Research On Microstructure And Mechanical Properties Of Variable Cross-section Annular 3D Woven Composites

Variable Cross-Section annular 3D woven composite is a new composite material which developed on the basis of three-dimensional woven composite materials, which is produced by the traditional weaving techniques and equipment to expand the system, and it has good design ability and strong profiling capability. Variable Cross-Section annular 3D woven composite has good structural integrity and stability of the overall performance because of weaving method with increasing warp. The paper studied on the mechanical properties of a typical composite structure through three aspects of theoretical model, numerical simulation, experiments, and got some useful conclusions.Based on the variable circular cross-section of composite material of adding yarn and oval cross-section assumption fiber bundles, a new three-dimensional structure of woven geometric model of micro round table was established. The paper made a detailed study on the volume fraction change of three dimensional woven composites of truncated cone along the height and thickness caused by section changing and adding yarn, on this basis to determine varying-yarn zone of 3D woven composites of truncated cone micro structure, using the volume averaging method to predict the elastic constants of adding yarn district area and the non-plus unit.The paper used ABAQUS software to analyze mechanical properties of three-dimensional woven composite from parts to the whole, and used the finite-element method to predict the elastic constants of adding yarn district area and the non-plus unit. The paper achieved the unit body stiffness reduction through the user material subroutine, and got the simulation in the damage evolution under compression load. Lastly, it established a whole finite element model of three-dimensional woven, and did the stress and deformation analysis under compression load.This paper studied the three-dimensional woven round table forming process under the RTM equipment, and used the PAM-RTM software to simulate the resin injection process, verified the rationality, feasibility of RTM mold and molding process. The three dimensional woven round the axial compression test has done, by the comparison between experimental and theoretical predicted values, it showed the correctness of mechanical model.