This paper presents a physics based modelling procedure to predict the thermal damage of composite material when struck by lightning. The procedure uses the Finite Element Method with non-linear material models to represent the extreme thermal material behaviour of the composite material (carbon/epoxy) and an embedded copper mesh protection system. Simulation predictions are compared against published experimental data, illustrating the potential accuracy and computational cost of virtual lightning strike tests and the requirement for temperature dependent material modelling. The modelling procedure is then used to examine and explain a number of practical solutions to minimize thermal material damage.

, A. (2018). Understanding how arc attachment behaviour influences the prediction of composite specimen thermal loading during an artificial lightning strike test. Composite Structures.

A numerical approach is proposed and demonstrated for efficient modelling of the thermal plasma behaviour present during a lightning strike event. The approach focuses on events with time-scales from microseconds to milliseconds and combines the finite element method, Magnetohydrodynamics and Similitude theory. Similitude theory is used to scale the problem to require considerably less computing resource. To further reduce the computational burden and to resolve the numerical difficulty of simulating the nearly zero electrical conductivity of air at room temperature an approach based on cold field electron emissions is introduced. Simulations considering turbulent flow have been considered, modelling a test configuration from literature designed to inspect composite material performance and applying an aerospace standard test profile (waveform-B). Predicted peak temperatures (of the order of ~40,000 K) and pressures (of the order of 0.1-0.2 MPa) suggest that the pressure loading during a waveform-B event will have a minimal effect on composite material damage.

Experimental work has shown that a component of lightning strike damage is caused by a mechanical loading. As the profile of the pressure loading is unknown a number of authors propose different pressure loads, varying in form, application area and magnitude. The objective of this paper is to investigate the potential contribution of pressure loading to composite specimen damage. This is achieved through a simulation study using an established modelling approach for composite damage prediction. The study examines the proposed shockwave loads from the literature. The simulation results are compared with measured test specimen damage examining the form and scale of damage. The results for the first time quantify the significance of pressure loading, demonstrating that although a pressure load can cause damage consistent with that measured experimentally, it has a negligible contribution to the overall scale of damage. Moreover the requirements for a pressure to create the damage behaviours typically witnessed in testing requires that the pressure load be within a very precise window of magnitude and loading area.

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