预测平纹编织C/SiC复合材料等效导热系数的三维纤维随机模型

提出了一种能够刻画平纹编织C/SiC复合材料编织结构的三维纤维随机模型，探讨了微观结构影响宏观等效导热系数的机理。采用蒙特卡罗法模拟纤维位置的随机分布，用有限元法计算等效导热系数，通过数理统计方法分析在不同纤维体积分数下等效导热系数的随机分布规律；并且比较了相同纤维体积分数下，纤维随机模型平均等效导热系数与纤维周期排列模型等效导热系数的差别。结果表明:在不同体积分数下，纤维位置随机等效导热系数都呈高斯分布；纤维随机模型中纤维会出现聚集现象，形成局部“导热热障”，所以纤维随机模型平均等效导热系数小于纤维周期排列模型，这种差异在中等纤维体积分数下最明显。 

Three-dimensional fiber random model to predict effective thermal conductivity of plain braided C/SiC composites

A random microstructure cell model was developed to predict the effective thermal conductivity of plain braided C/SiC composites material, so as to describe the real distribution of fibers and the braiding-structure. Then, the influence mechanism of microstructures on macroscopic effective thermal conductivity was discussed. The random distribution of fibers was simulated by Monte Carlo method, and the effective thermal conductivity was calculated based on finite element method, and the results were presented in statistical forms. It was shown that, the Gaussian distribution function described the distribution of effective thermal conductivity accurately. For a random fiber distribution, fibers segregated in a microscopic level; Portions of the fibers came into contact and formed some local “heat flow obstacles”, which led to a smaller effective thermal conductivity than that of the general cell model.