Study Of C/C Woven Composite Mechanical Properties

Carbon/Carbon(C/C)composites are regarded as the most promising heat-resistant materials for long-playing structures at ultra-high temperature and have important strategic value to the national defense.However,researches on mechanical properties such as stiffness and strength of C/C composites are behindhand,because of their complex internal structure.In order to improving the application efficiency of C/C woven composites,it is necessary to research their mechanical properties.In this paper,the stiffness properties,strength properties and perforated C/C woven composites test specimen are studied by finite element method based on mesoscopic mechanics,which can reduce development risk,cost and cycle.The main work done in this dissertation includes the following:(1)The stiffness properties of the 3D orthogonal C/C woven composites and 8-harness satin woven composites are studied.Stiffness properties of 3D orthogonal C/C woven composites are predicted using unit cell which is built according to the material mesoscopic structure and compared with experimental values of a reference.Stiffness properties of C/C 8-harness satin woven composites are predicted with unit cell and generalized method of cells.(2)The strength properties of the 3D orthogonal C/C woven composite are studied and compared with values of a reference.In this paper,fiber failure adopts maximum stress criterion and matrix failure adopts a new criterion.The failure criterion of matrix considers that compressive stress will prevent shear damage on the fracture surface.The tensile,compression,shear strength of unit cell are predicted and the failure modes in different loads are simulated by using ABAQUS with user-defined subroutines materials(UMAT).(3)The finite element model of perforated C/C woven composites test specimen is built and its mechanical responses under tensile and compression loads are simulated.The meshes around the openhole are built according to the detail of the structure.The results show that the damage of 3D orthogonal C/C woven composites under tensile and compression load appears in the shape of “X”.The ultimate load,strength value and the damage evolution process are provided.