多轴变幅加载下疲劳裂纹扩展速度的研究

Study on Multiaxial Cyclic Stress of Varying Amplitude Fatigue Crack Growth Rate

为了揭示出在多轴变幅加载下疲劳裂纹扩展速度的规律,利用了临界平面概念,把多轴载荷等效为单轴载荷,在考虑变幅加载的特征下,逐级利用恒幅疲劳裂纹扩展的速度公式,计算裂纹的总增加量,导出了等效载荷谱块作用下的疲劳裂纹扩展速度公式。通过对典型试件的疲劳寿命预测,验证了该公式的正确性。

In order to reveal the rule of fatigue crack growth rate by multi-axial cyclic stress of varying amplitude, based on a critical plane approach, equating the multi-axial loading with uni-axial one, with the characteristic of the cyclic stress of varying amplitude, adopting the formula of the fixed stress amplitude fatigue crack growth rate in different amplitudes, totaling up the incremental crack length, the fatigue crack growth rate formula is given under ranking methods equivalent cyclic stress of varying amplitude. By predicting the fatigue life of typical sample, the rule is verified.