Eutectic fracture model and damage localization band of composite ceramics with reinforced lamellae

Abstract

The two-scale cell model is constructed based on the microstructure of composite ceramics with reinforced lamellae eutectic. The cohesive bond fracture stress between the matrix and reinforced phase is obtained considering the conditions of the rupture of the cohesive bond. The microcosmic damage fracture stress is obtained through introducing the damage variables and the cohesive bond fracture stress. The analytic results agree well with the experimental ones. According the Dugdale-Barenblatt model and regarding the microcosmic damage fracture stress of eutectic as residual intensity, the damage localization band model at crack tip is built. Quantitative analysis show that when the damage variable is high, the length of the damage localization band increases with the volume fraction of the reinforced lamellae increasing. The increases volume fraction of the lamellae leads to the declining residual intensity and the break of the strong binding force of the interphase. Reducing the material damage and selecting suitable volume fraction of reinforced lamellae phase can increase the fracture stress of eutectic and reduce the length of damage zone. So that the threshold of crack propagation and enhance the material strength would become high.