Abstract: The reinforcement of polymer matrix composites by through-the-thickness stitching is a promising technique for raising the damage tolerance of laminar structures. In this paper, a three-dimensional finite element micromechanical modeling approach is proposed for predicting the macro-elasticity constants of stitched/RTM CFRP composites. In the model, the actual shape of stitching yarn and the position between yarns and laminate are taken into account. The unit cell of the model is picked up from entire thickness of stitched laminate. Each lamina is taken as a body but not a panel and the elastic constants are calculated in three directions. As fewer hypotheses are taken, the analysis result is more precise. Comparing the relevant predictions with the experimental results validates the model presented in this paper. The comparison shows that there is good agreement for the elastic properties and it can be used in the engineering design.

Key words: stitched composites, elastic properties, micromechanical analysis, 3D finite element, experimental confirmation