多轴载荷下缺口件的疲劳寿命估算方法

提出了一种多轴载荷下缺口件的疲劳寿命估算方法。该方法基于临界平面理论,计算出缺口件各部位的多轴疲劳损伤参数,以损伤参数最大的部位为缺口件的多轴疲劳危险点。根据临界距离思想,提出了热点法和线法的临界距离的计算方法,采用热点法和线法考虑缺口件疲劳危险点附近损伤梯度的影响,以临界距离修正的损伤参数计算多轴载荷下缺口件的疲劳寿命。采用SAE1045钢缺口件的多轴疲劳试验对该文提出的寿命估算方法进行评估和验证,结果表明：该文所建立的寿命预测方法具有较好的预测能力,预测结果大部分分布在试验结果的3倍分散带之内。

ESTIMATION METHOD FOR FATIGUE LIFE OF NOTCHED SPECIMEN UNDER MULTI-AXIAL LOADING

An estimation method for the fatigue life of notched specimen under multi-axial loading is proposed. The multi-axial fatigue damage parameter in every part of notched specimen is calculated based on a critical plane criteria. The location of notched specimen with the maximum damage parameter is taken as a multi-axial fatigue dangerous point. The critical distance calculation methods of a hot point method and a line method are proposed based on a critical distance thought. The hot method and line method are taken to consider the effects of a damage gradient nearby the fatigue damage point of notched specimen. The modified damage parameter based on a critical distance is taken to calculate the multi-axial fatigue life of notched specimen. The method of estimation fatigue life is evaluated by the multi-axial fatigue tests of SAE1045 steel notched specimen. The result shows that the estimation method for fatigue life has good predictive ability. The prediction results are almost within a factor of three scatter bands of test results.