Thickness scaled compression tests in unidirectional glass fibre reinforced composites in static and fatigue loading

Abstract Thick laminates can be found in different wind turbine blade sections, such as the root or the spar caps. However, static and fatigue design of thick laminate components is based on thin coupons tests (around 4 mm thick) and safety coefficients determined by the guidelines and standards. The aim of this work is to study the size effect in compression for unidirectional glass fibre reinforced composites. Scaled static and fatigue compression tests were performed on glass/epoxy laminates of 4 mm, 10 mm and 20 mm thick. A series of scaled coupons were designed taking into account the influence of the manufacturing process and the final testing conditions. While static tests on laminates with different thicknesses showed no significant change in the static ultimate stresses, fatigue tests showed a decrease in the fatigue life for increasing thicknesses as well as wider intervals of confidence. In addition, fatigue data were compared with the reduced fatigue capacity reported by the design guidelines showing reserve factors larger than 2.0.