Testing and modelling of lightning strike induced damage in CFRP wind turbine blade structures

Abstract

Carbon fibre reinforced polymer (CFRP) composite materials are increasingly used in the wind turbine (WT), aerospace, and automotive applications to reduce the structural weight of components. The introduction of CFRP components creates challenges when protecting structures from lightning strikes as they are semi-conductive in nature. CFRP materials facilitate conduction of heat and current in the fibre direction, but in the direction transverse to the fibres they have relatively low thermal and electrical conductivity resulting in significant Joule heating following a lightning strike. In a laminated polymer composite structure, the through-thickness conductivity is also low. Hence there is a build-up of voltage in the material, which eventually causes dielectric breakdown, allowing heat and current conduction to occur in the transverse and through thickness directions. Previous work [1,2] has mostly focused on aircraft structures subjected to lightning strikes, where the laminates are usually multidirectional and quasi-isotropic, which allows more in-plane conduction. In contrast, WT blade laminates are UD and more anisotropic, but the effects of lightning damage on their structural response has received limited research attention