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.