机械产品中绝大多数机器都是在交变应力下工作，而材料或机件在长期交变应力下出现裂纹，随后失效的现象称为疲劳断裂破坏。实际构件中不可避免地存在材料缺陷和应力集中，而在这些地方往往萌生出来表面裂纹或龟裂纹。因此就发展了一种新的设计思想——损伤容限设计。即允许机 The vast majority of machinery products are working under alternating stress, and materials or parts under long-term alternating stress cracks appear, then the failure phenomenon known as fatigue fracture failure. There are inevitably material defects and stress concentrations in the actual components, and surface cracks or crackles are often sprouted in these areas. Therefore, the development of a new design idea - damage tolerance design. That allows the machine