Filament-level Modeling Of 3-D Orthogonal Woven Textile Fabrics And Tensile Micromechanics Analysis

The three-dimensional woven composites which have the excellent mechanical properties such as high specific stiffness,high specific strength,impact resistance and fatigue resistance have been developed rapidly in many fields,such as aerospace,military,biology and so on.As the reinforcement of composite materials,the basic mechanical properties of 3D woven fabrics directly affect the mechanical properties of composite materials.At present,the research on the mechanical properties of 3D woven fabrics at home and abroad has gradually changed from the traditional high-cost experimental test and low-efficiency mathematical modeling theory analysis to the digital simulation method with low cost and high controllability.In this paper,three-dimensional orthogonal woven fabric is taken as the research object,and its weaving process is simulated in the time domain,and its micro-geometric structure model is established at the approximate fiber scale.On this basis,its tensile properties are analyzed by ABAQUS.This method not only reduces the experimental cost,but also improves the scope of research.The main research content and research results of this topic are as follows:(1)This paper proposed a method of calculating the inter-fiber friction based on the Digital Element Approach(DEA).Then,based on this,the micro-geometry model of five three-dimensional orthogonal woven fabrics were built at sub-yarn scale with varied cross-sectional yarn shape via weaving process simulation.Each model is composed of 4,7,12,19,and 37 digital fibers per yarn respectively.Through the experimental comparison,it is concluded that when the number of fiber per yarn equals to 19,the micro-geometry of the numerical model is the most consistent with the microscopic picture of the actual fabric.(2)Based on the research results in Chapter 2,a three-dimensional orthogonal fabric equal-scale model and unit cell model composed of three-layer warp yarns and four-layer weft yarns are established by the Digital Element Approach,and then imported to the ABAQUS/CAE pre-processing to establish the finite element models of the two models.The tensile process and results of the two models are analyzed respectively and compared with the results of the tensile experiment in the literature.It is concluded: both the threedimensional orthogonal fabric unit cells model and the three-dimensional orthogonal fabric proportional model are capable of using ABAQUS for tensile mechanical performance analysis.Between them,the equal proportion model can analyze the tensile deformation of the three-dimensional orthogonal fabric from a macro perspective,while the unit cell model can reflect the tensile deformation of fabric from the micro perspective,with a faster calculation time.(3)On the basis of the Chapter 3,the influence of fabric parameters on its tensile mechanical properties is studied by using the finite element method.The results show that the peak value of stress-strain curve increases with the increase of fiber density,modulus and friction coefficient.When Poisson's ratio increases from 0.1 to 0.25,there is no significant change in the slope of the stress-strain curve and no difference in the peak value of the curve.