Abstract: In this work, the mechanical behavior of partially sintered ceramics under both tensile and compressive loadings was investigated by performing 3D discrete element method (DEM) simulations. The simulation results indicated that the failure of samples under tensile loading was dictated by the nucleation of crack, whereas for compressive loading it was linked to the coalescence of cracks. By monitoring the time sequence of bond breakage and its failure mode, it was found that for tensile loading the dominate failure mode of bond was tensile fracture, whereas for compressive loading it was shear fracture. The fracture strength of sample was closely related to the critical tensile (?c,t) and shear (?c,s) fracture strengths of bond. As to the partially sintered alumina ceramics considered in this work, it was found that the predicted tensile and compressive fracture strengths can both be in quantitative agreement with experimental data. The simulation results indicated that the influence of the distribution of bond strength on the compressive fracture strength of sample was minor. While for tensile fracture strength, it depended on the type of distribution: for Gaussian distribution, the strength of sample only weakly depends on the distribution width, whereas for uniform distribution, the strength of sample decreases notably with the increase of distribution width.

Key words: partially sintered ceramic material, Al2O3, tensile loading, compression loading, fracture strength, discrete element method

摘要： 通过开展三维离散单元法数值模拟，考察了部分烧结陶瓷在单轴拉伸和压缩加载条件下的力学响应行为。模拟结果表明，拉伸加载下试样的破坏表现为裂纹“成核”效应，而压缩加载下则呈现为裂纹“聚并”效应；通过追踪固体键的断裂顺序和断裂模式发现，拉伸加载下固体键的破坏主要源于拉伸作用，而压缩加载下则为剪切作用。试样的宏观断裂强度与固体键临界拉伸强度?c,t和临界剪切强度?c,s有关。对于考察的部分烧结Al2O3陶瓷材料，?c,t=?c,s下模拟得到的试样拉伸强度和压缩强度能与实验数据定量吻合。压缩加载下，固体键断裂强度的分布形式和分布宽度对试样断裂强度的影响较小；拉伸加载下，试样断裂强度取决于固体键的分布形式：高斯分布时，试样断裂强度基本不受分布宽度的影响；均匀分布时，试样断裂强度随分布宽度的增大而减小。

关键词: 部分烧结陶瓷材料, Al2O3, 拉伸加载, 压缩加载, 断裂强度, 离散单元法