Preparation And Properties Of Planar Triaxial Carbon Fiber Mesh Materials

Triaxial Woven Fabric（TWF）is interwoven by two sets of warp yarns and one set of weft yarn at a certain angle（0°,±60°）with uniform hexagonal holes.The in-plane load is distributed evenly,and the areal density of the material is reduced effectively,which helps to manufacture lightweight structure.TWF composite is widely used in aerospace field especially the antenna reflector.This paper studied carbon fiber TWF materials comprehensively,included the meso-structure analysis,the weaving process to make uniform and stable structure,the resin transfer process for epoxy matrix composite.Tensile properties in different directions were tested.It mainly included the following contents:（1）The cross section microscopic morphology of the carbon fiber triaxial woven fabric（CFTWF）was observed by microcomputer tomography technology（Micro-CT）.The buckling shape of the yarn in the fabric was obtained.Combined with yarn interweave pattern,the meso-structure unit cell model of CFTWF was constructed.Based on the geometric relationship of the unit cell model,the geometric relationship equations of yarn porosity,fabric surface density and fabric thickness were derived.（2）The study discovers that the CFTWF structure is distributed with hexagonal holes and triangular holes regularly during actual service.Triangular holes are an influencing factor in the meso-analysis of triaxial fabrics.The coefficient n of the triangle hole side length a₂ and the yarn width c is introduced,and the relationship equation between the coefficient n and the fabric porosityνis established.When the coefficient n is 0,The triangular holes are eliminated,and the fabric porosityνis 0.33.With the increase of the coefficient n,the pore area of the triangle area increases,and the fabric porosityνincreases.（3）According to the interweave pattern of TWF,a set of simple weaving tooling was designed.Different fabric structural parameters with carbon fiber specifications 1k,3 k,6 k,and the yarn center distances 3 mm,4.5 mm,5.5 mm and 6 mm were manufactured.Using epoxy resin film as the matrix,the TWF composite was prepared by vacuum-assisted molding technology.（4）The tensile properties of CFTWF materials at 7 angles of 0°,5°,10°,15°,20°,25°and 30°are studied.The apparent failure situation and the tensile fracture curve are observed,the tensile fracture mechanism is analyzed,and the tensile load angle is 0°-180°,the contour diagram of the tensile fracture strength and tensile modulus of the TWF material is drawn.The range of tensile strength is 32.5 MPa,and the range of tensile modulus is 16.33 MPa.（5）Based on the material tensile failure analysis,the non-contact method is used to measure the full-field strain of the specimens at different angles during the tensile process.The study found that the tensile failure modes of the 0°and 5°specimens are mixed tensile and shear failure modes,while the 10°,15°,20°,25°and 30°specimens are pure shear failure modes.The interwoven structure of the triaxial fabric affects the distribution law of the strain cloud picture.