Water uptake on lightning strike damage of carbon fiber reinforced composites with surface protections

The effect was examined of water uptake on the lightning strike (LS) damage of carbon fiber reinforced composites (CFRCs) and surface-protected CFRCs. First, water absorption (WA) experiments on CFRC, CFRC adhered to a copper mesh (CFRC-Cu) and CFRC bonded with an aluminum coating (CFRC-Al) were performed to obtain specimens with various water contents. Then, simulated LS tests were carried out on the specimens to investigate the LS damage mechanism. The experimental results showed that the LS damage level of the pristine CFRC specimens increased with the addition of water content, primarily due to the decreased glass transition temperature of the matrix, the increased longitudinal electrical conductivity and the gas explosion after WA. In terms of the CFRC-Cu specimens, the decreased interfacial properties between the copper mesh and the insulated adhesive layer are attributed to the aggravated LS damage area of the copper mesh, whereas the gas explosion is the key factor contributing to the increased damage in the CFRC-Al specimens. In addition, an increase in the adhesive layer thickness intensified the LS damage in the CFRC-Cu specimens but reduced the damage in the CFRC-Al specimens after WA.