Fatigue crack growth life is dominant in total life of components with notches or welded joints, which are unavoidable in most of structures and machines.

• 疲劳裂纹增长寿命决定了主要元件，包括凹口和焊接件的整个寿命，这些元件在绝大部分的结构和机器中是不可以避免的。