Statistical Evaluation of Modified Electrical Resistance Change Method for Delamination Monitoring of CFRP Plate

The present paper employs the electric resistance change method for monitoring the location and size of a delamination crack in graphite/epoxy composite laminates. The authors have revealed that the electric resistance change method with response surfaces is very effective experimentally and analytically. For the estimations of delamination locations, however, large error of the estimations still remains. FEM analyses revealed that the standardizations of the electric resistance changes are very effective to obtain high performance identifications. In this study, the new electric resistance change method of high performance identification of delaminations is applied to a plate-type specimen with an embedded delamination of cross-ply and quasi-isotropic laminates. Ten electrodes made from copper foil are mounted on the specimen top surfaces. The electric resistance changes are measured using a conventional strain gage amplifier. Response surfaces are adopted as a tool for solving inverse problems to estimate the location and size of delamination crack from the measured electric resistance changes of all segments between electrodes. Statistical analysis was performed to result of identification using the response surface. As a result, the present method successfully provides estimations of location and size of the embedded delamination for graphite/epoxy laminated composites.