Role of interlaminar interface on bulk conductivity and electrical anisotropy of CFRP laminates measured by eddy current method

The purpose of this paper is to deal with the characterization of bulk electrical conductivity in multilayer carbon fiber reinforced polymer (CFRP) laminate by using eddy current method. The correlation between probe signals and conductivities in different directions of unidirectional CFRP is obtained with the aid of numerical code, which is based on finite element method in terms of magnetic vector potential. The effect of interlaminar interface on the bulk conductivity of CFRP laminate is investigated by visualizing the lift-off curves of probe signal in complex plane. It is found out that the cross-ply laminate has much better electrical conductance than unidirectional plate, and the bulk conductivity of CFRP laminate depends mainly on the number of current paths produced by the overlapped fibers at the interfaces between two angled layers. In addition the polar diagrams of T-R probe signals at multiple angular positions are depicted to characterize the anisotropy of CFRP laminate.