Research On In-Plane Quasi-Static Tensile And Shear Properties Of Three-Dimensional Carbon Fiber Woven Composites

As an advanced composite material,3D woven composite materials have excellent mechanical properties and are widely used in various engineering fields.Compared with the lamination process,the three-dimensional weaving process improves the integrity of the composite material.The spatially distributed threedimensional fiber bundle skeleton structure greatly enhances the material’s out-ofplane mechanical properties and damage resistance in all directions.At the same time,the complex structure of woven composite materials has brought great challenges to its mechanical properties.This paper takes carbon fiber reinforced epoxy resin-based three-dimensional woven composites as the research object.First,the experimental and simulation studies on the mechanical properties of the in-plane shear load are carried out,and then the weft direction tensile mechanical properties of the material are developed.In the simulation study,a simulation method for simulating the tensile and shear failure of three-dimensional woven composites is given.The first chapter introduces the purpose and significance of this paper.Focus on the investigation of domestic and foreign literature,summarize the test methods and simulation theories of domestic and foreign scholars on the research of threedimensional woven composite materials,including shear experiments,shear fixture design,finite element modeling,damage failure criteria,damage evolution model and research on shear nonlinear theory.The second chapter carried out the in-plane shear experimental research and corresponding finite element modeling of 3D woven composite materials.A threedimensional woven composite material in-plane quasi-static shear experiment was designed and carried out,and the stress-strain curve,shear stiffness,shear strength and offset shear strength of the shear experiment were obtained.By taking a photomicrograph of the surface of the test piece after the experiment,the damage mechanism of the shear test piece was analyzed.By measuring the surface geometry of the test piece,a three-dimensional woven composite material unit cell model was established.The third chapter carried out a simulation study on the tensile mechanical properties of 3D woven composites.The Linde criterion is applied to the threedimensional situation to simulate the tensile failure behavior,and the tensile mechanical properties of the three-dimensional woven composite material in this paper are predicted.By comparing with the experimental results in the literature,the reliability of the tensile simulation method given in this paper is verified.Chapter 4 simulates the in-plane quasi-static shear properties of 3D woven composites.By adopting the improved Hashin criterion to consider the factors of shear nonlinearity,and introducing the shear nonlinear constitutive relationship given by Hahn and Cai to simulate the shear nonlinear behavior of fiber bundles.By writing the ABAQUS subroutine,the nonlinear shear damage factor stress calculation and shear behavior simulation of the fiber bundle are realized,and it is extended to the shear modulus reduction and large strain of the matrix.For the matrix,the maximum shear stress criterion is used as the damage criterion,and the exponential damage evolution law is used.By simulating the shear behavior of woven composite unit cells,the stress-strain curve of in-plane shear was obtained and compared with the experimental results.