An Integrated Approach for Characterizing Non-Crimp Fabric Composites with Interlaminar Stitching Reinforcement

Resin-infused non-crimp fabric (NCF) composites have emerged as attractive alternatives to traditional autoclave pre-impregnated composites allowing for lower production costs, better handling, and improved shelf life while maintaining excellent in-plane mechanical properties compared to other types of textile composites. NCF composites can be further reinforced in the out-of-plane (interlaminar) direction by stitching high tensile strength yarn through the thickness of the laminate preform prior to resin infusion to improve resistance to delamination. Stitch-reinforced NCF materials are inherently multiscale materials with a complex internal structure. As a result, the development of efficient constitutive models able to accurately capture deformation and failure mechanisms for implantation in a virtual design platform is a main challenge that delays an increased use of NCF composites. This work has for objectives to contribute to such development. In particular, an integrated approach that uses high fidelity Digital Image Correlation (DIC) and in-situ X-Ray Computed Tomography (CT) measurements combined with data-driven Finite Element (FE) modeling is presented for characterizing stitch-reinforced NCF composites. The modeling approach uses an embedded element approach for discrete representation of the stitching reinforcement and is implemented in commercial FEM software Abaqus. Input data and predictive capabilities of the numerical model are verified for progression of mode I delamination failure in double-cantilever beam (DCB) NCF specimens with interlaminar stitching reinforcement.