SiC/SiC mini复合材料拉伸性能分散性的数值仿真方法

建立了一种能够高效计算连续纤维增强SiC/SiC陶瓷基复合材料力学性能统计分布函数的数值仿真方法。建立SiC/SiC mini复合材料简化二维胞元模型,输入组分材料力学性能参数的概率分布函数,得到胞元的力学性能。将胞元作为mini复合材料二维模型的单元对模型进行网格划分,并赋予其材料性能参数,从而得到mini复合材料的拉伸应力-应变曲线。经多次重复计算得到了mini复合材料拉伸应力-应变曲线的概率分布函数。从结果中发现,SiC/SiC mini复合材料拉伸强度满足威布尔分布,且相比于纤维和基体强度的模数,复合材料拉伸强度的模数增大,即分散性减小,同时尺度参数降低,表明mini复合材料出现概率最大的拉伸强度值变小;随着纤维和基体强度概率分布威布尔模数的增大,mini复合材料拉伸强度的尺度参数有增大的趋势。 

Numerical simulation method of the variability in tensile properties of SiC/SiC minicomposites

An efficient numerical simulation method for calculating the statistical distribution function of mechanical properties of continuous fiber reinforced SiC/SiC ceramic matrix composites was established. The parameters of the probability distribution function of the constituents were assigned into a two-dimensional model of the representative unit cell and the corresponding mechanical properties of the unit cell were achieved. Afterwards, the attributes and material property parameters of the representative unit cell were homogenized into a two-dimensional model of minicomposites and macroscopic tensile stress-strain response of the minicomposites could be obtained. By conducting hundreds of computations in minicomposites with stochastic mechanical parameters in constituents, the probabilistic stress-strain curves were derived. It was found that the strength of SiC/SiC minicomposites satisfied the Weibull distribution well. In comparison with individual constituents as fibers and matrix, the Weibull modulus of the strength in the macroscopic minicomposites was much larger, indicating the decrease of the scatter in the strength. On the contrary, the scale parameter in the minicomposites was smaller than that of both constituents, implying the reduction of the strength with the highest probability density. Furthermore, with the increasing Weibull modulus of the strength in either fibers or matrix, the scale parameter of minicomposites strength increased simultaneously.