Nonlinear electrical conductivity characteristics under high impulse current and applications to lightning strike damage simulation for CFRP laminates

This experimental investigation assessed conductive properties of quasi-isotropic CFRP laminates in the thickness direction under high impulse current and clarified the properties’ effects on lightning damage behaviours. For CFRP laminates with interleaf resin layers (T800/3900-2B), experiments confirmed that conductivity in the thickness direction increases irreversibly with applied impulse current (approx. 5.3 kA, approx. 3.2 kV). However, the conductivity of CFRP laminates without interleaf resin layers (T800/2592) changed little during testing. Nonlinear conductive behaviour was applied to lightning strike damage numerical simulations using a coupled thermal–electrical analysis and heat transfer analysis. For numerical analyses, shape and dimensional changes of the applied current on the specimen surface were considered based on high-speed observations made during simulated lightning strike testing. The pyrolysis region calculated using damage analysis agrees well with experimentally obtained results when considering the potential gradient dependence of conductivity: better agreement was obtained than when calculated under a constant value.