scholarly journals Damage Simulation of a Random Aggregate Model Induced by Microwave under Different Discontinuous Ratios and Exposure Times

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yang Tang ◽  
Guobin Xu ◽  
Chunlai Qu ◽  
Liying Sun ◽  
Yu Duan
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Particle Flow Code ◽  
Aggregate Model ◽  
Two Phase ◽  
Random Aggregate ◽  
Random Aggregate Model ◽  
Damage Simulation ◽  
Radial Network ◽  
Element Method

A random aggregate algorithmic method and a numerical model for two-phase materials (composed of quartz and plagioclase) with different discontinuous ratios and irradiation times were studied based on the discrete element method using two-dimensional particle flow code (PFC2D). The results showed that this algorithm can simulate random irregular aggregate shapes. Furthermore, crack initiation and development and the coalescence process of microwave-induced material damage could be predicted using the discrete element method. After analysis of this study, the micro crack originated from the boundary of the high-absorption-phase plagioclase crystal and expanded around the plagioclase, extending into the quartz material. The crack morphology presented a radial network.

scholarly journals Modeling of Interior Ballistic Gas-Solid Flow Using a Coupled Computational Fluid Dynamics-Discrete Element Method

2013 ◽  
Vol 80 (3) ◽  
Author(s):  
Cheng Cheng ◽  
Xiaobing Zhang
Keyword(s):  
Discrete Element Method ◽  
Gas Phase ◽  
Two Phase Flow ◽  
Discrete Element ◽  
Particle Collision ◽  
Contact Detection ◽  
Reconstruction Method ◽  
Phase Flow ◽  
Two Phase ◽  
Element Method

In conventional models for two-phase reactive flow of interior ballistic, the dynamic collision phenomenon of particles is neglected or empirically simplified. However, the particle collision between particles may play an important role in dilute two-phase flow because the distribution of particles is extremely nonuniform. The collision force may be one of the key factors to influence the particle movement. This paper presents the CFD-DEM approach for simulation of interior ballistic two-phase flow considering the dynamic collision process. The gas phase is treated as a Eulerian continuum and described by a computational fluid dynamic method (CFD). The solid phase is modeled by discrete element method (DEM) using a soft sphere approach for the particle collision dynamic. The model takes into account grain combustion, particle-particle collisions, particle-wall collisions, interphase drag and heat transfer between gas and solid phases. The continuous gas phase equations are discretized in finite volume form and solved by the AUSM+-up scheme with the higher order accurate reconstruction method. Translational and rotational motions of discrete particles are solved by explicit time integrations. The direct mapping contact detection algorithm is used. The multigrid method is applied in the void fraction calculation, the contact detection procedure, and CFD solving procedure. Several verification tests demonstrate the accuracy and reliability of this approach. The simulation of an experimental igniter device in open air shows good agreement between the model and experimental measurements. This paper has implications for improving the ability to capture the complex physics phenomena of two-phase flow during the interior ballistic cycle and to predict dynamic collision phenomena at the individual particle scale.

Study on Initial States of Steel Balls in Mill by Discrete Element Method

2012 ◽  
Vol 546-547 ◽  
pp. 120-124
Author(s):  
Ping Zhou ◽  
Jing Hong Du ◽  
Xi Xiang Duan
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Three Dimensions ◽  
Particle Flow Code ◽  
Filling Rate ◽  
Initial State ◽  
State Models ◽  
Steel Balls ◽  
Small Steel ◽  
Element Method

Based on Discrete Element Method(DEM), initial state models of steel balls were establisheded by Particle Flow Code in three Dimensions (PFC 3D), the initial void rate of steel balls at different filling rate were calculated. The results showed that at the same filling rate, the initial void rate of steel balls decreased as steel ball’s diameter decreased. The initial void rate of steel balls with one diameter and grading steel balls both increased gradully as ball filling rate increased, but the initial void rate of grading steel balls were smaller than that of steel balls with one diameter. The Stratification phenomenon will occur after steel balls in grading scheme reached to the initial equilibrium sates, that is, Large steel balls moved near the mill’s center, but small steel balls moved away from the mill’s center and close to the cylinder of mill, which is benifical to improve grinding effeciency.

