Numerical analysis of the heat transfer properties of z-pinned composites

The controlled increase of the through-thickness heat transfer properties of fibre reinforced polymer composites using z-pins is demonstrated using finite element (FE) modelling. The modelling reveals that the through-thickness thermal diffusivity of composite materials can be tailored to a specific value via the judicious choice of the volume content and thermal conductivity of z-pins. The effects of the volume content (up to 5%) and material type (carbon fibre composite, steel, titanium, copper) of z-pins on the through-thickness and in-plane thermal diffusivities of a carbon-epoxy composite is analysed. The through-thickness thermal diffusivity of the composite increases linearly with the z-pin content, and this is because the pins act as a thermally conductive pathway. The through-thickness thermal diffusivity value of the composite also increases with the thermal conductivity of the z-pin, however with an accompanying increase to the amount of lateral heat transfer. FE modelling reveals the thermal properties of composites in the in-plane directions are not affected significantly by z-pins. This study reveals that z-pinning is a novel approach to increase the through-thickness heat transfer properties of composites.