Prediction of Lay-Up and Stacking Sequence Effects on the Mechanical Resistance to Simulated Lightning Strike

In protected carbon fibre-reinforced polymer laminates subjected to simulated lightning strike, while thermal effects mostly affect the topmost UD plies, damage in the bulk, where temperatures can be far from the ablation temperatures of the composite constituents, is mainly the result of the explosion of the lightning protection layer, the supersonic plasma expansion shock waves, and the magnetic forces. In this work, previously validated three-dimensional models are applied to the analysis of lay-up and stacking sequence effects on the mechanical damage induced by simulated lightning strike on carbon/epoxy multi-directional laminates and compared with experimental observations in the literature. This work demonstrates that those observations can be replicated by the proposed models, predicting the effect of lay-up and stacking sequence not only on the orientation of mechanical damage, but also on its size. In addition, no effect on damage depth is predicted, which is also in agreement with available experimental observations. Finally, the models predict that laminates with thicker ply blocks have larger mechanical damage projected areas, which is also in agreement with experimental observations in the literature. While the previous literature had focused on the effect of the lay-up and stacking sequence on thermally induced damage, this work is a first attempt to predict those effects on the mechanical resistance, which in the future will be key to assessing lightning damage tolerance in protected composite laminates.