Discrete element method for modelling solid and particulate materials

Abstract

SUMMARYThe discrete element method (DEM) is developed in this study as a general and robust technique for unified two-dimensional modelling of the mechanical behaviour of solid and particulate materials, including the transition from solid phase to particulate phase. Inter-element parameters (contact stiffnesses and failure criteria) are theoretically established as functions of element size and commonly accepted material parameters including Young's modulus, Poisson's ratio, ultimate tensile strength, and fracture toughness. A main feature of such an approach is that it promises to provide convergence with refinement of a DEM discretization. Regarding contact failure, an energy criterion based on the material's ultimate tensile strength and fracture toughness is developed to limit the maximum contact forces and inter-element relative displacement. This paper also addresses the issue of numerical stability in DEM computations and provides a theoretical method for the determination of a stable time-step. The method developed herein is validated by modelling several test problems having analytic solutions and results show that indeed convergence is obtained. Moreover, a very good agreement with the theoretical results is obtained in both elastic behaviour and fracture. An example application of the method to high-speed penetration of a concrete beam is also given.

A bond model for DEM simulation of cementitious materials and deformable structures

“…If the value of η is increased above unity, bonds are formed between particles which are not necessarily in direct contact, this is a similar formulation to models [e.g. [34][35][36] but different to others [e.g. 6] where physical particle overlap is required for a bond to form.…”

Using the discrete element method to simulate brittle fracture in the indentation of a silica glass with a blunt indenter

“…Within the discrete element approach, cracks are simulated by breaking bonds that reach a particular criterion (23,24,25,26,27,28). This approach mimics crack extension in a material.…”

Influence of Back Electrostatic Field on the Collection Efficiency of an Electrostatic Lunar Dust Collector

“…Since a Cartesian grid discretizes the ELDC geometry into 3D cells, detecting particle collisions for each particle is limited to the cell confining the target particle and the adjacent grid cells. DEM discretization promises to provide a better numerical convergence with refinement of the grid cells (Tavarez and Plesha, 2007). Sensitivity analysis on grid cell size demonstrated that grid sizes finer than 0.2 mm do not influence the obtained particle trajectories.…”

“…The time step in DEM modeling is a function of particle stiffness and mass of the smallest particle (Tavarez and Plesha, 2007). Depending on particle concentration, 20% to 40% of the Rayleigh time step has been suggested as the suitable time step for EDEM program.…”