摘要
复合共晶体的断裂是开始于危险点的微观损伤的累积结果。其损伤特征与复合共晶体内纤维的分布形式有关。基于损伤余自由能表达式,定义纵向、横向和剪切三个损伤变量;根据含同向平行纤维复合共晶体的微观结构特性,确定损伤变量表达式,并计算损伤柔度张量。基于损伤柔度张量和复合共晶体的局部应力场,分析损伤应变场的分布规律并确定最大损伤应变;依据最大线应变理论,定义加载函数,建立含同向平行纤维复合共晶体的损伤强度模型。依据无损共晶基复合材料的强度预报公式,确定共晶体损伤时复相陶瓷的宏观断裂强度,并分析宏观断裂强度的尺度效应。结果表明,复合陶瓷的断裂强度随共晶体损伤程度的增加而降低,并且损伤变量越大,断裂强度的尺度效应范围越小。
The fracture of composite eutectic is accumulated by micro-damage started from dangerous point. The damage feature is connected with distribution of fibers in composite eutectic. The longitudinal, transverse and shear damage variables are defined by the damage complementary free energy. Based on the microstructure characteristics of composite eutectic with parallel fibers, the expressions of damage variables is determined and damage flexibility tensor is calculated. Considering such tensor and the local stress field of composite eutectic, the damage strain field of composite eutectic is obtained and the maximum damage strain is determined. On account of the maximum strain theory, the loading function is defined, and the micro-damage strength model of composite eutectic with parallel fibers is built. According to the fracatre strength expression of composite ceramic with no damage eutectic, the fracture strength of composite ceramic with damage eutectics is gotten. The size dependence of the fracture strength is analyzed. The result showed that as the numerical value of damage variables increases, the fracture strength of composite ceramics may lessens, and the size dependence range of the fracture strength may smaller.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2014年第2期98-103,共6页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(11272355)
关键词
复合共晶体
损伤变量
损伤柔度张量
损伤应变场
最大线应变理论
损伤强度模型
composite eutectic
damage variable
damage flexibility tensor
damage strain field
maximum strain theory
damage strength model
