Shear test as calibration experiment for DEM simulations: a sensitivity study

Abstract

Purpose The effect of micromechanical parameters on the macromechanical behaviour of granular materials is analysed by using discrete element based model of the standard shear test. Design/methodology/approach Discrete element method based standard shear test simulations. Findings The approximate mathematical functions related to the effects of DEM micromechanical parameters density, Young-modulus, Poisson number, frictional angle, bond normal cohesion, bond tangential cohesion, rolling friction and particle shape on the macromechanical parameters of shear failure line (internal friction and cohesion) are determined by modelling large number of standard shear tests. Originality/value By knowing these effects of micromechanical parameters to the macromechanical behaviour of the simulated particle assembly, the calibration of discrete element models can be significantly accelerated.

Reducing computational time of cohesionless discrete simulations based on particle clusters

“…As against the results of parameter sensitivity test according to cohesive contact model – which is described in our earlier work (Keppler et al , 2016) – the effect of every micromechanical parameter is linear in our examination range in the course of using cohesionless contact model. All micro-parameters have an opposite influence on both macro-parameters, which means the changing of a single micromechanical parameter cannot be applicable to scaled-up particles; normally, at least changing two micro-parameters is necessary (in case of this set of initial parameters and this examination range).…”

“…To simulate macro-behavior of granular assemblies’ modified version of Jenike’s apparatus, a rectangular shear cell was used with sizes 0.1 × 0.1 × 0.05 m 3 . Steps of simulation are preciously shown in our earlier work (Keppler et al , 2016). To determine reference cohesion ( c ref ) and internal friction angle ( φ ref ) values, spherical elements with a radius 1 mm and randomly selected micromechanical parameters (Table I) with cohesionless contact model were used.…”

“…Based on our earlier work (Keppler et al , 2016), value of simulation timestep was the same in all simulations: Δt =50 percent (per cent of critical time step). After determination of reference macro-behaviors ( c ref = 0.045 kPa, φ ref = 45.76°), a sensitivity test was made to chart effect of different micromechanical parameters on cohesion and internal friction angle.…”

“…The aim of this paper is to examine the possibility that the computational time reduction of discrete simulations is based on a granule’s clustering. Using our earlier work (Keppler et al , 2016), standard shear test and linearized failure curve of particulate materials were applied to model the macro-behavior of the whole system, wherewith in this way, it is possible to define micro-parameters which could be used in a wide range of compression forces. During simulations, spherical elements with cohesionless material properties were investigated, taking into consideration the effect of the scaling up of particle diameter.…”

Application of the Discrete Element Method for Manufacturing Process Simulation in the Pharmaceutical Industry

“…Young’s modulus and static and rolling friction coefficients were confirmed to have a significant effect on pre-shear stress but Poisson’s ratio and coefficient of restitution did not have a significant effect. Besides the ring shear test, Keppler conducted a sensitivity study to accelerate the calibration based on the standard shear test referred to as Jenike shear cell [160]. The sensitivity study was performed to identify the effect of input parameters (e.g., density, Young’s modulus, Poisson’s ratio, coefficient of friction, bond normal cohesion and bond tangential cohesion) on the particle dynamics (i.e., internal friction angle and cohesion) obtained by Jenike shear cell.…”