The Numerical Simulation Of Mesoscopic Damage And Failure Process Of Concrete

Concrete is a heterogeneous material which is widely used in many engineering. The traditional macroscopic mechanical models characterize the concrete as a continuum and use the test results as the mechanical properties of the material to satisfy the engineering requirement. But it is difficult to use these models to study the complete failure process caused by the initiation, propagation and coalescence of cracks when subjected external loading. In this article, concrete is taken as a three-phase composite material consisting of matrix, aggregate and the bond between them, and the macro-level mechanical properties are simulated.Firstly, the meso-mechanics analysis on the basis of numerical random aggregate model can provide convincing theorical and numerical supports for the macroscopic strength analysis of concrete structure. According to the objective various aggregate grading curves, an improved numerical method is presented in this paper for the aggregate nuermical generation with random shape and particle size, which break the numerical limit of convex aggregates in other common methods. During the aggregate generation process, techniques of distinguishing overlap regions and filling complex regions on the computer graphics are used to remove the regional overlap in the packing process. The definition of dimensional extreme ratio for particle size is proposed to control the figure of random rock aggregates. Also, an effective method under a little artificial interference is adopted in the forming process of concrete mesomechanics model to improve the successful probability.Secondly, the macroscopic properties of concrete are dependent on the area fractions, mechanical and physical properties, and interaction of the three phases to a great extent. Therefore, the structural characteristics of ITZ are studied, which is of theoretical and practical significance for further understanding of the macroscopic behavior of concrete. After the numerical simulation concrete specimen is built, interface laminar element is established which reflects the interface factor and improves the efficiency and precision of mesoscopic concrete model.On this basis, proportions of components as well as interface thickness impact on the interface elements are studied, and then its influence on macro-level strength of concrete specimen is investigated. Meanwhile, the reliability of random mechanical parameters and the influencing factors, such as constraint condition and grid size are researched. Finally, according to the problems in ANSYS calculation, a program named FEP_CONCRETE is developed to solve the relative problems. Compared with the solution of ANSYS, partial function of this program is analyzed and verified.