On a Consideration to the lower limit of fatigue

摘要

Predicting the onset of an early stage in fatigue process as precursory phenomena is an important problem to diagnose the integrity of equipments and structures. The essential mechanisms of fatigue are the slip and multiplication of dislocations under cyclic loading. On the other hand, the nonlinearity in stress-strain relation arisen from the existing dislocations in a material generates the higher harmonics in the vibration of materials in resonance and detection of the higher harmonics is to become a means to evaluate the stage of fatigue process in progress. In this study, the consideration on relating the dislocation dynamics to higher harmonics observed during fatigue process has been done.