A Predictive Model for the Compressive Strength of 3D Woven Textile Composites

Abstract

The compressive response of 3D woven textile composites (3DWTC), that consist of glass fiber tows and an epoxy matrix material, is studied using a finite element (FE) based micromechanics model. A parametric Representative Unit Cell (RUC) model is developed in a fully three-dimensional setting with geometry and textile architecture for modeling the textile microstructure. The RUC model also accoutns for the nonlinear behavior of the fiber tows and matrix. The computational model is utilized to predict the compressive strength of 3DWTC and its dependence on various geometrical and material parameters. The finite element model is coupled with a probabilistic analysis tool to provide probabilistic estimates for 3DWTC compressive strength. I. Introduction hree-dimensional woven textile composites (3DWTCs) are gaining ever-increasing attention from various engineering sectors due to numerous structural advantages of the material system over conventional laminated composites 1-3 . Typical laminated composites have very good in-plane properties in the direction of the fiber tows, but tend to have low strength properties perpendicular to the fiber direction. The interfaces between the layers are the weakest link and delamnation is a common failure mode of laminated composites. Textile composites can have fiber tows in multiple directions and thus can have better properties in all loading directions. Through 3D weaving processes, 3DWTCs can implement Z-yarns woven around warp and weft fiber tows, improving the resistance to delamination failure dramatically. Advanced weaving technologies make the tow architecture tailorable to achieve desired mechanical performance for numerous applications. However, it is not easy to design and tailor 3DWTC for specific applications since it is very difficult to predict the mechanical performance of textile composites due to the complex textile architecture. Currently textile composites, especially with three dimensional architectures, are designed by an expensive build-and-test approach, which is a time consuming and costly process. There exists a stong need for a predictive model that is capable of reliably predicting mechanical performance of textile composites including basic stiffness and strength properties. In the present study, a finite element model for 3DWTCs is developed to predict the mechanical properties, specifically with a focus on compressive strength prediction. The modeling strategy, originally developed by Song et. al. 1 for two-dimensional tri-axially braied textile composites, will be extended here for 3DWTCs. They have shown good correlations with 2D in-plane woven systems for determining stiffness and strength properties, and also in describing progressive damage. The proposed model utilizes the true measured 3D geometry and nonlinear behavior of individual constituents to estimate compressive strength.