Abstract
Digital image correlation is applied to measure displacement and strain fields around a crack tip in a polycarbonate plate specimen. From the displacement data obtained by digital image correlation, stress intensity factor and J-integral on arbitrary paths are calculated. The measurement results show that localized strain region appears at a crack tip before crack initiation and that the strain region propagates forward of the crack tip. After formation of the strain region, the stress intensity factor of the crack increases remarkably and J-integral depends on integral paths due to formation and propagation of plastic zone.
