Damage zoning characteristics of composite laminates with different protections subjected to lightning strike

Lightning strike tests of composite laminates with different protections were conducted based on the combining strikes of four standard waveforms A+B+C+D. The interaction procedure between the lightning channel and composite laminate surface was analyzed, and the surface damage area of composite was divided into initial attachment area, attached conduction area, attached expansion area, reattachment area and swept damage area with respect to the physical characteristics of lightning channel. And the damage characteristics were analyzed for four types of laminates: unprotected reference specimen, partial and full-scale spraying aluminum specimens, and copper grid specimen. The results show that the surface damage of composite is induced by the interactions of thermo-electrical physical properties of lightning channel, surface thermo-electrical properties of composites, and charge distribution in strong electromagnetic field. The characteristics of symmetry and zoning of damage area on surface of composites are affected by spraying shape, thickness and homogeneity of aluminum layer. The rough surface of composite laminates induced by copper grid protection leads to the complexity of surface damage zoning. The accumulation characteristic and homogeneity of distribution for the induced charge on surface of composite laminates are the direct reasons for distributions of reattachment area and swept damage area. The primary damage forms of composites subjected to the lightning strike include fiber sublimation, rupture and fuzzing, the matrix charring melting and ablation, the delamination and detaching of materials, and the melting, vaporization and breakdown of protective materials. The analysis results can be applied to the qualitative design for lightning protection of composites.