In the present study, an electric resistance change method is adopted for the identifications of delamination crack location and size of CFRP laminates, and possibility of identification of delamination cracks is experimentally investigated by using cross-ply laminates. 3-point-bending tests to create delamination cracks are conducted using CFRP composite specimens with multiple electrodes, and electric resistance changes due to the delamination are measured. Response surfaces to estimate delamination location and size from electric resistance changes are constructed. In this method, stacking sequence and number of electrodes largely affect reliability of identification of the delamination location and size. In order to estimate these effects, a large number of experiments are conducted by using five kinds of specimens that have different stacking sequences and number of electrodes. As a result, the electric resistance change method can be useful for structures monitoring of laminate of various stacking sequences, and five electrodes are needed for high reliability.
