Abradable DEM: A novel framework to capture the mechanistic evolution of particle shape
Description
Although various methods exist for modelling non-spherical particles in DEM, particles’ shapes are usually treated as immutable. However, particles often change shape gradually, e.g., due to abrasion or accrued plastic deformation. This manner of shape evolution has largely been neglected in DEM, even though it can significantly influence bulk-scale behaviour. The following introduces an extendable framework for modelling the gradual and permanent evolution of particle shapes in DEM, focusing on abrasion. By extending the LAMMPS rigid-body implementation, a comprehensive novel wear model is adapted to simulate the abrasion of arbitrarily shaped particles. Abradable particles are represented as hollow shells of discrete spheres which compute forces via standard pair interactions. These spheres form the nodes of a triangulated mesh used to calculate well-defined local surface areas and normals. Following an impact exceeding a material yield criterion, spheres are displaced inwards along their associated normals. The result is a reduction in volume and a permanent change in shape. Each abraded particle’s moment of inertia is then recomputed to resolve future rigid-body dynamics. Thus, particle-level changes in shape affect the system’s bulk dynamics, which in turn informs subsequent abrasion. Results exhibit shape evolution in agreement with a variety of abrasion scenarios in literature and showcase the consequent effect on their bulk dynamics. By linking microscale abrasion mechanisms to macroscale system behaviour, the present research has widespread applications in both natural processes and industrial particle-handling systems. Furthermore, the outlined framework can be readily adapted to other sources of mechanistic particle shape evolution in DEM.