Optical Interferometric Study on Loading Hysteresis
Optical interferometric technique to reveal load hysteresis is discussed. Experiments indicate that progress of deformation in the plastic regime can be characterized by two features; material rotation and strain concentration. Interferometric fringe patterns (displacement contours) indicate these two features when applied to specimens previously loaded, and thereby can be used for diagnosis of load hysteresis. These features are consistent with analysis based on a field theoretical approach to deformation and fracture that is capable of describing all stages of deformation on the same theoretical basis. Finite element modeling based on the field theoretical approach reproduces interferometric fringes showing these features.