Automatic Generation Method For The Finite Element Model Of The Concrete Aggregate

It is necessary to build the computational model in the multi-scale numerical simulation of mechanical properties of heterogeneous materials such as the concrete material. The computational modeling of heterogeneous materials composes of the generations of geometric model of aggregate distribution and the finite element mesh of composite material. The paper proposes a method to generate automatically the geometric model and the finite element mesh with randomly distributed aggregates. With the given size, shape and density, the aggregates with circular, elliptic, or polygonal cross-section shapes are located randomly into a 2D rectangular domain first. Then, the finite element mesh of this geometric model composed of aggregates and base materials are generated with the improved advanced front technology (AFT). The front edge is classified into active one and languid in the AFT, we consider both the scale and the kind of the front edge. It can not only generate high quality mesh in the border, but also satisfy the need of getting various elements. In order to test the efficiency of the method, this paper analyze the statistical characterization of the aggregate distribution. Simulation results show that the aggregate distribution density at any point in concrete converges asymptotically to a constant when the number of simulations tend to infinity, and that the shapes of aggregate distribution density curves for different aggregate areal fractions are remarkably similar, which all consist of three parts: ascending, descending and horizontal, based on these simulated results, the aggregate distribution density and the thickness of boundary layers are expressed as functions of aggregate areal fraction of concrete. Our method is efficient by the test of theory and experiment. The research of this paper provides an efficient automatic modeling method for the computer numerical simulation of heterogeneous materials.