Identification of delamination crack of graphite/epoxy laminates by electric potential method for health monitoring

An electrical potential method is applied for identifications of size and position of delamination cracks of components of graphite/epoxy in the present study. The method does not cause strength reduction of structures, because the method adopts reinforcement fiber itself as sensors. Due to orthotropic electrical residence of laminates, electric potential fields of laminates are different from the fields of conventional methods for isotropic metallic materials. Authors have investigated the effect of orthotropic electrical resistance on the method by using FEM. Based on the results, identification of delamination crack size and position was impossible in the case of electric potential change of a structure is measured.In the present study, multiple points for measurement of electric potential are adopted for identification of the delamination crack size and position. The response surface methodology is adopted to obtain delamination size and position from electric potential change. Using FEM analysis, identification of the delamination crack size and position is conducted. As a result, a 5-segment-method is numerically shown to be very effective for identification of delamination crack size and position