Three‐dimensionally woven and braided composites. I: A model for anisotropic stiffness prediction

Abstract A model for the prediction of anisotropic elastic stiffness of 3‐D textile structural composites based on the preform architecture and the preforming process parameters is presented. The methodology presented in this paper uses a preform model to represent the fiber microstructure and employs a micro‐mechanical analysis to determine the macroscopic anisotropic stiffness. Representative volume elements (macro‐cells) are identified for three‐dimensionally woven and braided preforms and geometric descriptions of the path and interactions between the tows within the cells are generated. This geometric modeling enables the estimation of the fiber volume fraction and the directional distribution of the fiber in the composite. The macro‐cell is further decomposed into simpler elements whose stiffness is determined from tow geometry and the stiffness of the fiber/matrix constituents. The macroscopic stiffness of the textile composite is obtained from the macro‐cell definition using an Effective Response Comparison (ERC) technique. Numerical examples are presented illustrating the developed methodology. Experimental characterization of several textile composites and the correlation of the experimental data with model predictions are considered in a companion paper.