缺口件疲劳寿命预测新方法

采用有限元方法针对缺口件多轴疲劳实验结果进行模拟。结果表明,相同路径条件下,随着缺口半径减小缺口根部附近的应力梯度显著增加。基于缺口根部应变值,采用等效应变法进行疲劳寿命预测,预测结果随缺口半径的减小而偏于保守。采用应力梯度法确定有效距离,相同路径下,随着缺口半径的减小有效距离减小;依据该有效距离处的等效应变进行疲劳寿命预测,总体预测结果较为分散且偏于不安全。基于实验及有限元模拟结果,提出了基于应变梯度的有效距离确定的新方法,大部分疲劳寿命预测结果位于2倍分散带内。

A New Method of Fatigue Life Prediction for Notched Specimen

The simulations of the notched specimens under multiaxial loading were conducted by finite element method.The simulation results show that the stress gradient increases with the decrease in notch radius for the same strain path.The equivalent strain method is used to predict the fatigue life based on the strain at the notched root.The prediction results are more conservative with the decrease in notch radius.The effective distance is determinated by the stress gradient method,and the effective distances are decreased with the decrease of notch radius for the same strain path.The fatigue life is predicted based on the strain at the effective distance,and the predictions are scattered and unconservative.Combining the test results and simulations,a new method determinating the effective distance is presented considering the strain gradient.Most prediction results are in a factor-2 scatter band.