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Fatigue in Material

 This phenomenon leads to fracture under repeated or fluctuating stress. Fatigue fractures are progressive beginning as minute cracks and grow under the action of fluctuating stress. The fatigue properties of a material determine its behavior. when subjected to thousands or even millions of cyclic load applications in which the maximum stress developed in each cycle is well within the elastic range of the material. Under these conditions failure may occur after a certain number of load applications , or the material may continue to give service indefinitely. In many instances a component is designed to give a certain length of service under a specified loading cycle. Many components of high speed aero and turbine engines are of this type. 








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