scholarly journals Application of Base Force Element Method to Mesomechanics Analysis for Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yijiang Peng ◽  
Yao Wang ◽  
Qing Guo ◽  
Junhua Ni
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fracture Process ◽  
Damage Mechanics ◽  
Hardened Cement ◽  
Aggregate Model ◽  
Random Aggregate ◽  
Random Aggregate Model ◽  
Force Element ◽  
Element Method

The base force element method (BFEM) on damage mechanics is used to analyze the compressive strength, the size effects of compressive strength, and fracture process of concrete at mesolevel. The concrete is taken as three-phase composites consisting of coarse aggregate, hardened cement mortar, and interfacial transition zone (ITZ) on mesolevel. The random aggregate model is used to simulate the mesostructure of concrete. The mechanical properties and fracture process of concrete under uniaxial compression loading are simulated using the BFEM on damage mechanics. The simulation results agree with the test results. This analysis method is the new way for investigating fracture mechanism and numerical simulation of mechanical properties for concrete.

Numerical Studies of Cutting Water Saturated Sand by Discrete Element Method

2012 ◽  
Vol 256-259 ◽  
pp. 306-310 ◽  
Author(s):  
Shao Hua Qin ◽  
Li Quan Xie ◽  
Guo Jun Hong ◽  
Jie Wang
Keyword(s):  
Discrete Element Method ◽  
Sandy Loam ◽  
Static Friction ◽  
Discrete Element ◽  
Particle Flow Code ◽  
Saturated Sand ◽  
Model Soil ◽  
Water Saturated ◽  
Cutting Model ◽  
Element Method

The discrete element method (DEM) has been recognized as an effective tool to simulate soil–tool interactions. In this study, a saturated sand cutting model is developed using a commercial DEM software, Particle Flow Code in Two Dimension (PFC 2D). In the model, soil are defined as particles with the basic PFC 2D model, full coupling with a deformable fluid. The mechanical interactions between particles and also between particles and the walls are modeled by sprints, dash-pots and friction sliders. The properties of the material and interactions (Poisson’s ratio, shear modulus and density, coefficients of restitution, rolling and static friction) relate to the particle properties and not to the bulk properties. Such quantitative and qualitative models are essential for improving the design, selection and use of water saturated sand cutting implements, in different field sand under different conditions. This paper describes a numerical experimental investigation of the failure characteristics of two-dimensional water saturated sand cutting. Comprehensive simulated tests were carried out on sandy loam using a box apparatus and two model plane blades of rake angles 30º, 60º and two angles of friction 32º,42º, respectively. Besides, there are two extreme densities of the sand, compacted and loose. These factors should provide a basis for the reliable prediction of the failure type.

Reasearch on Movements of Grading Steel Balls in Mill by Discrete Element Method

2012 ◽  
Vol 546-547 ◽  
pp. 115-119
Author(s):  
Ping Zhou ◽  
Jing Hong Du ◽  
Xi Xiang Duan
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Three Dimensions ◽  
Particle Flow Code ◽  
Filling Rate ◽  
Rotary Speed ◽  
Steel Balls ◽  
Grinding Efficiency ◽  
Throwing Motion ◽  
Element Method

Based on Discrete Element Method(DEM), movements of steel balls in ball mill were simulated by Particle Flow Code in three Dimensions (PFC 3D), the motion states of all steel balls and balls with one diameter were discussed respectively at different ball filling rate. The results indicated that steel balls moved from cascading motion gradually to throwing motion with the increasing of rotary speed rate, and became centrifugal motion after rotary speed rate exceeded certain value. When rotary speed rate unchanged, the translation speeds from cascading to throwing or from throwing to centrifugal motion accelerated as steel balls’ diameter decreased. The segregation of steel balls was more obvious with the rising of rotary speed rate and lead to steel balls’ lamination that big balls moved in the inner and small balls moved in outer layer of the mill. Lamination of steel balls is benefical to crush different size minerals and improve grinding efficiency.

scholarly journals Modelling of the Separation Process in a Ferrohydrostatic Separator Using Discrete Element Method

2007 ◽  
Vol 2007 ◽  
pp. 1-13 ◽  
Author(s):  
V. Murariu ◽  
P. J. Sergeant
Keyword(s):  
Discrete Element Method ◽  
Flow Behavior ◽  
Discrete Element ◽  
Separation Process ◽  
Spherical Particles ◽  
Particle Flow Code ◽  
Complex Flow ◽  
De Beers ◽  
Simulation Parameters ◽  
Element Method

