Abstract
It is of great significance to study the damage and fracture mechanism of trigonometrically symmetric eutectic multiphase ceramics with excellent mechanical properties at room temperature and high temperature. According to the microstructure characteristics of inner triangular symmetric eutectic in multiphase ceramics, a two-scale cell model containing triangular symmetric eutectic was established. The fracture stress of cohesive bond in eutectic was calculated by considering the conditions of cohesive bond fracture at interface phase and fiber junction. The damage variable was introduced and combined with cohesive bond fracture stress to establish the microcosmic damage fracture stress model of eutectic Based on the Dugdale Barenblatt model, the damage localization band model is established by introducing the micro damage fracture stress as the residual strength. It is found that with the increase of fiber volume fraction, the strong confinement of interface phase is destroyed, the residual strength decreases and the length of damage localization band increases with the increase of fiber volume fraction. Reducing the damage degree and selecting the appropriate fiber volume content can increase the fracture stress of eutectic, and then reduce the length of damage localization band, increase the threshold value of crack instability propagation, and enhance the material strength.
Highlights
Eutectic composite ceramics have excellent mechanical properties such as high temperature resistance, high strength, high hardness and corrosion resistance, which has very important application value in the field of ceramic armor and aerospace
According to the microstructure of the composite ceramics, considering the effect of micro damage on the effective properties of the composite ceramics, a two-scale cellular model is established to analyze the cohesive bond fracture conditions, and the micro damage fracture stress model is established the length of localized band of end damage was predicted
It can be seen from the above formula that the cohesive bond fracture stress of triangular symmetric eutectic is related to the elastic modulus, surface energy of fiber reinforced phase and matrix in the eutectic body, and the bonding bond arrangement mode shared by the eutectic two phases
Summary
Eutectic composite ceramics have excellent mechanical properties such as high temperature resistance, high strength, high hardness and corrosion resistance, which has very important application value in the field of ceramic armor and aerospace. Based on the microstructure characteristics of eutectic ceramics containing parallel fibers, a damage fracture model of parallel fiber eutectic composite ceramics was established [10]. Zhou Fenghua and Wang Lili [15] used the linear cohesive fracture model to describe the expansion behavior of the virtual fracture point These models study the bond fracture of single-phase materials, and for composite ceramics with eutectic properties, it is necessary to improve these models. According to the microstructure of the composite ceramics, considering the effect of micro damage on the effective properties of the composite ceramics, a two-scale cellular model is established to analyze the cohesive bond fracture conditions, and the micro damage fracture stress model is established the length of localized band of end damage was predicted
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