基于棒状共晶体边界滑移的复相陶瓷开裂应力

根据共晶基复相陶瓷的组织结构特征，建立开裂应力预报模型，为分析复合材料的破坏形式提供了理论依据。共晶基复相陶瓷以含纳/微米纤维的棒状共晶体为基体，并在棒状共晶体周围分布有少量的片晶和球晶。基于棒状共晶体内纤维-基体间强约束界面所传递的拉应力，建立了载荷传递模型；根据两棒状共晶体之间或共晶体与周围其他晶粒之间的弱界面特性，通过边界滑移条件确定棒状共晶体表面切应力；考虑棒状共晶体方位的随机性，当复相陶瓷承受拉伸载荷时，借助棒状共晶体的外加应变与复相陶瓷外加载荷间的关系，得到复相陶瓷开裂应力的理论表达式，结果表明开裂应力与棒状共晶体内纳/微米纤维的直径和体积分数密切相关，复相陶瓷开裂应力随着纤维直径的增大而增大，随纤维体积分数的增大而减小。

Cracking Stress of Composite Ceramic Based on the Boundary Slip of Rod-shaped Eutectics

According to the organizatinal structure characteristics of eutectic composite ceramics, a prediction model of cracking stress is established, which provides theoretical foundation for analyzing the damage form of composite materials. The matrix of eutectic composite ceramics is mainly composed of rod-shaped eutectics with nano/micron fibers. A small amount of lamellar crystals and spherulites are distributed around the rod-shaped eutectics. Baesd on tensile stress transmitted by strong constraining interphase between fibers and matrix in the rod-shaped eutectics, a load-transmitting model is set up. On the basis of weak constraining interphase characteristics between rod-shaped eutectics or between rod-shaped and crystal particles around the rod-shaped eutectics, the shear stress on the surface of the rod-shaped eutectics is obtained by boundary slip conditions. Considering the random orientation of the rod-shaped eutectics, a theoretical expression of composite ceramic cracking stress is gotten based on the relationship between the applied strain of rod-shaped eutectics and the applied load of composite ceramics as the composite ceramics are subjected to tensile load. The results indicate that cracking stress is closely related to the diameter and volume fraction of nano/micron fiber. The cracking stress increases with the increase in fibers diameter and decreases with the increase in fibers volume fraction.