Effect of Yarn Waviness on Strength of 3D Orthogonal Woven CFRP Composite Materials

Abstract

A curved beam model is presented for studying the effect of fiber yarn waviness on the tensile strength of woven composite materials. In the model, a curved beam is assumed to be supported, with an elastic tension or shear foundation in a woven composite material, either with the open-mode type or with the shear mode type. By using the maximum stress criterion in a fiber yarn, the ultimate tensile strength of a woven composite material can be determined together with the failure location. The curved beam modeling procedure is then utilized to predict the ultimate failure stress of the 3D orthogonal woven composite materials when subject to a tensile load in the filler direction. For the open-mode type or shear mode type, a good agreement is found between the measured and predicted failure stress in the filler direction for the 3D orthogonal woven CFRP composite materials. A parametric study shows that the failure stress in the filler direction is remarkably affected by the span length and the amplitude of the filler yarn waviness, and slightly affected by the volume fraction of the z yarn and the Young's modulus of resin matrix. The height and width of the filler yarn do not seem to affect the failure stress in the filler direction.