Simulating lightning effects on carbon fiber composite shielded with carbon nanotube sheets using numerical methods

The demand for lightweight aircraft structures has shifted from traditional metals like aluminum to composite materials such as carbon fiber reinforced polymers (CFRP) to achieve weight reduction. However, this transition has led to decreased lightning strike protection efficiency due to the dielectric nature of CFRP. To address this problem, two CFRP samples-one unprotected and the other shielded with carbon nanotube (CNT) sheets-were subjected to artificial lightning strike testing. The research employed a coupled thermal-electrical finite element analysis method to investigate the lightning strike's impact and damage mechanisms on both samples. The numerical results closely aligned with published experimental data, validating the simulation. Unprotected CFRP sustained damage through the thickness direction up to 8 composite plies and inplane direction over a length of 110 mm. In contrast, the sample protected with CNT sheets exhibited damage limited to the surface of the first 4 plies, with in-plane damage reduced to 24 mm. Notably, the damage area in the CFRP protected with CNT sheets showed a substantial 78.1 % reduction compared to the unprotected CFRP sample. This suggests that CNT can enhance the electrical conductivity of CFRP when incorporated between interlayers in both in-plane and thickness directions. The study enhances understanding of CFRP damage behavior and failure modes under lightning strike conditions, emphasizing CNT sheets as an improved and viable lightning strike protection system for aerospace applications, warranting further investigation.