A Multiphysics Simulation Approach for Efficient Modeling of Lightning Strike Tests on Aircraft Structures

Abstract

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.

Modelling of mechanical failure due to constrained thermal expansion at the lightning arc attachment point in carbon fibre epoxy composite material

“…From the preceding lightning strike thermal electric simulations [18,[20][21][22][23][24][25] composite specimen materials reach high temperatures, > 1,000˚C, over short time periods, < densities of the order of GW/m 2 applied over milliseconds [31][32][33][34][35]. In these works maximum surface temperatures reached are between 2,000 and 3,000˚C.…”

“…Using the FE method and employing explicit thermal-electric analysis, it is possible to model the temperature generation and temperature transfer due to resistive heating from electrical arc loading [18,[20][21][22][23][24][25]. Herein the thermal-electric analysis is carried out in ABAQUS Explicit and uses C3D8R elements.…”

“…This approach thus enables the representation of a moving filament of arc at the centre of an expanding arc. As limited experimental data is available which defines accurately the arc attachment behaviour the modelled behaviour is based on the general experimental description of behaviour during testing [11] and plasma simulation work of similar test setups [8,20]. Further it is initially ACCEPTED MANUSCRIPT assumed that half the total electric load is associated with the moving arc component and half associated with the expanding arc component [25].…”

“…However, there is still limited understanding of the mechanisms during a lightning strike which lead to damage, partly due to the complex thermal, electrical, electromagnetic and mechanical components of the event [19][20][21], and partly due to the limited number of artificial lightning strike tests which have been published. The major challenge with testing is the speed and intensity of a lightning strike which makes it very difficult to directly acquire high resolution physical measurements during a test [13].…”

Quantifying the Influence of Lightning Strike Pressure Loading on Composite Specimen Damage

“…In summary it is not possible to isolate the different proposed aspects of the pressure loads. Authors have until now used novel experimental setups and MHD simulations [37] to understand the loading pressure present during a test. Generally the literature suggests that pressure radically varies in time and magnitude.…”