The present paper deals with a new lamination theory to calculate electric current between two probes on Carbon Fiber Reinforced Plastic (CFRP) laminates. Unidirectional CFRP has strongly orthotropic electric conductance. When electric current is applied on a surface of a CFRP plates using two probes, the electric voltage field is uniform for thin CFRP plate and is not uniform in the cross section for thick CFRP. The electric current concentrates near the surface where the electric current is applied for thick CFRP laminates. In the present study, a lamination theory for thin CFRP laminates is discussed first. After that, a new lamination theory for thick CFRP laminates is proposed here. The theory for thick CFRP plates adopts non-uniform electric voltage in the thickness direction. For the non-thick and non-thin (middle thickness) CFRP plate, an approximation method is proposed here. To obtain the shape of the non-uniform voltage distribution, the analytical results of a thick single-ply of the previous paper is adopted as a contribution function to calculate the effective conductance of the thick CFRP laminate. Cross-sectional 2-D FEM analysis is used to obtain the contribution function for non-thick CFRP plates. The proposed methods are applied to two cases of a thick CFRP plate, and the results are compared with the 3-D FEM results. As a result, the new lamination theory is proved to be efficient for thick CFRP plates.
