Electrical transients during interfacial debonding and pullout of a metal rod from an epoxy matrix

We examine electrical transients which are produced during the propagation of a debonding crack along the interface of an axially loaded stainless-steel rod embedded in epoxy. Time-resolved correlations with fracto-emission signals and tensile strain in the rod are made to assist interpretation. We show that on microsecond time scales, the motion of the debonding crack as well as the initial pullout motion of the rod following debonding can be detected and followed. A model is developed which consistently describes the sign and amplitude of the detected electrical signals. These experimental data provide time-resolved information on the sequence of events leading to interfacial fracture and initial pullout of the rod from the epoxy.