Firstly, we will look at the most common testing method – tensile testing. In the tensile test, a test piece is extended, usually to fracture, with a gradually increasing uniaxial tensile load, to determine the resistance of the material to the force.
Many applications exist where a material is subjected to a repeated cyclic stress. These materials are found to fail after a large number of applications of the stress even though the cyclic stress that is applied is below their yield strength.