Lightning damage prediction to carbon fiber composite laminates driven by thermal-chemical-mechanical coupling

During a lightning strike, various mechanical loadings induced by lightning arc contribute to the degradation and failure of composites. So far, numerical research has mainly concentrated on modeling the resistive heating with or without consideration of certain thermal induced mechanical effects. This paper aims to develop a fully coupled thermal-chemical-mechanical finite element model to investigate the lightning-induced dynamic response and mechanical damage in carbon fiber reinforced polymer (CFRP) laminate under coupled effects of thermal ablation and comprehensive loadings from acoustic pressure, electromagnetic force and thermal expansion. The FE prediction is successfully validated with preceding experimental and numerical results available in the literature. The results quantify the potential contribution of mechanical loadings resulting from acoustic pressure, electromagnetic force and thermal expansion on dynamic response and damage.The predicted dynamic response shows that the acoustic pressure and thermal expansion occupy the main contribution to negative deflection at both sides of laminate whereas in the central region of laminate, the thermal expansion plays a leading role in the generation of positive deflection. The impact of mechanical loadings on in-plane damage of laminate is stronger than in-depth damage which however, is dominated by thermal ablation effect with its contribution of 86%. The predicted damage under various mechanical loadings suggests the consideration of thermal expansion makes a remarkable increment in matrix and delamination damage areas with their corresponding contribution of 104% and 108% whereas the presence of acoustic pressure and electromagnetic force tends to weaken these damages.