Micromechanical Strength Modeling and Investigation of Stitch Density Effects on 3D Orthogonal Composites

Abstract

A 3D orthogonal woven S2-glass composite is investigated using finite element micromechanics to characterize the stiffness and the strength. The methods are applied to a targeted parametric investigation of the effects of stitch density on strength properties and potential benefits of through-thickness reinforcement, such as resistance to transverse shear and delamination, with some consequent loss of in-plane properties. Direct modeling of the exact microstructure from scanning electron microscope visualization provides a precise knowledge of the mechanics and the failure modes of the microstructure under various loading conditions. Modeling results are verified by comparison to experimental data. In-plane stiffness and strength are predicted with 90% or better accuracy. Transverse shear stiffness was less well predicted, but strength was still predicted within 86% accuracy.