The definition of fatigue testing can be thought of as simply applying cyclic loading to your test specimen to understand how it will perform under similar conditions in actual use. The load application can either be a repeated application of a fixed load or simulation of in-service loads. The load application may be repeated millions of times and up to several hundred times per second.
Why Do a Fatigue Test?
In many applications, materials are subjected to vibrating or oscillating forces. The behavior of materials under such load conditions differs from the behavior under a static load. Because the material is subjected to repeated load cycles (fatigue) in actual use, designers are faced with predicting fatigue life, which is defined as the total number of cycles to failure under specified loading conditions. Fatigue testing gives much better data to predict the in-service life of materials.