Aggregate Representation Approach in 3D Discrete-Element Modeling Supporting Adaptive Shape and Mass Property Fitting of Realistic Aggregates

Accurate representations of aggregates in stone-based materials are crucial to conducting reliable discrete-element (DE) simulations based on the microstructure of such materials. The objective of this study was to develop an adaptive representation method for aggregates to obtain corresponding clumps of spheres that closely fit realistic shapes and the inertia of the aggregates. Based on the developed three-dimensional (3D) solid model of each aggregate, the methodology consisted of three main steps, as follows: (1) the aggregate contour was displaced with surface spheres of different sizes in predefined fitting accuracy; (2) consequently, the internal space of the model was filled with inner spheres; and (3) eight spheres for inertia calibration were incorporated, with the sphere clump consisting of surface and inner spheres to generate the DE representation of the aggregate. DE representations of 11 aggregate particles were developed using the proposed method. Results imply that the obtained DE representation can occupy the volume of the aggregate more than 99.5% with a properly defined fitting accuracy and fit the aggregate in inertia very well. A numerical simulation of asphalt mixture compaction was conducted using the aggregate models generated in this study. The numerical simulation indicates that the aggregate models generated using the proposed method can be successfully used to generate stone-based materials such as asphalt mixtures