As per the Science of Material Testing, Fatigue means the weakening of a material which is caused due to repeated applied force. It is a progressive structural damage that occurs when a material is provided for a continuous cyclic load. The nominal stress value which causes such type of damage may be less than the strength of the material which is generally known as the yield stress limit or tensile stress limit. The Fatigue stress in a material occurs when it is subjected to repeated cycle of loading and unloading.
Objectives of Performing Fatigue Test
The fatigue test is performed to understand the behavior of a material when subjected to repeated forces or load of the same magnitude but in a different direction. The test is performed to measure the life of a material. The test is used to measure the fatigue strength and crack resistance of the material which is commonly required to measure the quality of the material.
Types of Fatigue Test
Fatigue test can be performed mainly in two forms i.e. load controlled high cycle fatigue tests and strain controlled low cycle fatigue.