Composites with 3-D stitched fabrics

The use of Fiber Reinforced Polymer (FRP) composites in the construction industry has been growing rapidly because they are more durable and economical over conventional materials. Currently, almost all composite products are manufactured with 1-D fibers (unidirectional) or 2-D fabrics (bidirectional), typically leading to ply-by-ply failure (due to shear-lag phenomena) or premature failure of matrix and fibers leading to the interface failure. The present paper reports on the effects of through-thickness reinforcement on the mechanical properties in the 3-D stitched fabrics. In this study, composites were fabricated using 3-D stitched fabrics with different (1) fiber architecture, (2) stitch density, (3) stitch material and (4) manufacturing process. Strength and stiffness of composites with 3-D stitched fabrics (at coupon level) under tension, bending and shear loads were experimentally established. Structural properties of composites made of 3-D stitched fabrics were compared with those composites made of unidirectional fibers and 2-D stitched fabrics. Composites made of 3-D stitched fabrics were found to have enhanced bending and tensile strength and stiffness by 30–40%;.