Assessing the potential of graph-based modelling for lightning damage in aerospace CFRP structures via high-resolution X-ray tomography

Carbon-fibre reinforced polymer (CFRP) structures are increasingly adopted in aviation to reduce weight while maintaining high mechanical performance. A major challenge for these composites is lightning strikes: intense transient currents can trigger coupled electro-thermal-mechanical effects and generate complex internal damage, notably three-dimensional delamination networks. While high-resolution X-ray Computed Tomography (CT) can reveal these networks, turning volumetric observations into an interpretable representation that helps trace plausible post-strike current pathways remains difficult. This study explores an end-to-end strategy that leverages lightning-induced delaminations as informative traces to approximate current corridors. From CT volumes, delaminations are reconstructed and converted into a weighted graph capturing topology and geometric attributes. Preferential routes between conductive features (e.g., fasteners) are then estimated through path-based optimisation. The approach is first validated on simulated CT images with controlled geometries and mastered properties, and subsequently applied to CFRP coupons subjected to laboratory lightning strikes to recover realistic delamination pathways. By moving from voxel-level damage to a compact network representation, the proposed approach provides quantitative descriptors of connectivity and preferential paths for comparative damage assessment and physics-guided lightning direct-effect modelling.