Study On The Mechanical Properties Of Glass-Fiber Warp-Knittied Fabric Reinforced Composites

Knitted-fabric-reinforced composite is one type of textile fabrics reinforced composites, whose reinforcement is knitted fabrics. In a knitted fabric, the fibers or yarns form loops that can glide over each other and deform easily. This makes the knitted fabric formable by comparison with other fabrics like woven or braided fabrics. The modulus of high performance fibers is great and is not easy to bend, so more attention is put on the multi-axial warp-knitted fabrics. Multi-axial warp-knitted fabrics contain basic loops and inserted yarns. The inserted yarns play the chief roles on properties of reinforced composites while basic warp loops ensure the stability of the inserted yarns together, which strictly can not be called warp-knitted fabric. So we have knitted some different pieces of warp-knitted fabrics with glass-fiberyarns, solidified them with unsaturated polyester resin and made tensile and flexural experiments for the reinforced composites.In this paper, we have knitted nine pieces of warp-knitted fabrics with glass-fiber yarns. We initially have studied and discussed on the knitting behavior of glass-fiber yarns, the design of the warp-knitted fabrics' structures and the process parameters. Based on the two-dimensional loop structure, we analyzed and calculated the bear segments of the loops in order to explain the mechanical properties of the reinforced composites.In this paper, we have introduced the sorts of resins, the solidified compound of unsaturated polyester resin and the operation of hand lay-up method, and have studied the process to control quality of the composites. In the composites, glass-fiber yarns exist by loops of three-dimensional structure, so it is easy for resin to immerge the fabrics and got lower porosity. In the meantime, fiber content of warp-knitted fabric is low and difficult to control the quality too.In this paper, we have consulted test method for tensile and flexural mechanical properties of glass fiber-reinforced plastics and have made some tensile and flexural experiments in lengthways and transverse orientation with these composites. From the test, we have got the parameters on mechanical properties of composites-strength and modulus. According to analyzing comparing the experimental data and the geometry structures of these fabrics, we have tried to find the roles that the fabric structure played on tensile and flexural mechanical properties of warp knitted fabric reinforced composites. As a result, we find that the more segments and the lower bending of the loops on loading orientation, the better strength and modulus of the reinforced composites.