Preparation And Properties Of Carbon Fiber Weft Knitted Fabric Reinforced Composites

Fiber reinforced composites have been studied for decades.Because of their high plasticity,the knitted fabrics can be directly made into all kinds of complicated shape of composites such as tubular,cone,etc,and have achieved high speed development.Knitted fabrics are divided into weft knitted fabrics and warp knitted fabrics.As reinforcement of composites,the weft knitted fabrics possess excellent performance in the flexibility and extensibility.The carbon fiber has high axial strength and modulus,low density.Carbon fiber weft knitted fabric reinforced composites have advantages over other fiber composites.Fiber bending degree is larger in the process of knitting weft knitted fabric.Yarn damage greatly reduces the mechanical properties of the composites.It is necessary to study knitting ability of carbon fiber weft knitted fabric,to reduce the damage in the process.Through researching structures and mechanical properties of carbon fiber weft knitted fabric composites,the aim is to analysis the influencing factors,establish a theoretical model,and provide theoretical support for its applications.This topic analyzed knittability of carbon fiber yarn,and the properties of carbon fiber were compared with the cotton and polyester.As a result,the tensile strength of carbon fiber was high,but the hook and circle strength of carbon fiber were lower than the cotton and polyester.The nine different stitches of weft knitted fabrics were knitted on manual and computerized flat knitting machines with carbon fiber yarns.The yarn tension,drawing force,loop length and machine speed were adjusted and optimized.With epoxy resin as matrix,the laminates of carbon fiber weft knitted fabric reinforced composites were produced by manual molding technology.The tensile and bending properties of nine kinds of composites were tested and analyzed on vertical and horizontal directions.The results show that the tensile and bending properties of composite specimens have relationship with their fabric structure,yarn orientation,the number of yarns bearing load and fiber volume fraction and other factors.The model of the 1 × 1 modified jersey fabric composites were built by Pro/E software.The longitudinal tensile properties were analyzed and calculated with ABAQUS finite element analysis software.Through the simulation,analysis and calculation,the results had good consistency with tensile testing results.