Prediction Model of Gas Expansion and Electro-Thermal Coupling regarding Lightning Damage to Carbon Fiber Composites

When carbon fiber reinforced polymer composites are struck by lightning, they are subjected to a combination of high-temperature ablation and gas expansion. To accurately predict the lightning damage area, the damage area of carbon fiber under different amounts of Joule heating was obtained through experiments, and a simulation analysis of electro-thermal coupling and gas expansion was performed. The simulation of electro-thermal coupling showed that the damage area of carbon fiber in the simulation accounts for 67% in the experiment at low energy, but there is a large gap between the two at high energy, with the former accounting for only 28.2% of the latter. Combining the effects of Joule heating and gas expansion and introducing the conversion efficiency of the Joule heat to the kinetic energy of gas, a damage prediction model of electrical-thermal–mechanical coupling was finally established. The calculation results of the composite model show that the maximum error between the model and the lightning test at high energy was only 12.5%. It was found that Joule heating has a greater impact on lightning damage at low energy, while gas expansion was the main factor in determining the damage degree of carbon fiber under the condition of high energy.