Study On Mechanical Properties Of Glass Fiber Weft Knitted Fabric Reinforced Composites

With their unique three-dimensional bending loop structures and the connection mode of adjacent loops, weft knitted fabrics has good extensibility and flexibility. Weft knitted fabrics as reinforcement possess excellent ductility, impact resistance and formability of composite materials. Compared with other textile structural composites, the research on weft knitted fabric reinforced composites is reported less and the studies are mainly about the uniaxial, biaxial knitted fabrics and multi-axial warp-knitted fabrics formed by high-performance yarn. The loops of these knitted fabrics are not interlocked by high strength yarns. Therefore, researching the mechanical properties of the weft knitted fabric composites knitted by high performance fiber has a certain significance.This paper first analyzed the knitted performances of glass fiber yarns, and made a comparison with cotton yarn and polyester filament. The experimental results showed that the tensile strength of glass fiber yarns was relatively high, the their coefficient of friction was larger. The their hook tensile strength and circle strong efficiency were far lower than cotton and polyester filament, and the strength damages of glass fiber yarns after knitting are more serious. So the research shows that it is difficult that glass fiber yarns were knitted weaving on the knitting machine. In the knitting process, the seven different stitches of weft knitted fabrics which have better quality and smooth surface were knitted through adjusting and optimizing the computer flat knitting machine speed, yarn tension, take-away force, loop length and other parameters.Secondly, preparation of composites used a vacuum assisted resin transfer molding method, and the basic parameters of the composite specimen were tested. Results show that laminates of composites possessed smooth surface, lower porosity and higher fiber volume content. The mechanical properties such as tensile and bending of the composite samples were tested on a universal testing machine, and the reasons of the differences in different directions of mechanical performance parameters were analyzed, and the influence of perform structure on the mechanical properties of composite was discussed. Testing results show the sizes of mechanical properties are mainly affected not only by the number of bearing yarn, the yarn of orientation degree, but also by the proportion of fiber content.Finally, using Pro/E software established a space model of 1+1 modified plain knitted fabric reinforced composites, and the tensile properties of 1+1 modified plain weft knitted composites were analyzed by finite element analysis and calculated with ABAQUS finite element analysis software. The experimental results show the results had little difference between analysis and calculation through simulation and the measurement in tensile test.