基于焊缝品质参数区间模型的疲劳寿命预测方法

摘要

疲劳寿命预测中,焊缝品质参数如材料弹性模量E、疲劳强度系数σ:和指数b、疲劳延性系数ε'f和指数c往往存在不确定性.运用随机-遗传算法对焊缝品质参数进行区间估计,并结合Manson-Coffin公式构建上述不确定因素的区间模型,提出了一种疲劳寿命区间预测方法.首先,在双轴疲劳试验机上进行了基于应变控制的焊接试件疲劳寿命试验.其次,针对疲劳寿命试验数据,运用随机-遗传算法构建了焊缝品质参数区间求解模型,并结合Manson-Coffin公式建立了疲劳寿命区间预测模型.最后通过模型预测数据与试验数据对比证实了预测模型的精确性以及考虑焊缝品质参数不确定性的合理性.%Weld quality parameter—elastic modulus E,fatigue strength coefficient σ'f and exponent b,fatigue ductility coefficient ε'f and exponent c were always of uncertainty in fatigue life prediction.A method of fatigue life prediction was proposed by interval model which combined random-GA method with Manson-Coffin formula.Firstly,the fatigue life tests of welding specimen were carried out on biaxial fatigue testing machines based on strain control.Then,for fatigue life test data,fatigue life in terval prediction method was constructed by combining weld quality parameter interval solving model which was constructed by random-GA method with Manson-Coffin formula.Finally,the accuracy of this method and the rationality of considering the uncertainty of weld quality parameters were verified by the comparisons between the interval model predictive data and fatigue life test data.