基于降阶均匀化理论的混凝土双尺度力学性能分析

混凝土材料细观特性对宏观力学性能有着重要影响。为进一步分析混凝土细观特性对宏观力学行为的影响规律,将混凝土材料简化为由骨料、砂浆和界面三相组成,编制了随机凸多面体骨料生成、投放和网格剖分算法,建立可用于有限元计算的满足级配要求的随机细观模型。针对直接使用细观力学模型计算量较大的问题,采用降阶均匀化理论,对混凝土细观胞元模型进行预处理并编制了相应的双尺度计算程序。对不同强度混凝土进行了单轴静态压缩双尺度计算,与实验数据和细观力学模拟结果符合较好。研究表明,降阶均匀化理论在加快求解速度的同时具有较高的精度,可以用于混凝土的多尺度力学性能分析。

Two scale study on mechanical properties of concrete based on the reduced order homogenization theory

Mesoscale characteristics of concrete have considerable influence on its macroscale mechanical properties.In this paper,a random aggregate model,which followed the probability distribution of real structure,was established and used in FEM analysis to investigate relationship between the mesoscale characteristics and macroscale mechanical properties.Concrete was considered as a composite composed of aggregate,mortar and the ITZ (Interfacial Transition Zone) phase for simplification.Algorithms for generating,distributing and meshing of random convex polyhedrons were programmed.Reduced order homogenization theory was proposed to reduce the calculation capacity with the mesoscale model,by which the mesoscale model of concrete was preprocessed and a two-scale algorithm was constructed.Uniaxial static compression simulations of concretes with different strengths were conducted with the two-scale algorithm.It was shown that the two-scale simulation results agreed well with both the experimental results and the mesoscale simulation results.The reduced order homogenization theory was proved to possess both high efficiency and high accuracy in multiple scale analysis of concrete.