A multiscale analysis for predicting the elastic properties of 3D woven composites containing void defects

Void defects, which can significantly affect the elastic properties of materials, are inevitable in 3D woven composite materials. In this study, experiments are conducted to obtain parts of the elastic moduli of 3D woven composites and thereby verify the applicability of the following finite element models. Analytical equations considering void effect are also proposed to predict the elastic moduli of fiber tows. Multiscale FE models are developed, and periodical boundary conditions are applied to the representative volume element models to obtain all nine elastic moduli. The effects of void defect on the elastic properties of fiber tows and woven composites are discussed. Results indicate that void defects exert significant influence on the elastic moduli of fiber tows, except on the out-of-plane elastic modulus. The elastic moduli of 3D woven composites are more sensitive to the voids in fiber tows than those in the matrix of woven composites.