钢纤维混凝土细观层次数值模拟研究
发布时间：2018-07-13 09:50
【摘要】：钢纤维混凝土（SFRC）是一种复杂的非均质复合材料，宏观力学模型将其视作均质材料来研究其力学性能，并通过一系列试验得出参数以指导工程实践，从某种程度而言，均质的简化很难描述钢纤维混凝土材料在外荷载下裂纹形成、发展及连通的损伤破坏过程。本文将从细观层次上将钢纤维增强混凝土(SFRC)材料看作是由钢纤维增强体、混凝土基体所组成的非均质两相复合材料，对其力学性能进行数值模拟，模拟时暂不考虑二者的界面粘结性能。 抗拉强度和抗压强度是钢纤维混凝土材料的基本力学性能指标，是研究复杂应力状态的基础。混凝土是典型的多相复合材料，掺入钢纤维之后，强度提高程度不大，但其力学性能得到改善。和混凝土材料相比，脆性显著改善，应力应变曲线有较缓的下降段，不会出现典型的脆性破坏。本文结合MATLAB数学计算软件产生伪随机数的功能与ABAQUS有限元分析软件的非线性计算功能，建立不同体积含量的钢纤维随机分布于代表体积单元(Representative Volume Element，RVE)的三维数值模型，将钢纤维看作桁架（truss）单元嵌入基体中，不考虑二者的界面粘结。采用均匀化方法，，首先通过与文献中试验进行对比，调试部分参数，计算由随机分散的钢纤维、混凝土基体两相复合材料的抗压应力应变曲线和抗拉应力应变曲线，以验证细观数值模拟的可行性和准确性，然后进行参数化分析，考虑随机钢纤维的长径比、体积含量变化对复合材料力学行为的影响。 针对钢纤维和混凝土基体之间的界面粘结性能，出于计算时间和计算精度的考虑，分别建立混凝土基体、钢纤维以及二者粘结层的二维平面应变有限元模型，运用基于断裂力学的内聚力模型，合理设置参数，首先与文献中单根钢纤维拉拔试验进行对比，验证采用该模型的正确性，进而考虑钢纤维类型、嵌入基体的长度变化对界面粘结性能的影响。
[Abstract]:Steel fiber reinforced concrete (SFRC) is a kind of complex heterogeneous composite material, which is considered as homogeneous material by macroscopic mechanical model to study its mechanical properties, and parameters are obtained through a series of tests to guide engineering practice. Homogenization is difficult to describe the damage and failure process of steel fiber reinforced concrete (SFRC) under external loading. In this paper, the steel fiber reinforced concrete (SFRC) material is regarded as a heterogeneous two-phase composite composed of steel fiber reinforcement and concrete matrix at the mesoscopic level, and its mechanical properties are numerically simulated. The interfacial bond properties of the two are not considered in the simulation. Tensile strength and compressive strength are the basic mechanical properties of steel fiber reinforced concrete (SFRC) and are the basis of studying complex stress state. Concrete is a typical multiphase composite material. After adding steel fiber, the strength of concrete is improved little, but its mechanical properties are improved. Compared with the concrete material, the brittleness is obviously improved, the stress-strain curve has a slow descending section, and there is no typical brittle failure. Combined with the function of generating pseudorandom numbers by MATLAB and the nonlinear calculation of Abaqus finite element analysis software, a three-dimensional numerical model of steel fibers with different volume contents distributed randomly to Representative Volume element (RVE) is established in this paper. The steel fiber is regarded as a truss (truss) element embedded in the matrix without considering the interface bond between them. By using homogenization method, the compressive stress-strain curves and tensile stress-strain curves of randomly dispersed steel fiber and concrete matrix two-phase composites are calculated by comparing with the experiments in literature and adjusting some parameters. In order to verify the feasibility and accuracy of mesoscopic numerical simulation, parameterized analysis was carried out to consider the influence of the aspect ratio and volume content of random steel fiber on the mechanical behavior of composites. According to the interfacial bond behavior between steel fiber and concrete matrix, a two-dimensional plane strain finite element model of concrete matrix, steel fiber and bond layer is established for the consideration of calculation time and accuracy. The cohesive force model based on fracture mechanics is used to reasonably set the parameters. Firstly, compared with the single steel fiber drawing test in literature, the correctness of the model is verified, and the type of steel fiber is considered. The influence of the length of the embedded matrix on the interfacial adhesion.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528.572
本文编号：2118962
[Abstract]:Steel fiber reinforced concrete (SFRC) is a kind of complex heterogeneous composite material, which is considered as homogeneous material by macroscopic mechanical model to study its mechanical properties, and parameters are obtained through a series of tests to guide engineering practice. Homogenization is difficult to describe the damage and failure process of steel fiber reinforced concrete (SFRC) under external loading. In this paper, the steel fiber reinforced concrete (SFRC) material is regarded as a heterogeneous two-phase composite composed of steel fiber reinforcement and concrete matrix at the mesoscopic level, and its mechanical properties are numerically simulated. The interfacial bond properties of the two are not considered in the simulation. Tensile strength and compressive strength are the basic mechanical properties of steel fiber reinforced concrete (SFRC) and are the basis of studying complex stress state. Concrete is a typical multiphase composite material. After adding steel fiber, the strength of concrete is improved little, but its mechanical properties are improved. Compared with the concrete material, the brittleness is obviously improved, the stress-strain curve has a slow descending section, and there is no typical brittle failure. Combined with the function of generating pseudorandom numbers by MATLAB and the nonlinear calculation of Abaqus finite element analysis software, a three-dimensional numerical model of steel fibers with different volume contents distributed randomly to Representative Volume element (RVE) is established in this paper. The steel fiber is regarded as a truss (truss) element embedded in the matrix without considering the interface bond between them. By using homogenization method, the compressive stress-strain curves and tensile stress-strain curves of randomly dispersed steel fiber and concrete matrix two-phase composites are calculated by comparing with the experiments in literature and adjusting some parameters. In order to verify the feasibility and accuracy of mesoscopic numerical simulation, parameterized analysis was carried out to consider the influence of the aspect ratio and volume content of random steel fiber on the mechanical behavior of composites. According to the interfacial bond behavior between steel fiber and concrete matrix, a two-dimensional plane strain finite element model of concrete matrix, steel fiber and bond layer is established for the consideration of calculation time and accuracy. The cohesive force model based on fracture mechanics is used to reasonably set the parameters. Firstly, compared with the single steel fiber drawing test in literature, the correctness of the model is verified, and the type of steel fiber is considered. The influence of the length of the embedded matrix on the interfacial adhesion.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528.572
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