The damage detection system of CFRP structures by making use of electrical resistance changes due to elevated temperature is performed. CFRP is heated up by applying electric currents through the electrodes mounted on the surface of the structure. When the delamination occurs, the electrical resistance change due to elevated temperature becomes different from that of the other intact parts. In this study, therefore, the electrical resistance changes are measured at the multiple segments on a CFRP beam simultaneously, and the damage is detected from the change of relative relationship between the measurements. A set of electrical resistance changes is related with each other by means of a response surface, which changes when delamination cracks occur. The similarity of the response surfaces is evaluated by F statistics. These damage detection systems are applied to detect a delamination in cross-plied CFRP beam and the delamination is successfully identified.
