Pure and simple: investigating the in-plane shear kinematics of a quasi-unidirectional glass fiber non-crimp fabric using the bias-extension test

This paper concerns shear testing of a quasi-unidirectional non-crimp fabric used for wind turbine blades. In this context “quasi” refers to the fact that the majority of the reinforcement is oriented along the longitudinal direction with a small amount acting as a stabilizing backing layer in the ± 80∘ direction. The bias-extension test is used to investigate the in-plane shear kinematics of the fabric, i.e. whether a pure or simple shear kinematic is more suitable. Further, an expected outcome of the test is a maximum applicable shear angle. Such information is highly important when simulating the draping of the fabrics in a blade mold. The investigation shows that the fabric deforms mostly in pure shear for the shear angles relevant for wind turbine blade production.