Three-dimensional hybrid structural composites

The mechanical behavior of 2D and 3D reinforced fabric composites is analyzed and a novel 3D fabric structure is studied both experimentally and theoretically.; Mechanical properties of woven fabric reinforced glass/graphite-epoxy hybrid composite materials were evaluated. The effect of production parameters on impact and stress-strain behavior was investigated. ANOVA analysis was performed to find the influence of each parameter on the mechanical properties and the relations between parameters. Thickness of the composite and hybrid combination had effect on stress-strain and impact properties. Clamp pressure had significant effect on stress properties. Failure mechanisms of the laminates were evaluated. Obvious delamination zones were observed with some samples. Regression models for defined variables and mechanical properties were developed.; The effect of stacking sequence on mechanical properties of stitched composites is studied for low velocity impact damage. Tests were performed for the same volume fraction (V_f) with different hybrid sequence and ply angle. The incorporation of glass fibers in carbon reinforced structures improved impact properties and increased the strain to failure. The addition of carbon fibers to the surface of glass-reinforced composites increases the flexural modulus for undamaged samples. Tensile failure mechanism of damaged plies seems to be affected by the interaction of reinforcement property, hybrid order and ply angle.; The 3D hybrid weaving/knitting machine is a combination of knitting and weaving elements. A novel fabric structure and its mechanics were introduced to the literature in the study. The novel structure consists of multilayers of warp and ±45° bias yarns. Final fabric structure can be accepted as a modified through-the-thickness interlock type 3D fabric where the role of weft yarns in fabric formation is undertaken by oppositely laid bias yarns. The structure of the loops in the novel fabric is not the same as it is in the traditional textiles. Thus, this new type of loop is named ‘3D loop’ which consists of two arms of laid-in section in Z-axis and a needle loop in XY plane.; Knitting has been widely used in forming 3D fabric structures for more than three decades by stitching technique. However no efforts has been directed to the mechanics of 3D loop in the structure. The geometry of the novel fabric with special emphasis on 3D loop has been evaluated. Young's modulus of the fabric is deduced from the initial load-extension behavior. The theoretical models are compared with experimental results and reasonable agreement has been reached. The tensile modulus and strength of the 3D hybrid fabric composite was compared with multiaxial warp-knit fabric composites.