The Effect of Ply Waviness for the Fatigue Life of Composite Wind Turbine Blades

Abstract

Wind turbine blade failure is one of the most prominent types of damage occurring in operating wind turbine systems. Glass fibre materials are mainly used for producing wind turbine blades and they consist of large tows, stitched fibres, which are prone to generate imperfections such as ply waviness. The primary objective of this research was to evaluate the effect of ply waviness on fatigue life of typical composites used in wind turbine blades. This study involves two main areas: Finite elements analysis (FEA) and experimental testing. The Finite element analysis was carried out using the commercial code from ESI group. The experimental work was carried out by manufacturing specimens from glass fibre with regular waviness and testing for static and fatigue failure. The tensile static test data was used to identify the effect of ply waviness for failure strength. Cycles to failure (S-N) curves were developed for two different wave profiles based on fatigue testing data. The long term aim of this ongoing research is to improve current fatigue life estimation methods applicable to composite wind turbine blades.