应力控制下的Q345钢疲劳寿命预测研究

Study on fatigue life prediction of Q345 steel under stress control

基于Gerber模型和Goodman模型这两个考虑平均应力对疲劳寿命的影响的经典模型,提出了一个修正的疲劳寿命预测模型。在室温下,选取3个应力比R=-1、-0.75和-0.5,每个应力比下选取5个最大应力,对Q345钢进行单轴拉压疲劳实验。运用Gerber模型、Goodman模型和修正模型对Q345钢在不同应力比和最大应力组合工况下的疲劳寿命进行预测,并与试验结果进行比较分析。结果表明：修正模型预测寿命和试验寿命的相对误差绝对值平均值、相对误差绝对值最大值、标准差都较明显的小于Gerber模型、Goodman模型。修正模型比Gerber模型和Goodman模型更适合于Q345钢在不同应力比和最大应力组合工况下疲劳寿命的预测。

Based on the two classical models,namely Gerber model and Goodman model,which considering the effect of mean stress on fatigue life,a modified fatigue life prediction model was proposed. At room temperature,three stress ratios R =-1,-0. 75,-0. 5 and five maximum stresses under each stress ratio were selected to conduct uniaxial tension and compression fatigue test of Q345 steel. The Q345 steel fatigue life under different stress ratio and maximum stress combinations was predicted by using Gerber model,Goodman model and modified model,and were compared with the experimental results. The results show that the maximum value and the average value of absolute value of relative error,the standard deviation between the predicted fatigue life and the experimental fatigue life from the modified model are obviously lower than that from the other two models,which means that the modified model is more suit to predict Q345 steel fatigue life under different stress ratios and maximum stress combinations than Gerber model and Goodman model.