为了研究混凝土在轴向应力作用下的微裂纹萌生扩展过程和位移场、应力场的变化,采用有限-离散元法(Combined finite-discrete element method, FDEM)进行混凝土数值模型重构,生成了结构上含多边形随机骨料、砂浆和界面过渡区三相物质的...为了研究混凝土在轴向应力作用下的微裂纹萌生扩展过程和位移场、应力场的变化,采用有限-离散元法(Combined finite-discrete element method, FDEM)进行混凝土数值模型重构,生成了结构上含多边形随机骨料、砂浆和界面过渡区三相物质的数值模型。主要结论如下:(1)有限-离散元法可以很好地模拟混凝土在外部轴向荷载下开裂的全过程,包括微裂纹萌生、扩展、贯通等过程。(2)由骨料、砂浆和两者之间的界面过渡区造成的力学参数非均质性和混凝土内部结构的非均质性共同造成了混凝土位移场和应力场分布的不均匀性。且界面过渡区由于力学参数较为薄弱,最易萌生微裂纹,首先产生破坏。(3)非均质性会影响混凝土的局部应力场分布,造成应力集中现象。(4)FDEM能够较好地模拟高性能混凝土的拉压比(0.064),为更进一步模拟大尺度混凝土建筑物的工程特性打下良好的基础。展开更多
Rock,concrete and other geo-materials,due to the presence of microstructural inhomogeneity,their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the mate...Rock,concrete and other geo-materials,due to the presence of microstructural inhomogeneity,their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the materials.In this study,by introducing a cohesive zone model based on fracture mechanics into the framework of deformable discrete element method,a continuous-discontinuous coupling analysis approach for simulating the fracture of quasi-brittle materials is proposed.The cohesive interface elements are inserted into certain engineering or research region.It is assumed that damage and fracture occur only in the interface elements,while bulk material is modeled to be elastic.The Mohr-Coulomb criterion with tension cut-off is adopted as the damage initiation criterion,and a scalar damage variable representing damage in the material is used to describe the rate at which the material stiffness is degraded.Cracks are simulated explicitly by the failure of the interface elements.Numerical simulations are performed in order to validate the suggested method.Partial applications are also listed.The results show that this method provides a simple but effective tool for the simulation of crack initiation and propagation,and it can reflect the whole process of quasi-brittle materials from small deformation to large deformation and failure.展开更多
文摘为了研究混凝土在轴向应力作用下的微裂纹萌生扩展过程和位移场、应力场的变化,采用有限-离散元法(Combined finite-discrete element method, FDEM)进行混凝土数值模型重构,生成了结构上含多边形随机骨料、砂浆和界面过渡区三相物质的数值模型。主要结论如下:(1)有限-离散元法可以很好地模拟混凝土在外部轴向荷载下开裂的全过程,包括微裂纹萌生、扩展、贯通等过程。(2)由骨料、砂浆和两者之间的界面过渡区造成的力学参数非均质性和混凝土内部结构的非均质性共同造成了混凝土位移场和应力场分布的不均匀性。且界面过渡区由于力学参数较为薄弱,最易萌生微裂纹,首先产生破坏。(3)非均质性会影响混凝土的局部应力场分布,造成应力集中现象。(4)FDEM能够较好地模拟高性能混凝土的拉压比(0.064),为更进一步模拟大尺度混凝土建筑物的工程特性打下良好的基础。
基金supported by the National Basic Research Program of China(973 Program)(Grant No.2013CB035901)the National Natural Science Foundation of China(Grant No.51379161)+2 种基金the Program for New Century Excellent Talents in University(Grant No.NCET-10-0657)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120141110008)the Fundamental Research Funds for the Central Universities(Grant No.2012206020207)
文摘Rock,concrete and other geo-materials,due to the presence of microstructural inhomogeneity,their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the materials.In this study,by introducing a cohesive zone model based on fracture mechanics into the framework of deformable discrete element method,a continuous-discontinuous coupling analysis approach for simulating the fracture of quasi-brittle materials is proposed.The cohesive interface elements are inserted into certain engineering or research region.It is assumed that damage and fracture occur only in the interface elements,while bulk material is modeled to be elastic.The Mohr-Coulomb criterion with tension cut-off is adopted as the damage initiation criterion,and a scalar damage variable representing damage in the material is used to describe the rate at which the material stiffness is degraded.Cracks are simulated explicitly by the failure of the interface elements.Numerical simulations are performed in order to validate the suggested method.Partial applications are also listed.The results show that this method provides a simple but effective tool for the simulation of crack initiation and propagation,and it can reflect the whole process of quasi-brittle materials from small deformation to large deformation and failure.
