含孔隙的2.5D编织陶瓷基复合材料弹性常数预测

Prediction of Elastic Constants of 2.5D Braided Ceramic Matrix Composites with Porosity

为获取更为全面的编织陶瓷基复合材料弹性常数,支撑材料力学性能研究,提出考虑纤维性能退化和基体孔隙的编织陶瓷基复合材料弹性常数预测方法。围绕2.5D编织陶瓷基复合材料,通过微焦点断层扫描获取材料孔隙率和孔隙分布,并测量碳化硅纤维单丝经热处理后的高温强度和模量。再结合细观力学有限元法理论,通过Digimat建立含孔隙的2.5D陶瓷基复合材料代表体单元有限元模型,计算得到材料弹性常数。同时对元件级试验件进行了室温单向拉伸和面内剪切试验,弹性常数计算值和试验值吻合较好,验证了该方法可以用来预测含孔隙的2.5D编织陶瓷基复合材料的弹性常数,为其力学性能与失效机理分析建立基础。

In order to obtain more comprehensive elastic constants of braided ceramic matrix composites and to study the mechanical properties of materials,a method for predicting elastic constants of braided ceramic matrix composites considering fiber degradation and matrix porosity is proposed.Based on 2.5D braided ceramic matrix composites,the porosity and pore distribution of SiC fiber were obtained by Micro-CT scanning,and the high temperature strength and modulus of SiC fiber single wire after heat treatment were measured.Combined with theory of finite-element method in mesoscopic mechanics,a finite element model of 2.5D ceramic matrix composites with porosity was established by Digimat,and the elastic constants of the materials were calculated.At the same time,the unidirectional tensile test and in-plane shear test were carried out at room temperature,and the calculated values of elastic constants were in good agreement with the test values,which proves that the method can be used to predict the elastic constants of 2.5D braided ceramic matrix composites with porosity.The basis for the analysis of mechanical properties and failure mechanism of the composite is established.