Frictional Collapse of Granular Assemblies

2004 ◽  
Vol 71 (3) ◽  
pp. 350-358 ◽  
Author(s):  
Akke S. J. Suiker ◽  
Norman A. Fleck
Keyword(s):  
Coulomb Friction ◽  
Relative Proportion ◽  
Element Model ◽  
Discrete Element ◽  
Triaxial Tests ◽  
Discrete Element Model ◽  
Granular Assembly ◽  
Granular Assemblies ◽  
Constitutive Response ◽  
Good Agreement

The frictional collapse of an assembly of equisized spheres is studied by a discrete element model. The macroscopic constitutive response is determined as a function of the level of Coulomb friction between particles. It is found that the level of Coulomb friction has a strong effect upon the relative proportion of sliding and rolling between particles, and consequently upon the macroscopic strength of the granular assembly. The discrete element predictions are shown to be in good agreement with experimental results obtained from triaxial tests on an aggregate of steel spheres. It is demonstrated that the shape of the collapse surface can be adequately represented by the Lade-Duncan continuum model.

Parameter Determination of Discrete Element Model of Conditioned Soil by Genetic Neural Network

2010 ◽  
Vol 150-151 ◽  
pp. 27-31
Author(s):  
Li Wu ◽  
Tian Min Guan ◽  
Fu Zheng Qu ◽  
Shou Ju Li
Keyword(s):  
Neural Network ◽  
Triaxial Test ◽  
Element Model ◽  
Discrete Element ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Discrete Element Model ◽  
Discrete Element Simulation ◽  
Element Simulation ◽  
Genetic Neural Network

The inversion method combining the genetic neural network and the discrete element simulation of triaxial tests is firstly described for determining the discrete element model parameters of the conditioned soil. The purpose is to make the error of the simulation curves and the laboratory curves of the triaxial test minimum. The solve approach is the parameters identification based on the genetic neural network. The network training sample is provided by the discrete element simulation. The input sample is the simulation curves of triaxial test, and the output sample is the model parameters. The laboratory triaxial test curves of the conditioned soil are used to determine its model parameters. The simulation curves calculated with the inversed parameters match the laboratory curves well, which illustrate that the discrete element model can accurately predict the deformation characteristics and flow patterns of conditioned soils.

scholarly journals A Quantitative Discrete Element Model to Investigate Sub-Surface Damage due to Surface Polishing

2012 ◽  
Author(s):  
Damien André ◽  
Ivan Iordanoff ◽  
Jean-luc Charles ◽  
Jérôme Néauport
Keyword(s):  
Experimental Data ◽  
Silica Glass ◽  
Surface Damage ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model ◽  
Continuous Part ◽  
Surface Polishing ◽  
Quantitative Results ◽  
Good Agreement

This work is a continuation of a previous study that investigated sub-surface damage in silica glass due to surface polishing. In this previous study, discrete element models have shown qualitatively good agreement with experiments. The presented work propose a model allowing quantitative results by focusing on the continuous part of the problem. Special attemption was given to the discrete element model of silica glass considered as perfectly isotropic, elastic and brittle. To validate this approach, numerical results are compared to experimental data from literature.

scholarly journals Discrete element model for general polyhedra

2021 ◽  
Author(s):  
Alfredo Gay Neto ◽  
Peter Wriggers
Keyword(s):  
Frictional Contact ◽  
Virtual Work ◽  
Particle Surface ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model ◽  
Principle Of Virtual Work ◽  
Dynamics Model ◽  
Railway Ballast ◽  
Multibody Dynamics Model

AbstractWe present a version of the Discrete Element Method considering the particles as rigid polyhedra. The Principle of Virtual Work is employed as basis for a multibody dynamics model. Each particle surface is split into sub-regions, which are tracked for contact with other sub-regions of neighboring particles. Contact interactions are modeled pointwise, considering vertex-face, edge-edge, vertex-edge and vertex-vertex interactions. General polyhedra with triangular faces are considered as particles, permitting multiple pointwise interactions which are automatically detected along the model evolution. We propose a combined interface law composed of a penalty and a barrier approach, to fulfill the contact constraints. Numerical examples demonstrate that the model can handle normal and frictional contact effects in a robust manner. These include simulations of convex and non-convex particles, showing the potential of applicability to materials with complex shaped particles such as sand and railway ballast.

Study on Machining Mechanism of Glass Using Discrete Element Method

2014 ◽  
Vol 577 ◽  
pp. 108-111 ◽  
Author(s):  
Ying Qiu ◽  
Mei Lin Gu ◽  
Feng Guang Zhang ◽  
Zhi Wei
Keyword(s):  
Discrete Element Method ◽  
Element Model ◽  
Discrete Element ◽  
Rake Angle ◽  
Milling Process ◽  
Micro Milling ◽  
Discrete Element Model ◽  
Machined Surface ◽  
Damage Depth ◽  
Element Method

The discrete element method (DEM) is applied to glass micromachining in this study. By three standard tests the discrete element model is established to match the main mechanical properties of glass. Then, indentating, cutting, micro milling process are simulated. Results show that the vertical damage depth is prevented from reaching the final machined surface in cutting process. Tool rake angle is the most remarkable factor influencing on the chip deformation and cutting force. The final machined surface is determined by the minimum cutting thickness per edge. Different cutting thickness, cutter shape and spindle speed largely effect on the mechanism of glass.

Reduced Rough-Surface Parametrization for Use With the Discrete-Element Model

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Stephen T. McClain ◽  
Jason M. Brown
Keyword(s):  
Heat Transfer ◽  
Rough Surface ◽  
Surface Characterization ◽  
Rough Surfaces ◽  
Roughness Element ◽  
Three Dimensional ◽  
Element Model ◽  
Discrete Element ◽  
Diameter Distribution ◽  
Discrete Element Model

The discrete-element model for flows over rough surfaces was recently modified to predict drag and heat transfer for flow over randomly rough surfaces. However, the current form of the discrete-element model requires a blockage fraction and a roughness-element diameter distribution as a function of height to predict the drag and heat transfer of flow over a randomly rough surface. The requirement for a roughness-element diameter distribution at each height from the reference elevation has hindered the usefulness of the discrete-element model and inhibited its incorporation into a computational fluid dynamics (CFD) solver. To incorporate the discrete-element model into a CFD solver and to enable the discrete-element model to become a more useful engineering tool, the randomly rough surface characterization must be simplified. Methods for determining characteristic diameters for drag and heat transfer using complete three-dimensional surface measurements are presented. Drag and heat transfer predictions made using the model simplifications are compared to predictions made using the complete surface characterization and to experimental measurements for two randomly rough surfaces. Methods to use statistical surface information, as opposed to the complete three-dimensional surface measurements, to evaluate the characteristic dimensions of the roughness are also explored.

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