Fatigue Limit under Mean Stress
The fatigue limit under preload indicates how much dynamic load a component can still endure when it is already under static load. This is graphically represented in Haigh diagrams.
Physical-Chemical Mechanism of Action
The fatigue limit under preload describes the maximum dynamic vibration amplitude that a component can endure when it is already under a static load. This limit depends on the material structure and the type of loading.
Metallurgical Relevance & Risks in Welding
Incorrect preload or excessive dynamic load can lead to fatigue exhaustion, which over time results in cracks and failure of the component. This is especially critical in highly stressed components such as machine parts.
Workshop Practice & Action Instructions
When welding components under preload, the dynamic load on the weld must be controlled so that it stays within the fatigue limit. This requires careful planning and control of the stress. If necessary, special tools can be used to measure and regulate the dynamic load.