Experimental testing method to characterise the drapability of UD non-crimp fabrics used in wind turbine blades

This scientific article presents a novel approach for characterising the drapability of fabrics used in wind turbine blade production. This study defines drapability as an intrinsic property of fabric to shear. Specifically, it refers to the potential of the rovings to slide with respect to each other. The evolution of wrinkles has been quantified by the ratio of height-to-width corresponding to a shear angle. The growing industrial interest in binder fabrics, for their preforming ability and improved handling leading to faster blade production, has motivated this study. In this research, two types of non-crimp fabrics, with and without binder, were analysed to study the evolution of wrinkles concerning applied shear angles. A state-of-the-art 3D blue light scanning technique is employed to accurately measure the aspect ratio (height/width) of wrinkles at various shear angles, including 0°, 4°, 6°, 8°, 12°, and 16°. A wrinkle having an aspect ratio of 1/10 was determined to correlate with an applied shear angle of 9° for non-binder fabrics, and 3° for binder-based fabrics. The findings clearly demonstrate the influence of binders on fabric drapability, reducing it by a factor of three. These results provide valuable insights into the influence of different parameters on wrinkle formation, aiding in controlling these factors to avoid manufacturing defects in wind turbine blades.