A Multi-scale Finite Element Model And Elastic Testing For Ceramic Matrix Composites

Ceramic matrix composite(CMCs) material with high elastic modulus, low density and elevated working temperature, made it widely applied to aerospace engineering. Thus, scholars at home and abroad have developed many methods to study its mechanical behavior, which include macro mechanics method, micro mechanics method and multi-scale method. The macro mechanics method has small calculation, the micro mechanics method predicting accurate. Combined the advantages of macro mechanics method and micro mechanics method, the multi-scale method got more attention in recent years. Scholars have built many multi-scale models to predicting the elastic properties of CMCs, but the results are not satisfying for these models were based on ideal structure of materials. So, how to build a reasonable and reliable model of CMCs is required.In this monograph, we developed a new XCT FEM method to build a multi-scale model based on X-ray computed tomography, C++ programming and FEM analysis. In XCT FEM method, we built the element based on the pixel point in XCT slices, and constructed the finite element model and predicted the elastic modulus of CMCs. This method has the following advantages:(1) Based on the program CMCsXCT and XCT slices with color marking, we can build finite element model automatically.(2) The finite element model is similar to the real structure of CMCs, and the predicted results are accurate.(3) Different from other model based on real structure, in XCT FEM method, we developed the window method, average volume method and the XCTFEM method based on compressed slices to optimize the XCTFEM method, made the model element number is much smaller than the traditional model.And we also conducted some experiments to CMCs.(1) we did X-ray computed tomography test and obtained the XCT slices of CMCs.(2) We got the elastic modulus of matrix without removing the components surrounding around through Nano-indentation test.(3) We did micro measurement for fiber bundle, and obtained the volume ratio of its components.(4) We also did the tensile and shear tests, obtained the stress-strain curve and experimental modulus, the results showed good correlation between experimental results.