An electric resistance change method is successfully applied to the delamination detections of CFRP laminates. In the present study, orthotropic electric resistances of CFRP laminates are measured experimentally of three volume fractions of carbon fiber. The experiments in the present paper reveal significant change of the electric conductance values in the transverse direction and thickness direction owing to small change of the volume fraction. On the basis of the measured orthotropic electric conductance, the effect of the electric conductance is investigated in detail here. The effect of the orthotropic electric resistance change on electric resistance measurements for delamination detection is investigated using FEM analyses. For the analyses, beam type specimens of cross ply laminates are employed. Two types of stacking sequence are [0/90]s and [90/0]s. Electric resistance change owing to a delamination is discussed for both types of the specimens on the basis of the results of the electric current density diagrams. Results obtained are followings. (1) Electric resistances of thickness direction and transverse direction change significantly due to the small change of fiber volume fraction. (2) The mechanism of delamination detection with electric resistance change method was elucidated. (3) Electrodes should be mounted on fiber direction.
展开▼
