Crack under oscillating load

Fatigue testing, as described in ASTM E647, monitors the crack propagation in a specimen as it is subjected to an oscillating tensile load. The number of oscillations, N, used in these tests are typically in the millions of cycles. The purpose of the test is to monitor the crack propagation resistance under cyclical loading, a type of deformation to which most implants will be subjected (Baker, Bellare, and Pruitt 2003). 

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