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Establishment of mesoscopic stochastic models of concrete in three dimensions based on Python-Abaqus

DOI：10.7511/jslx20210412001

 作者 单位 吴宇航 湘潭大学 土木工程与力学学院, 湘潭 411105 肖映雄 湘潭大学 土木工程与力学学院, 湘潭 411105 徐亚飞 湘潭大学 土木工程与力学学院, 湘潭 411105

混凝土在细观层次上是由粗骨料、砂浆及两者间过渡区(界面层)组成的三相复合材料,建立一个能反映实际骨料级配、含量及形态的随机骨料模型是进行混凝土细观力学数值模拟的前提。本文通过编写Python脚本实现了Abaqus的二次开发,获得了含球形、椭球形(卵石)及凹凸型多面体(碎石)骨料并考虑了界面层的三维混凝土细观随机模型。结果表明,在三级配下可投放球形骨料的体分比可超过55%,对椭球和多面体骨料形状的模拟也较为真实。同时,提出了一种可提高骨料体积含量的布尔切割入侵判别法,并成功地对椭球骨料和多面体骨料进行了投放试验。由于程序已将粗骨料、砂浆和界面层自动分离,在进行网格剖分时可避免复杂的单元属性判别,得到的网格剖分满足粗骨料、砂浆及界面层网格协调性要求。最后,利用建立的几何模型进行了单轴压缩静力学数值模拟,进一步验证了混凝土细观随机模型的可靠性。

The mesoscopic stochastic models of concrete treat it as a three-phase composite material which consists of coarse aggregates,mortar and interfacial transition zones (ITZs).An appropriate random aggregate model by considering the actual gradation,content and shape of aggregates is the basis of numerical simulation of mesomechanical behaviors of concrete.In this paper,the secondary development of ABAQUS is realized by writing Python script in order to obtain three-dimensional mesoscopic stochastic models of concrete which contain spherical aggregates,ellipsoidal aggregates (gravels) and concave-convex polyhedron aggregates (crushed stones) with ITZs,respectively.The corresponding results have shown that the volume fraction of spherical aggregates can exceed 55% in cases of different gradations and the resulting ellipsoidal aggregates and polyhedral aggregates are also basically same as the shape of the actual aggregates.At the same time,a so-called intrusion detection method by Boole cutting is proposed,which can obviously improve content of aggregates.The corresponding packing tests are successfully performed for ellipsoid aggregates and polyhedral aggregates by using this method.Since the coarse aggregates,mortar and ITZs are automatically separated in the resulting program,the complex element attribute discrimination can be avoided in mesh generation.The resulting meshes can well meet the conforming requirements among coarse aggregates,mortar and ITZs.Finally,numerical simulation of uniaxial static compression is performed by using the resulting geometric models and the reliability of mesoscopic stochastic models of concrete is further verified.