Comparison of lightning protection performance of carbon/epoxy laminates with a non-metallic outer layer

This study shows how a lightning protection layer can be designed to effectively mitigate lightning damage in underlying composite structures. A parametric study was performed to characterize critical lightning protection layer properties that improve composite lightning damage resistance. Simulated 50 kA and 200 kA lightning strikes to pitch-based carbon fiber paper (PCFP)-protected AS4/3506 carbon/epoxy composites were considered in this study. The lightning protection characteristics of various PCFP outer layers were assessed by varying in-plane and through-thickness properties: electrical and thermal conductivities, and electrical and thermal gap conductances. The predicted matrix decomposition in the outermost AS4/3506 ply was significantly reduced by increasing the PCFP in-plane electrical conductivity. While predicted lightning damage decreased slightly with a decrease in thermal gap conductance, varying the electrical gap conductance and the in-plane and through-thickness thermal conductivities did not significantly affect the damage development. Among various PCFP properties, the PCFP in-plane electrical conductivity was the most critical factor in reducing thermal damage development (thus, protecting the underlying AS4/3506 laminate). This parametric study demonstrates that it may be possible to tailor lightweight non-metallic lightning protection layers as an effective alternative to traditional metallic projection layers.