Lightning damage assessment into composite based on surface explosion and fiber breakage

International audienceLightning damage mechanism for composite aircraft structure is a complex multi-physical phenomenon. The lightning current entering into the surface metallic protection and the carbon plies generates Joule’s effects and electromagnetic forces which both induce mechanical forces and surface explosion that produce a significant mechanical impact. The explosion of the lightning strike protection has been recorded through the measurement of the vaporization profile evolution in space and time using transparent glass epoxy substrates. In this paper, this profile is combined to shock wave model developed by the study of electric explosion on wire equivalent to web of ECF. The second important phenomenon is fiber breakage due to current flow in CFRP. This has been assessed through specific lightning test measuring the current distribution between CFRP and LSP depending on the paint thickness. It is aimed is this paper to present the tests setup and observations. Those two loading components have been injected into a mechanical model using Abaqus Explicit® in order to assess the damage ignition and propagation in the composite thickness as a function of time. Simulations are similar to previous studies but use real tests measurements for the pressure evolution instead of an impulsion induced estimation. Results of the simulations are confronted with laboratory lightning tests. Deflection as functions of time has been measured thanks to stereo correlation devices. Simulated damage distributions are compared to post-mortem non-destructive and destructive measurement in the core of the composite plates