2D 编织 C/SiC 孔边致密化结构多尺度混合模型与拉伸性能

A modelling method is proposed to characterise the densification structure of the hole edges of 2D braided C/SiC composites during Chemical Vapour Infiltration（CVI）. A Representative Volumetric Element（RVE）model，taking into account the random distribution of holes，is developed to calculate the equivalent elastic modulus of 2D braided C/SiC composites. On this basis，a macro-meso hybrid model of 2D braided C/SiC composites with a densified structure of the hole edge is developed. Based on the 3D hashin failure criterion and the modified Von Mises failure criterion，the progressive damage model of the 2D braided C/SiC composite is developed，and its uniaxial tensile stress-strain behaviour is simulated. The validity of the model is verified by comparison and analysis with experimental data. The tensile strength of the open-hole 2D braided C/SiC composites is calculated for different porosities，radii of the dense zone and hole diameters，and the effects are analysed. The results show that with the increase of porosity，the material stiffness and tensile strength decreased，when the porosity increased from 5% to 20%，the tensile strength decreased by 26. 05%；with the increase of radius of dense zone，the material stiffness decreased more slowly and the failure strength increased，when the radius of dense zone increased from 0 mm to 0. 75 mm，the tensile strength increased by 14. 17%；with the increase of hole diameter，the hole edge stress concentration effect is enhanced，the degree of damage to the hole edge increased，the faster the material damage，when the hole diameter increases from 0. 5 mm to 2 mm，the tensile strength decreased by 35. 01%.