纯铜圆棒缺口试件拉压循环下的疲劳寿命分析*

对纯铜光滑试件和缺口试件的疲劳寿命规律差异进行探讨。通过光滑试件和缺口试件的循环疲劳试验和缺口试件的局部循环弹塑性应力应变响应分析,结合数值模拟与实验,比较了现有寿命预测方法对缺口试件寿命预测结果的差异。研究结果表明:传统的等应变幅等寿命的概念对于缺口试件的疲劳评估是不合理的;局部应力应变法用于大缺口试件的寿命预测结果可得到基本合理的结果;但对小缺口试件估测寿命结果不合理;应力梯度法对缺口试件寿命估测结果较局部应力应变法合理,因此可认为应力梯度是影响光滑和缺口试件疲劳寿命差异的重要因素。

Fatigue Life Analysis of Copper Notched Round Specimen under Tension - Compression Cyclic Loading

In this paper, the fatigue life differences of the copper smooth and notched round specimens were discussed. The response of the local cyclic elastic plastic strain and stress of the notched specimen was analyzed. The fatigue tests of smooth specimen and notched specimen were carried out. Then the fatigue life predictions with the existing life prediction method of notch samples were compared by numerical simulations and experimental tests. The research shows that: The traditional concept of the same strain amplitude leading to same life for notch samples may be not reasonable; it exists obvious deficiency when we use local stress-strain method for life prediction of notched specimen; whereas the stress gradient method is more reasonable for estimating the fatigue life of notched specimen; it is also found that the fatigue life prediction obvious batter when it made by the method considering stress gradient. So the conclusion is that the stress gradient near notch root has a great influence on the fatigue life of notched specimen.