Forti Tiago, Batistela Gustavo, Forti Nadia, Vianna Nicolas
Simworx R & D, Campinas 13087-727, Brazil.
Exact Sciences, Environmental and Technologies Center, Pontifical Catholic University of Campinas (PUC-Campinas), Campinas 13086-099, Brazil.
Materials (Basel). 2020 Oct 15;13(20):4585. doi: 10.3390/ma13204585.
Concrete exhibits a complex mechanical behavior, especially when approaching failure. Its behavior is governed by the interaction of the heterogeneous structures of the material at the first level of observation below the homogeneous continuum, i.e., at the mesoscale. Concrete is assumed to be a three-phase composite of coarse aggregates, mortar, and the interfacial transitional zone (ITZ) between them. Finite element modeling on a mesoscale requires appropriate meshes that discretize the three concrete components. As the weakest link in concrete, ITZ plays an important role. However, meshing ITZ is a challenging issue, due to its very reduced thickness. Representing ITZ with solid elements of such reduced size would produce very expensive finite element meshes. An alternative is to represent ITZ as zero-thickness interface elements. This work adopts interface elements for ITZ. Damage plasticity model is adopted to describe the softening behavior of mortar in compression, while cohesive fractures describe the cracking process. Numerical experiments are presented. First example deals with the estimation of concrete Young's modulus. Experimental tests were performed to support the numerical test. A second experiment simulates a uniaxial compression test and last experiment simulates a uniaxial tensile test, where results are compared to data from the literature.
混凝土呈现出复杂的力学行为，尤其是在接近破坏时。其行为在均匀连续体以下的第一级观测尺度，即细观尺度上，受材料非均匀结构相互作用的支配。混凝土被假定为粗骨料、砂浆以及它们之间的界面过渡区（ITZ）的三相复合材料。细观尺度上的有限元建模需要合适的网格来离散混凝土的这三个组分。作为混凝土中最薄弱的环节，ITZ起着重要作用。然而，对ITZ进行网格划分是一个具有挑战性的问题，因为其厚度非常小。用如此小尺寸的实体单元来表示ITZ会产生非常昂贵的有限元网格。一种替代方法是将ITZ表示为零厚度的界面单元。这项工作采用界面单元来表示ITZ。采用损伤塑性模型来描述砂浆在压缩时的软化行为，而粘结断裂则描述开裂过程。给出了数值试验。第一个例子涉及混凝土杨氏模量的估计。进行了试验测试以支持数值试验。第二个试验模拟单轴压缩试验，最后一个试验模拟单轴拉伸试验，并将结果与文献数据进行比较。
