Fatigue failure is a failure mechanism that results from the formation and growth of cracks under repeated cyclic stress loading, leading to fracture. It can result in failure at stress levels well below the material yield or ultimate strengths.
The video below discusses the mechanisms behind fracture, and how S-N curves can be used to predict the fatigue life of a component. It also discuss the effect of having a tensile mean stress, and how we can use techniques like the Rainflow counting method and Miner’s rule to consider complex cyclic stresses.