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对不同取向、带应力集中状态下镍基单晶合金构件的低周疲劳寿命进行了研究。在理论应力集中系数和载荷比确定的前提下,只要确定了缺口根部的剪应力范围,在不考虑分散性的情况下,缺口试棒的寿命是确定的。而此时,光滑试棒也一定存在某一个应力水平,在该应力水平下光滑试棒与缺口试棒的寿命相等;这时等寿命的光滑试棒与缺口试棒的最大剪应力范围之间存在一定的关系。根据这种关系,本文建立了剪应力范围的修正系数法,其与试验所得到的不同取向缺口试棒的低周疲劳寿命之间的最大偏差倍数为3.45,而直接采用光滑试棒剪应力范围寿命公式与实验寿命之间的最大偏差倍数为1681倍。结果表明,采用剪应力范围修正系数法预测不同取向的缺口试棒低周疲劳寿命具有较高的精度。
The low cycle fatigue life of nickel-base single crystal alloy under different stress and orientation was studied. Under the premise of determining the theoretical stress concentration factor and the load ratio, as long as the shear stress range at the notch root is determined, the life of the notched test rod is determined without considering the dispersibility. At this time, the smooth test bar must have a certain level of stress at this level of stress equal to the life of the smooth test bar and notched test bar; this time between the life of the smooth test bar and notched bar maximum shear stress range There is a certain relationship. According to this relationship, the correction coefficient method of shear stress range was established in this paper, which is 3.45 times of the maximum deviation from the low cycle fatigue life of different orientation notch test bars obtained from the test, and the direct shear stress range The maximum deviation between life formula and experimental life is 1681 times. The results show that the low-cycle fatigue life of notch test bars with different orientations is predicted by using the correction coefficient of shear stress range.