Closed form solutions for predicting the elastic behavior of quasi-isotropic triaxially braided composites

In this paper we examine the mechanical behavior of a quasi-isotropic triaxially braided glass–fiber composite with an epoxy resin system containing a high bio-content. The effective properties are determined by using simple, discrete yarn and three-layer analytical representations of the quasi-isotropic braided layers. Analytical models are used to determine the elastic stiffness based on the constituent properties such as the fiber volume fractions, the waviness of the bias tows, and the relative thickness of the braided preform. The analytical models were compared to evaluate the effects of the braiding parameters on the overall stiffness values and the relative performance of each model relative to the system considered. The mechanical properties were measured with full-field methods and the results obtained were compared with the analytically obtained values.