1. Stress fatigue method is a method to study the fatigue life and fatigue failure of materials by applying different stress loads. In the experiment, the material sample is placed under stress load, and the fatigue load under actual use conditions is simulated through the cyclic process of continuous loading and unloading. According to different stress amplitudes and loading times, the fatigue life curves of materials can be obtained.

2. Strain fatigue method is a method to study the fatigue life and fatigue failure of materials by applying different strain loads. Compared with stress fatigue method, strain fatigue method is closer to the stress state of materials under actual use conditions. In the experiment, the fatigue loading of materials is simulated by applying different strain amplitude and loading time.