Spatial electric potential distributions and damage mapping in 3D carbon fiber/epoxy angle-interlock woven composites with different current directions

Exploring electric potential distributions in carbon fiber reinforced polymer composites (CFRPs) is important in electrical-based structural health monitoring for in situ damage detection. Here we investigate influences of current injection angles, electrode locations, and current injection pairs on the electric potential distributions in 3D carbon fiber/epoxy angle-interlock woven (AIW) composites. We have conducted different types of electric potential measurements and established a linear anisotropic conductivity model to reveal the electric potential distributions. It was found that the curved warp yarns form many contacts and increase the conduction path, leading to lower electric conductivity and flatter potential field than those of the weft yarn with straight alignment. The orientation and value of surface electric potential field change depend on current flow direction caused by current injection mode (CIM) and conduction mechanism due to yarn arrangement. Oblique current directed at an angle of 45 degrees is more sensitive in indicating interior damage than that of current parallel to the yarn direction. It is recommended that the oblique current injection should be used to provide effective damage sensing for CFRPs with complex structures.