LSP FOR THIN CFRP STRUCTURES - A DAMAGE TOLERANT DESIGN APPROACH

摘要

For thin-walled CFRP structures not containing systems or fuel in combination with thick paint it was found that the usual 'No Puncture'-substantiation philosophy for Direct Effects of lightning strike can be both impractically conservative and even oversimplified. Skins would need to be substantially reinforced (weight & cost increase), but still their protection system could exhibit a threshold behaviour when marginally overshooting in paint thickness (drastic change in failure mode when exceeding a certain paint thickness). Moreover, a non-penetrated skin may still exhibit substantial damage, potentially leading to a barely detectable deterioration in strength. In order to still guarantee safe behaviour of these thin composite structures in case of lighting attachment, a damage tolerant 'Local Damage only'-philosophy was adopted where it was possible to omit dedicated LSP materials under specific conditions. This paper aims to explain why and how.