陶瓷基复合材料多层界面相应力传递的有限元模拟

Finite element simulation of stress transfer through the multilayer interphase in ceramic matrix composites

针对陶瓷基复合材料(CMCs)多层界面相的应力传递进行了有限元模拟。采用圆柱单胞模型描述CMCs的细观结构,按相应界面相亚层的实际厚度建立明确的界面相,并假设界面相亚层之间及界面相与纤维、基体之间初始完好结合,然后赋予各界面相亚层不同的材料参数,并采用轴对称有限元法进行求解,最终建立了多层界面应力传递的模拟方法。分别对比了不同厚度热解碳(PyC)界面相、PyC和SiC两种不同成分界面相及(PyC/SiC)和(SiC/PyC)两种结构界面相的应力传递模拟结果。从剪应力沿纤维方向分布及径向分布特点可以看出,通过合理配置CMCs内部多层界面相的结构、成分和厚度,可以实现界面相应力传递及失效模式的控制和优化。

The stress transfer through the multilayer interphase in ceramic matrix composites was simulated by finite element method.The microstructure of ceramic matrix composites(CMCs)was modeled by a cylinder unit-cell,the sub-layers of interphase were created according to their real thickness within the model.The interfaces between interphase sub-layers,interphase and fibers,interphase and matrix were all assumed to be bonded perfectly.Different material properties were defined for interphase sub-layers,and the axis-symmetry finite element method was applied to analysis the stress.After all,a simulation method for stress transfer through the multilayer interphase was developed.The simulation results for stress transfer within pyolytic carbon(PyC)interphase of different thickness,interphase of different constituents(PyC and SiC),and interphase of different structure((PyC/SiC)and(SiC/PyC))were compared.It can be seen from the distribution of stress along fiber and radial direction that the stress transfer and failure mode of interphase in CMCs can be controlled and optimized by rational allocation of the structure,constituent and thickness of multilayer interphase.