Controlling the electrical conductivity of fibre-polymer composites using z-pins

Carbon fibre composites have inherently high through-thickness electrical resistivity, which limits their application when high electrical conductivity is required. The use of z-pins to increase the through-thickness electrical conductivity of composite laminates is investigated in this paper. The through-thickness and in-plane electrical properties of a unidirectional carbon-epoxy laminate reinforced with carbon fibre composite or metal (copper, stainless steel, titanium) z-pins are characterised. Experimental tests and analytical model reveal that z-pins can increase the through-thickness electrical conductivity of the composite material by many orders of magnitude (up to 106). The through-thickness electrical conductivity can be controllably increased via the judicious choice of the material type and volume content of the z-pins. Large improvements to the through-thickness conductivity can be achieved without the z-pins altering significantly the in-plane conductivity of the composite material.