Finite Element Analysis of Lightning Damage Factors Based on Carbon Fiber Reinforced Polymer

Abstract

While carbon-fiber-reinforced polymers (CFRPs) are widely used in the aerospace industry, they are not able to disperse current from lightning strikes because their conductivity is relatively low compared to metallic materials. As such, the undispersed current can cause the vaporization or delamination of the composites, threatening aircraft safety. In this paper, finite element models of lightning damage to CFRPs were established using commercial finite element analysis software, Abaqus, with the user-defined subroutines USDFLD and HEAVEL. The influences of factors such as the structural geometry, laminate sequence, and intrinsic properties of CFRPs on the degree of damage to the composites are further discussed. The results showed that when a current from lightning is applied to the CFRP surface, it mainly disperses along the fiber direction in the outermost layer. As the length of the CFRP increases, the injected current has a longer residence time in the material due to the increased current exporting distance. Consequently, larger amounts of current accumulate on the surface, eventually leading to more severe damage to the CFRP. This damage can be alleviated by increasing the thickness of the CFRP, as the greater overall resistance makes the CFRP a better insulator against the imposed current. This study also found that the damaged area increased as the angle between the first two layers increased, whereas the depth of the damage decreased due to the current dispersion between the first two layers. The analysis of the electrical conductivity of the composite suggested that damage in the fiber direction will be markedly reduced if the conductivity in the vertical fiber direction increases approximately up to the conductivity of the fiber direction. Moreover, increasing the thermal conductivity along the fiber direction will accelerate the heat dissipation process after the lightning strike, but the influence of the improved thermal conductivity on the extent of the lightning damage is less significant than that of the electrical conductivity.

The Influence of Carbon Fiber Composite Specimen Design Parameters on Artificial Lightning Strike Current Dissipation and Material Thermal Damage

“…Specimen size and stacking sequence effects are known to influence experimental damage. Simulation research most often attempts to replicate experimental work, and is thus not generic as the results are specific to the specimens because of stacking sequence and distance to ground effects [48]. Previous works have also conducted a variety of studies on the impact of modifying various aspects of lightning strike simulations on resulting damage [5,16,33,43] but none have quantified the current dissipated from each ply in the specimen.…”

“…While the effect of changes to ground boundary condition on predicted thermal and mechanical damage has been studied [16], to best knowledge there has been little comparison on the effect of specimen shape and size on damage. Recently, Zhu et al [48], using square specimens, compared the effect of specimen thickness (from 1 mm to 7 mm) and specimen side length (from 37.5 mm to 300 mm) on predicted damage. Zhu et al [48] proposed that the distance to ground is a key factor influencing Joule heating and the resulting damage.…”

“…Recently, Zhu et al [48], using square specimens, compared the effect of specimen thickness (from 1 mm to 7 mm) and specimen side length (from 37.5 mm to 300 mm) on predicted damage. Zhu et al [48] proposed that the distance to ground is a key factor influencing Joule heating and the resulting damage. The distance to ground can be described as the distance from the arc attachment point to the zero electrical potential boundary at the edge of the test specimen or the length along a conducting path from the strike location to a grounded support condition.…”

“…In this selected example, the damage produced by Kawakami (~3900 mm 2 ) was more confined to the centre of the specimen without extension to its extremities, unlike Hirano's damage (~2595 mm 2 ) measurements. Recently, within simulations, Zhu et al [48] [48] found that when the angle between adjacent plies was increased, damage area decreased and suggested that current could disperse more widely, resulting in a reduction in Joule heating. These findings were established for a fixed specimen.…”