Mechanical Properties Of Carbon Fiber Weft Knitted Fabric Reinforced Composites Laminates

In this study,the mechanical properties,acoustic emission testings of deformation damage and low velocity iMPact properties of Carbon fiber weft knittied fabric reinforced composites were studied.Toray T300 1K Carbon fiber filament woven 1×1 variable plain stitch,interlock,inter-ply and intral-ply hybrid weft knitted structure of two kinds of weave structures were used to fabricate CFWK fabric and epoxy resin matrix reinforced composites by lamination process.The tensile,bending and low-velocity iMPact properties of CFWK reinforced composites were studied.AE test was used to evaluate the three failure modes of composites in the first two experiments: matrix cracking,fiber debonding and fiber fracture.Analying the effects of ply number,ply angle and fabric structure on the properties of CFWK reinforced composites.It is proved by experiment that the mechanical properties show an upward trend with the increase of layers and thickness.The tensile strength and bending strength of 1×1 variable plain stitch reinforced composites are the best in the two-layer structure,which are 206.22 MPa and 213.43 MPa respectively.At the same time,the tensile fracture strength of [0/90] laying is 35%-50%lower than that of [0/0].AE signal frequency cluster analysis showed that fiber debonding was the main failure mode among the three failure modes,and accounted for more than 60%of the total debonding when stretching and curving along the longitudinal direction of the two-layer structure weft knitted composite.Under the iMPact energy of 4J,the maximum load of CFWK reinforced composites with three-layer of interlock structure increases by275% co MPared with that of single-layer structure.Perforation failure of three-layer interlock CFWK reinforced composites under iMPact energy of 10 J.