S45C钢轴向-扭转两阶段载荷下的疲劳寿命预测

Fatigue Life Predictions of S45C Steel Under Push-Pull and Torsional Two Phase Loadings

针对S45C钢进行了一系列拉压载荷与扭转载荷不同加载顺序疲劳试验,用以考察载荷的改变对损伤和寿命的影响.试验结果表明,先拉压后扭转载荷下失效时的损伤值大于1,先扭转后拉压载荷下失效时的损伤值多数小于1,载荷模式和应力水平共同影响着失效时的损伤值.采用线性损伤律、双线性损伤律、损伤曲线方法和Morrow的非线性损伤律进行了寿命预测.从预测结果的比较看,各模型均具有过于安全的预测趋向.

A series of fatigue experiments were conducted on S45C steel under the push-pull and torsional (loadings) with two phases in order to reflect the effect of the loading sequence changing on damage and fatigue life. It can be seen that the damage summation is greater than 1 in the push-pull loading followed by torsion and less than 1 in the torsion followed by push-pull for the most experimental results. The loading mode and stress level have effects on the fatigue damage. The fatigue life predictions are obtained by the linear damage rule, double linear damage rule, damage curve approach and the plastic work model of Morrow. Then the results of (predictions) are compared. As a result, over-conservative predictions are presented by the models discussed.