Models for Predicting Thermomechanical Properties of Three-Dimensional Orthogonal Woven Composites

Unit cell and laminate modeling approaches were previously developed for predicting the effective elastic constants of three-dimensional (3D) orthogonal woven fabric composites [1]. For both models, the finite element analysis (FEA) and theoretical analysis methods were proposed. In the FEA method, finite element meshes were generated using the commercial FEA software Strand6, while in the theoretical analysis methods, closed-form formulas were derived using elastic mechanics theory and the "X model," "Y model" and "Z model" [2]. In this paper, both the unit cell and laminate modeling approaches were used to predict the effective coefficients of thermal expansion (CTEs) for 3D orthogonal woven fabric composites. The present numerical study showed that there is a good agreement between the FEA and theoretical analysis results. Also, a good agreement was noted between the present predicted results and experimental results available in the literature. Parametric studies were conducted to investigate the effects of the yarn cross-sectional shape, lamina block layer number, lamina block thickness, through-the-thickness (or z) yarn volume fraction and its space (i.e., space between two adjacent z yarns) on the effective coefficients of thermal expansion. It is worth pointing out that the theoretical models and the relevant formulas for predicting the effective coefficients of thermal expansion can also be used to predict the effective coefficients of moisture expansion for 3D orthogonal woven fabric composites.