This paper presents a model of the separation process in a ferrohydrostatic separator (FHS) which has been designed and developed at DBGS, De Beers, South Africa. The model was developed using special discrete element method software package called Particle Flow Code in 3D (PFC3D). Special attention has been paid to the selection of the simulation parameters in order to achieve the required feed rates. The simulation was carried out using spherical particles and density tracers of different sizes and densities ranging between 0.004 and 0.008 m and 2700 and 3800 kg/m3, respectively. The tracers were used to set the apparent density of the ferrofluid (the cut-point) and to provide a measurement of the efficiency of the separation. The model is replacing the ferrofluid by imposing a drag force on the particle. The results of the simulation were presented in the form of the distribution of the density tracers into the sink fraction. These results are realistic and show the advantages of DEM to understand the complex flow behavior of granular materials.

scholarly journals Performance based simulation of pervious concrete using discrete element method

2020 ◽  
Vol 72 (08) ◽  
pp. 693-701
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Pervious Concrete ◽  
Particle Flow ◽  
Particle Flow Code ◽  
The Finite Element Method ◽  
Ordinary Concrete ◽  
Paste Content ◽  
Highly Porous ◽  
Element Method

Pervious concrete is a special type of concrete that differs from ordinary concrete by its highly porous nature, which is why this type of discrete material can not be modelled using the Finite Element Method (FEM). Behaviour of pervious concrete samples with different aggregate sizes and void ratios is simulated in the paper, using the Particle Flow Code (PFC) software, which is based on the discrete element method (DEM). The PFC software is used to simulate various experimental results obtained on high paste content pervious concrete samples.

Random field generation of the material properties in the lattice discrete element method

2019 ◽  
Vol 54 (4) ◽  
pp. 236-246 ◽  
Author(s):  
Vicente Bergamini Puglia ◽  
Luis Eduardo Kosteski ◽  
Jorge Daniel Riera ◽  
Ignacio Iturrioz
Keyword(s):  
Discrete Element Method ◽  
Random Field ◽  
Three Dimensional ◽  
Discrete Element ◽  
Simulation Process ◽  
Random Field Generation ◽  
Damage Simulation ◽  
Random Nature ◽  
Nonhomogeneous Materials ◽  
Element Method

The lattice discrete element method has been successfully used to simulate the evolution of damage in structural mechanics. The approach has led to new perspectives in the solution of fracture problems in nonhomogeneous materials. For such purpose, it is necessary to introduce correctly the parameters that characterize the random nature of the material. In this article, the fracture toughness of the material is considered a three-dimensional random field, characterized by a probability density and the spatial distribution of the simulated random field which is governed by the correlation length. The methodology used to separate the random field simulated from the discretization level used is depicted in detail. Examples are shown that verify the objectivity of the results obtained respecting the discretization levels. Finally, the article concludes by emphasizing the relevance of this implementation in the damage simulation process in the so-called heterogeneous materials.

Modeling of Anchors in Gravel Formation Using Discrete Element Method

2011 ◽  
Vol 189-193 ◽  
pp. 1726-1731 ◽  
Author(s):  
Sung Chi Hsu ◽  
Bo Jing Lai ◽  
Wei Hsu ◽  
Juir Ren Lai
Keyword(s):  
Discrete Element Method ◽  
Three Dimensional ◽  
Friction Angle ◽  
Discrete Element ◽  
Particle Flow Code ◽  
Pullout Resistance ◽  
Direct Shear Tests ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Element Method

The subject of this research mainly focuses on the gravel formation along the western foothill of Taiwan. Numerical simulations are performed using discrete element method (DEM) based the software Particle Flow Code (PFC). Physical properties and internal friction angle of gravels are obtained from the three dimensional modeling of in-situ direct shear tests. The numerical experiments using PFC2D are used to model single-vertical anchor installed at shallow depths. The numerical results indicate that the failure range for the tension-type anchor is smaller than the range for compression-type anchor at the same bonded length and friction angle. The pullout resistance for the compression anchor is also greater than the tension anchor. Similar results have been obtained from the field pullout tests. The transmission of forces along the anchor is significantly affected by way of particle permutation with the anchor. If bigger size particles are piled around the anchor, the transmission of forces along the anchor will be faster and the affecting range of particles is also larger.

Sign in / Sign up

Export Citation Format

Share Document