Numerical simulations of lightning strikes to carbon fiber reinforced polymers using a multi-variable approach

Carbon fiber-reinforced polymer (CFRP) composite materials are being employed widely in the manufacturing of next-generation aircraft because of their superior mechanical properties compared to those of metallic-based materials. Owing to growing interest in CFRP materials from large commercial and military aircraft manufacturers, such as Boeing and Airbus, research that investigates lightning strikes and associated damage is of paramount importance, as the fiber-polymer composite is highly resistive to electrical current. The high resistivity of traditional CFRP materials means that they are susceptible to extreme damage caused by the Joule effect, also known as resistive heating. The aim of the study presented in this paper is to determine and quantify the effectiveness of a developed multi-variable pyrolysis approach to model the transient material degradation during a lightning strike event. The study employs the finite element method (FEM) in the form of a coupled thermal-electrical analysis in conjunction with a user subroutine available in Abaqus. A parametric study was conducted to compare three different peak current values (20kA, 30kA and 40kA) based on a model that utilized pyrolysis-dependent material constituents as well as a novel model for specific heat capacity. The study also included a heat transfer step for a cool-down process. The results obtained from the model developed have strong agreement with the surface damage area and depth of damage compared with those from experimental analysis in literature.