A Brief Review on Fatigue

Fatigue is caused by repeated application of stress to the metal. It is the failure of a material by fracture when subjected to a cyclic stress. A significant feature of fatigue is that the load is not large enough to cause immediate failure. Instead, failure occurs after a certain number of load fluctuations have been experienced, i.e., after the accumulated damage has reached a critical level. Fatigue cracks usually start from the surface of a component, where fatigue damage begins as shear cracks on crystallographic slip planes. The surface shows the slip planes as intrusions and extrusions.