An Analytical Model for Predicting the Elastic Properties of Triaxially Braided Composites

Abstract

Based on the iso-strain and interfacial continuity conditions, an analytical model for the prediction of the elastic properties of triaxially braided composites was proposed. The model considers the variation of the braider yarns' undulation period in particular areas. Triaxially braided composites using two fabric architectures have been fabricated and tested in tensile mode to verify the model. Parametric studies have been performed to analytically quantify the effects of the braid angle and the ratio between axial yarn and braider yarn size on the in-plane elastic properties of the composites. Increasing the braid angle leads to a decrease in the longitudinal modulus, an increase in the transverse modulus; it also causes the in-plane shear modulus to peak at a braid angle of about 508, and Poisson's ratio to peak at a braid angle of about 358. Increasing the ratio between axial yarn size and braider yarn size leads to an increase in the longitudinal modulus, and decreases in the transverse modulus, in-plane shear modulus, and Poisson's ratio.