Multi-prove electric potential change method for delamination monitoring of graphite/epoxy composite plates using normalized response surfaces

Delamination is a significant defect of laminated composites. The present study employs an electric potential change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing graphite fibres as sensors. In our previous paper, a two-prove method was adopted for the electric-resistance change measurements because of the simplicity. The two prove method is not appropriate for a precise measurement, and it tends to include a large experimental error in the electric resistance change owing to the electric resistance change at the electrodes. Instead, the present paper employs a multiple-prove method for the measurements. In the present study, high precise measurement system of electric voltage change is developed, and the electric voltage measurement method is adopted for identification of embedded delamination location and size. Measured electric potential data are normalized for creations of response surface to identify the delamination. As a result, the new multi-prove electric potential method is shown to be effective for the identifications of embedded delamination cracks of graphite/epoxy composite laminates.