Research On Matrix Failure And Mechanical Performance Of The Ceramic Matrix Composites With Pores

Ceramic matrix composites have been demonstrated as a great engineering practical future in the defensible field of aeronautics and astronautics for its excellent performance. It is inevitable that pores are included in the composites, and matrix failure is one of the important failure models, so it is important to research the matrix failure and mechanical performance of ceramic matrix composites with pores.Mechanical performance of porous material was researched by differential method, three-phase model and lattice model. The results have been compared with each other. Lattice model was used to consider the effects of random distribution of pores, size and shape. Research shows that random distribution makes some decentralization on the mechanical performance; pore's size makes little effect on the efficient mechanical performance; trend of simulative results of the hexahedron pore is the same with the tetrahedron pore. The relation curve between the mechanical performance and porous density has been simulated, which agree well with the experiential results.By combining the three-dimensional lattice model with statistics method, failure of porous ceramic materials was researched. The stress-strain curve of the failure process was simulated; the effects of the pore's random distribution, size and shape on the failure strength was analyzed. Research shows that the failure process of porous ceramic shows some plastic; random distribution makes some decentralization on the failure strength; the smaller of the pore's size, the smaller of the failure strength, and the trend becomes smaller gradually; trend of simulative results of the hexahedron pore is the same with the tetrahedron pore. The relation curve between the failure strength and the pore density was simulated, which agrees well with the experiential results.The shortage of the primary Monte Carlo method for modeling matrix cracking was analyzed. By considering the effects of the pore density and the interface de-bonding energy, the improvement method was carried out from three different aspects, which were respectively based on the critical strain energy release rate criterion, maximum shear stress criterion and the fracture mechanical method. The improved model considered the effects more roundly, agreed well with the experiment data.