Abstract
This study examines detailed damage mechanisms of CFRP laminate subjected to impulse lightning current by conducting experiment and numerical simulations. It is concluded that damage mechanisms of surface resin deterioration which cannot be simulated by past numerical studies can be explained by cross interaction effect of material insulation breakdown and directional creeping discharge due to strong electrical orthotropy of CFRP. High-speed camera observation shows rapid resin evaporation developed along surface fiber transverse direction resulting in surface resin deterioration damage. In order to explain this behavior, thermal–electrical coupling FEM analysis considering temperature dependent electrical property change due to resin sublimation and insulation breakdown was conducted. The result shows insulation breakdown strongly affects temperature distribution inside specimen due to Joel heating; on the other, temperature distribution in thickness direction was excessive than expected by experimental result. This fact indicates that part of applied impulse current was separated as creeping discharge and did not flow into specimen. To examine this phenomenon, electromagnetic field analysis with FDTD was conducted. The result shows current of creeping discharge is strongly affected and results in directional creeping discharge in transverse direction to fiber because of generated magnetic field due to strong electrical orthotropy of CFRP.
