Progressive Damage Analysis And Experimental Study Of 2D Woven Composites

Self-lubricating spherical plain bearings with woven composites liners is one of the important components on aerospace and aviation aircraft,and their structure reliability plays a vital role in overall safety of the aircraft.Bearing performance and reliability,mainly affected by the properties of the woven composites of the lubricating layer,especially the mechanical properties of the woven composites.The woven form of the woven composites and the interaction and properties of the component materials determine the resistance to damage of the application.Through physical tests can verify and evaluate the mechanical properties of specific structures and components under specific conditions,but the mesoscopic changes and damage processes of the components are not clearly kNown.Therefore,based on meso-structural model,component material properties and interaction relationships,this paper mainly adopts the numerical analysis methods to study the damage mechanism of woven composites.Specific research work as follows:The experimental analysis of the basic mechanical properties of twill weave composites was performed based on the national standard of tensile and compression tests for fiber reinforced plastics.The out-of-plane compression method of thin-layer fiber material was proposed according to the fiber-reinforced in-plane compression method.The damage mode,elastic modulus and fracture strength of the twill weave composites were obtained through the experiments.Physical tests provide basic data for model validation of numerical analysis and theoretical analysis of progressive damage.Based on the stiffness and strength characteristics of Kevlar49,PTFE fiber and resin matrix,Through calculation,the stiffness and strength of aramid fiber bundle and PTFE fiber bundle in different directions were obtained,which are provides basic parameters for calculating the mechanical properties of composite structures.The research on material damage theory,computational mathematical model and technical method of composite structure was performed.The damage factors representing different damage modes were brought into the constitutive equations of the fiber bundle and matrix,and the damage constitutive equation of the corresponding componentmaterial was obtained.With the exponential damage evolution model and the three-dimensional Hashin initial failure criterion introduced,a progressive damage UMAT user subroutine containing three component materials was compiled and the established damage mathematical model was verified by the laminated composites.The establishment of damage mathematical model lays a foundation for numerical simulation analysis.Based on damage theory,mathematical model and composite structure modeling,numerical analysis of woven composites progressive damage was carried out.The approximate buckling shape and cross-sectional shape of the fiber bundle were obtained by the microsection experiment,which was then compared with the existing fiber bundle model hypothesis.Accordingly,the biconvex-lens section was selected for parametric modeling.Combined damage mathematical model,the progressive damage of the plane twill weaving composite under the axial tension and out-of-plane compression was analyzed by the finite element method.The damage state and damage propagation mode and its law of the component materials under different loading conditions are obtained.The numerical analysis results were compared with the physical test results to verify the validity of the finite element method.The proposed out-of-plane compression test method and the micro progressive damage analysis model not only provide a reference for the further research on woven composites,but provides theoretical and technical support for the manufacture of high performance woven composites,especially woven composite self-lubricating liners.