13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- The damage evolution of 2D-Woven-C/SiC composite under tension loading Min-ge Duan1,2, Fei Xu1,*, Zhong-bin Tang1 1 School of Aeronautics, Northwestern Polytechnical University, Xi’an, 710072, China 2 State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China * Corresponding author: fay.xu@nwpu.edu.cn Abstract A meso-numerical model is set up to investigate the damage evolution of 2D woven C/SiC based on RVE(representative volume element) because the woven composite has a periodic in-plane structure. Periodic boundary conditions are imposed to the model. Three material models for the fibers, the matrix, and the yarn/matrix interface are considered. Basic damage modes and their evolutions are observed in the simulation. Firstly, the matrix is damaged at the global applied stress around 50Mpa, which agrees well with the tests. The stress/strain relation obtained from the meso-numerical model can represent the behavior of the 2D woven C/SiC under tension loading. Secondly, the void in the matrix plays an important role. The bundle/matrix interface is essential to investigate the interface debonding. Keywords 2D-C/SiC composites, RVE, damage mechanisms 1. Introduction C/SiC, as one of the most promising high temperature structural materials for its performance, such as low coefficient of thermal expansion, excellent thermal shock resistance, abrasion resistance, and high specific strength/modulus, has been applied in structures such as air-breathing engines, hot-gas valves and aerospace thermal structures. Consequently, the mechanical properties of the C/SiC has been an active research field for several decades. Both experimental studies and macro- or micromechanical methods have been used to obtain the mechanical properties of the C/SiC[1-13,20]. In experimental studies, the mechanical characterization of the C/SiC were studied by classical strain measurements, ultrasonic method, AE(acoustic emission) technique , infrared thermography and microstructural observations under the load of uniaxial tension[1-6], compression[1,5], in-plane shear[7], tension fatigue[8,9], thermal fatigue[10,11] and low-velocity impact[12]. Based on the expensive experiments, the damage modes found by microstructural observations are: matrix cracking, transverse bundle cracking, bundle/matrix and inter-bundle debonding, fiber cracking, ply delamination, bundle splitting and matrix wear. The damage evolution or development mention in the former studies are all deduced from the possible damage modes, which can only reflect the overall damage event and the detailed mechanical behavior of the constituents identification is beyond the detection. Fortunately, it is possible to identify detailed mechanical behavior of the constituents in FEM. However, there is not so much study on C/SiC with simulation method as experiment method. The prediction of the stiffness tensor has been carried out with FEM[13]. While, little work was done on the prediction of damage evolution and the strength[4]. Recently, simulation of plain woven fabrics based on photomicrograph measurement and idealized sinusoidal representation of the weave structure has been successfully applied to determine their mechanical properties by taking the advantages of their inherent periodicity of woven fabric architecture[14-19] at mesoscale in-plane. Both elastic moduli [14,15], damage[16] and fracture[18] behavior of the woven fabrics have been successfully predicted for the case of two-phase heterogeneous materials without considering the fiber-matrix interface using FEM by RVE (representative volume elements). While, it has been confirmed that interface obviously has great
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