This study examined lightning strike damage to CF/toughened epoxy and CF/epoxy composites to understand the role of inter-laminar toughened layers. An impulse electric current of 40 kA with negative polarity, in accordance with SAE ARP 5412B, was applied to CF/toughened epoxy, CF/epoxy, and aluminum specimens. Temperature response on the rear surface of these specimens was measured using an IR camera during arc entry tests. Compared to CF/epoxy, CF/toughened epoxy suffered damages such as carbon fiber breakage and delamination. Electrical conductivities through the thickness of CF/toughened epoxy and CF/epoxy were measured to be 0.0809 S/m and 15.1 S/m, respectively. Cross-sectional observation results revealed that the inter-laminar toughened layer affects through-thickness electrical conductivity. These results suggest that the inter-laminar toughened layer affects impulse current conduction paths in these materials, leading to varied damage on the rear surface or heating rate.
