表面裂纹疲劳扩展的一种损伤力学方法

Continuum damage mechanics method for fatigue growth of surface cracks

以核反应堆中压力容器和管道的破前漏（ＬＢＢ）分析为背景，从连续损伤力学的角度研究了压力容器和管道中环向和轴向半椭圆表面裂纹在循环载荷作用下的疲劳扩展问题。以标量损伤因子表征材料的疲劳损伤，由裂纹尖端的损伤演化导出了与Ｐａｒｉｓ公式形式相似的裂纹扩展方程，给出了Ｐａｒｉｓ公式的物理意义。由此发展了一种分析表面裂纹疲劳扩展过程中形状演化问题的损伤力学方法。

With the background of leak before break(LBB) analysis of pressurized vessels and pipes in nuclear plants, the fatigue growth problem of either circumferential or longitudinal semi elliptical surface cracks subjected to cyclic loading is studied by using a continuum damage mechanics method. The fatigue damage is described by a scalar damage variable. From the damage evolution equation at the crack tip, a crack growth equation similar to famous Paris' formula is derived, which shows the physical meaning of Paris' formula. Thereby, a continuum damage mechanics approach is developed to analyze the configuration evolution of surface cracks during fatigue growth.