3D Fabrics for Composite Bridges

For flat sheets, the usual ways of making fibre reinforced plastics (FRP) are random short fibre placements, which have the disadvantage of discontinuities at fibre ends, and multi‐ layer laminates of filament prepregs or 2D textile fabrics. For 3D shell structures, filament winding, press‐forming and fabric draping are used. Integral 3D fabrics are an attractive alternative. They can be made in a variety of ways, but those most relevant to FRP bridges are woven fabrics consisting of (1) thick multilayers linked by threads in the Z‐direction either flat or (2) made in more complicated 3D shapes, (3) hollow multilayer fabrics containing voids. Braids may also be used.The advantages of 3D woven fabrics for composites are:- Resistance to delamination and improved through‐thickness properties- Ease of handling for assembly of components for impregnation and autoclaving orfor thermal bonding- Manufacture on commercial weaving machines with limited modification- Economy of production, especially if large volumes are needed- Competitive with steel, particularly if glass or polyester yarns are used forreinforcement.The paper will describe the structures that are available, design procedures and manufacturing methods. The results of a case study for a small footbridge composed of three parts, the travel surface made from floor beams, stringers and the deck, and two side‐ structures serving as girders. The loading capacity of the bridge comes from the strengths of the floor beams, stringers and the girders.