Optical interferometric study of fatigue fracture based on deformation wave theory

This study explores the physical mechanism of fatigue fracture using electronic speckle pattern interferometry (ESPI) and a wave theory of deformation and fracture. ESPI forms the contours of differential displacement of solid objects under deformation at each time step as optical interferometric fringe patterns. The wave theory indicates that the initiation of total fracture is similar to the transition from glow to arc discharge in gas media. In a gas discharge, both displacement current (energy conservative) and conduction current (energy dissipative) can carry the electromagnetic energy between the electrodes. In the transition to arc discharge, the conduction current becomes the dominant energy carrier. Our study indicates that a specific fringe pattern is analogous to a conduction current and is responsible for fatigue fracture.