Multi-scale modeling and strength prediction of plain woven SiC/SiC composites
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摘要: 连续SiC纤维增强SiC基体复合材料(SiC/SiC)具有优异的高温力学性能、辐照稳定性及较低的氚渗透率,在核工程结构领域具有良好的应用前景,掌握其承载状态下的损伤演化和强度性能,对SiC/SiC复合材料的应用具有重要指导意义。本文基于平纹编织SiC/SiC复合材料的制备过程和组分材料分布的多尺度特性,考虑复合材料微观结构的局部近似周期性,建立了纤维丝尺度和纤维束尺度单胞模型。使用有限元分析软件对纤维丝尺度模型的弹性性能和强度性能进行预测,将这些性能参数代入纤维束尺度模型,引入Tsai-Wu失效准则,根据材料的不同失效模式并对失效单元进行方向性刚度折减,模拟了平纹编织SiC/SiC复合材料在单轴拉伸载荷下的渐进损伤过程。数值模拟曲线与试验曲线吻合较好,实现了对平纹编织SiC/SiC复合材料强度的有效预测。
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关键词:
- 平纹编织SiC/SiC复合材料 /
- 多尺度建模 /
- 周期性边界条件 /
- 渐进损伤 /
- 强度
Abstract: Continuous SiC fiber reinforced SiC matrix composites (SiC/SiC) have good application prospects in the nuclear engineering structures, due to their excellent high-temperature mechanical properties, irradiation stability and low helium permeability. Understanding the damage evolution mechanism and the strength is significant for the application of SiC/SiC composites. Based on the multi-scale characteristics of the fabrication process and component material distribution of plain woven SiC/SiC composites, fiber-scale (the fiber yarn model) and yarn-scale (the woven fabric model) unit cell models were established considering the local periodicity of the microstructure of the composites. In this paper, finite element method was applied to predict the elastic properties and strength properties of the fiber-scale model, which were then substituted into the yarn-scale model. The Tsai-Wu failure criterion was employed and the stiffness reduction was conducted in the failed elements according to the different failure modes. The progressive damage process of plain woven SiC/SiC composites under uniaxial tensile load was simulated. The numerical simulation curve is in good agreement with the experimental curve, which demonstrates the predictive capability of the proposed method for predicting the strength of plain woven SiC/SiC composites.
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