Fatigue
lastmod 2019-11-22created 2019-11-222 edits
Fatigue is when a material such as metal is repeatedly subjected to stress lower than its yield strength. Failure of a material due to fatigue is called fatigue failure. The larger the range of stress fluctuation, the fewer cycles it takes for failure to occur. The stress range at which the range of stress a structure can withstand takes a constant value regardless of the number of load cycles is called the fatigue limit.
Bending a wire back and forth repeatedly makes it snap, a typical example of fatigue fracture. When force is applied repeatedly to the same spot, fatigue accumulates inside, cracks form, and at some point the material fails. Materials and designs used in parts of structures, components, and the like where force is applied repeatedly due to vibration and similar causes must be resistant to fatigue fracture.