考虑孔隙的三维编织陶瓷基复合材料弹性常数预测方法

提出了利用气孔单元并考虑基体孔隙随机分布来预测三维编织陶瓷基复合材料弹性常数的方法.通过工业computed tomography(CT)扫描技术测得孔隙率,在胞元模型中利用Monte-Carlo仿真技术在基体上随机投入气孔单元来模拟三维编织陶瓷基复合材料中的孔隙,利用胞元有限元模型计算了孔隙率对三维编织陶瓷基复合材料弹性常数的影响规律.结果表明:1孔隙率对三维编织陶瓷基复合材料弹性常数具有明显的影响;2对给定的孔隙率,孔隙的位置分布对沿纤维束方向弹性模量的影响较小;3随着孔隙率增加,沿纤维束方向弹性模量降低.同时,开展了SiC/SiC复合材料的室温拉伸试验,弹性模量计算值和试验结果吻合较好,表明该方法可以用来预测含孔隙的三维编织陶瓷基复合材料的弹性常数.

Prediction method of elastic constants of 3-D braided ceramic matrix composites considering pores

A method for predicting elastic constants of 3-D braided ceramic matrix composites was established by means of pore elements and taking into account its random distribution. The porosity was measured by industrial computed tomography (CT) scan systems. The Monte-Carlo technique was utilized to simulate the stochastic distribution of the pores in the 3-D braided ceramic matrix of the unit cell model. The effect laws of porosity on elastic constants of 3-D braided ceramic matrix composites were obtained through the finite element model of the unit cell. The results indicate that: (1) there exists obvious influence of porosity on the elastic constants of 3-D braided ceramic matrix composites; (2) for a certain porosity, the location distribution of pores has almost no effect on the elastic modulus along fiber bundle orientation; (3) the elastic modulus along fiber bundle orientation decreases with the increasing porosity. The tension test of SiC/SiC composites was also conducted at ambient temperature. The predicted value of elastic modulus matches with the measured data. The result has validated the proposed methodology for predicting the elastic constants of 3-D braided ceramic matrix composites with pores.