Three-Dimensional Finite-Element Modeling for Asphalt Concrete Using Visual Cross-Sectional Imaging and Indirect Element Meshing Based on Discrete-Element Models

Abstract

Numerical simulation for asphalt concrete using the finite-element (FE) method has been widely explored during the last few decades. However, the FE model reconstructions for asphalt concrete samples are mainly limited to the X-ray imaging approach. Although some computer-generated FE models have been used in previous studies, related work is still at a very preliminary stage. Different from FE modeling for asphalt concrete, discrete element (DE) modeling has been well developed using user defined aggregate models with the aid of commercial software. This study aims to bridge the DE models with FE models for asphalt concrete by using virtual cross-sectional imaging and indirect cubic element meshing. In the first approach, virtual cross-sectional imaging is conducted to identify the areas occupied by aggregate particles and air voids. These virtual cross-sectional images are afterward stacked to form three-dimensional (3D) solid models. Then, the 3D solid models are triangularly meshed and imported into the FE simulation software, ABAQUS. By this means, an FE model with tetrahedral elements is reconstructed. In the second approach, arranged spheres are generated to fill the entire sample first. The circumscribed cubes of the spheres are found and regarded as the cubic elements in FE models. An input file containing elemental and nodal information is directly written by PFC3D using user-written functions. Then the input file is imported into ABAQUS, and an FE model with hexahedral elements is reconstructed. This study provides a new and effective approach for FE model reconstruction of asphalt concrete with user defined aggregate and air void models. Additionally, the advantages and limitations of the two approaches are discussed.