Study On Properties Of Carbon Fiber Weft Inlay Knitted Fabric Composites

In this study,i have learned the mechanical properties of weft knitted composites in recent years,such as tensile,bending,compression,energy absorption and other properties of the development background.There are many kinds of high-performance fibers used in weft-knitted composites,among which carbon fibers which with low density,high specific strength,high specific stiffness and anti-fatigue are the first choice to prepare high-performance composites.At present,carbon fiber composites are mainly used in aerospace,transportation,energy and sports goods and other fields.However,due to the brittleness of carbon fibers,when it to knittde fabrics,the phenomenon of fiber damage is serious,so it is necessary to further explore the knitting properties and material properties of carbon fiber.In the experiment,i have tested the tensile properties,nodule properties and damage strength of carbon fibers on the sansi UTM5105 electronic universal testing machine.Subsequently,the knitted properties of carbon fiber were analyzed through test results.The results showed that the tensile strength of the carbon fiber was 6 times that of the nodule strength.It shows the strength damage of carbon fiber is serious,and the tensile strength damage rate of the fiber is 67%,after knitted.It is indicated that carbon fiber is not suitable for knitting into loops under normal conditions.Therefore,in the process of this subject,the fabric parameters and knitting parameters of computerized flat knitting machine should be adjusted to minimize the damage of carbon fiber fabric.In the experiments,six weft-knitted inlay fabrics with different parameters were knitted by adjusting feeding tension,drawing force,yarn bending depth and machine speed.The reinforcement and epoxy resin matrix were compounded by moulding process,so Eight kinds of composites with different interlining density,different bending depth and different number of layers were prepared.The transverse,oblique and longitudinal tensile and bending properties of the material were tested on the sansi UTM5105 electronic universal testing machine,and analyzedthe test results which under the different parameters.The results show that weft-inserting yarn in weft-knitted inglay structure can effectively improve the transverse tensile properties of materials,and the higher the yarn density,the better the transverse properties of materials.The insertion of inlay yarn decreases the density of loops in the longitudinaldirection,and decreases the longitudinal performance,but little.The yarn bending depth affects the stitch length.The stitch length is longer,the longitudinal and oblique strength of the material is stronger,and the transverse strength is smaller.When the number of lay up layers is increased,the tensile properties of the composites are enhanced.The bending test results show that the higher the yarn density is,the greater the transverse stress is.The longer the fabric loops,the greater the fabric ductility,and the greater the longitudinal bending stress,but the more the number of fabric layers,lend to the brittleness of the material greater.In summary,the performance of carbon fiber weft knitted composites is different in three directions.