通过STAR-CCM+软件和ABAQUS软件建立基于体映射法的流-固-热耦合模型,分析了催化器总成在4个工作循环后的热负荷,对SUS441催化器总成进行低周疲劳寿命估计。结果表明,温度场仿真结果与试验数据在误差范围内,模型可信度高;利用修正公式得到应变-低周疲劳寿命曲线,进行寿命预测,通过发动机台架冷热冲击耐久试验证明修正公式比经验通用公式更准确,该结果可为催化器总成设计开发提供指导。

In view of the low accuracy of the low cycle fatigue life prediction experience universal formula for catalytic converter assembly made of ferritic stainless steel SUS441,high temperature tensile test data of SUS441 material had been acquired,in order to fit the corrected Manson-Coffin formula of life prediction parameters.A fluid-solid-heat coupling model based on volume mapping method by STAR-CCM+software and ABAQUS software was established,the low cycle fatigue life of SUS441 catalytic converter assembly was predicted after four working cycles.The results show that the model has high reliability because the temperature field simulation and test data were within the error range.Using the corrected formula to obtain the strain-low cycle fatigue life curve for life prediction,the corrected formula is more accurate than experience universal formula through the engine bench thermal shock test,which provides an effective guiding role for the design and development of catalytic converter assembly.