DEM Software Research Articles

Bitumen and mastic local rupture test modelling with DEM

We present some preliminary results of a national research project dealing with the wearing course damage and the tire–pavement interactions with traffic loadings, where asphalt concrete raveling test and its modelling are ongoing studies. For this, we used the Local Fracture Test (LFT) or the French acronym RULOB test, developed by Gustave Eiffel University, to analyse the fracture behaviour of bitumen and mastic. The test reproduced a film of binder placed between two aggregates under defined loading conditions. The results of the test highlighted the influence of the loading conditions on the failure scenarios encountered, and the different ageing conditions (RTFOT, RTFOT+PAV). The role of filler in the bitumen (mastic) is also investigated in the same way. The study also attempted to reproduce the experimental test using the DEM software LMGC90. The results agree with the next step of our ongoing study which is to model ravelling tests of asphalt concrete.

Study Of Particles Flow Over Industrial Wobbler Type Feeder Using Discrete Element Method

Wobbler feeders are generally used to feed coarse material to the primary crusher in the mine and aggregate applications. In the operation, finer particles are also screened through the spaces among rollers and wobbling of the rocks through the roller cause impact and rubbing effect that helps to move undesired particle over batches. Motion of the materials on the feeder depends on design parameters such as roller size, rotation speed, spacing etc. and also gradation of the bulk material that fed into the feeder. The performance investigation of the feeder heavily relies on experimental studies due to complex motion of the material on the feeder as well as particle interaction in the batch. Discrete Element Method is a method that used to compute motion of large number of particles in a granular flow and it is widely accepted as an effective method in the rock mechanics. In this study, DEM is used to investigate the performance of a wobbler feeder. The feeder is designed and simulated for different parameters such as spacing, roller speed, particle shape and gradation in The Rocky DEM software. The particle velocities and trajectories were determined, and particle resident times were calculated to investigate the efficiency of the feeder for different disc configurations.

DEM-based 2D numerical simulation of the rock cutting process using a conical pick under confining stress

Many factors influence rock breakage during cutting processes, including cutting parameters (attack angle, cutting depth and cutting spacing), rock properties and stress conditions. The influence of confining stress on the linear cutting process is currently not well understood. In this study, a 2D discrete element numerical model is developed utilizing DEM software to simulate the linear cutting process of rock using a conical pick. The model accounts for different levels of confining stress to investigate their effect on the cutting process. The numerical model was first validated to ensure its rationality. Subsequently, the rock breakage process under different confining stresses was analysed by observing variations in cutter force, the development of crack extension, particle displacement, velocity variations, and alterations in internal stress. According to the results, the presence of confining stress facilitated the propagation and expansion of cracks within the original rock, particularly along the region where the free surface was present. Subsequently, during the cutting process under different stress conditions, it was observed that as the confining stress increased, the length of radial crack expansion decreased gradually along the tip of the cutter. Under higher stress conditions, a uniform distribution of mostly tensile cracks appeared inside the rock during the cutting process. Additionally, the regression analyses show that average cutting force and specific energy for rock breakage both exhibit an initial increase, followed by a decrease, with increasing confining stress. This indicates that the rock breakage efficiency was high when the confining stress was low and that a high confining stress can instead improve rock cutting. Through these analyses, insights were gained into the mechanisms underlying rock breakage during the linear cutting process using a conical pick under different levels of confining stress. Ultimately, these findings provide valuable knowledge for predicting and optimizing rock cutting processes under different stress conditions.

Implementation of a viscoelastic boundary condition to Yade – open source DEM software

1. Brzeziński K., Gladky A., 2022, Clump breakage algorithm for DEM simulation of crushable aggregates, Tribology International, 173, 107661. CrossRef Google Scholar

Определение статических нагрузок на борт грузовой платформы карьерного самосвала

The article considers design schemes for determining static loads on the body sides of a mining dump truck. Methods for determining the static loads are described. Calculations of the pressure on the retaining wall using an analytical method were carried out. Simulation modeling of the body side loading with the method of discrete elements using the Rocky DEM software was performed. The parameters for discrete elements (with coal as the bulk material) are given. The calculated values and the previously obtained values of physical tests and studies are analyzed. Graphs and dependences of the influence of the body side height on the pressure on the retaining wall are obtained. Recommendations are given for determining the active pressure on the body side of a mining dump truck.

On the need to classify rock mass fed to dry magnetic separation

The hypothesis of a possible use of dry magnetic separation is substantiated on the example of ores from ferruginous quartzite deposits operated by plants of PAO “Severstal” Holding. Size class of ore after medium crushing is –80+0 mm when the vibrating feeder is used for feeding ore mass to the separation zone. The rationale is based on the analysis of video recording of physical simulation on a laboratory drum magnetic separator of SMBS-L series, in the VSDC Video Editor, and simulation modelling of dry magnetic separation on its virtual prototype in Rocky DEM software package. It has been proved that the use of a vibrating feeder for feeding the material to the working area of a magnetic separator makes it possible to: form a monolayer on the surface of the vibrating feeder chute with a thickness close to the maximum size of a lump of separated ore; implement batch feed of material to the separation zone; increase the spacing between lumps in the separation zone when passing through the free fall area, thereby allowing dry magnetic separation of ferruginous quartzites of size class –80+0 mm without pre-preparation.

Study on Drilling Ground Collapse Induced by Groundwater Flow and Prevention Based on a Coupled CFD-DEM Method

Given the hazards caused by drilling ground collapse (DGC) due to groundwater flow in the processes of geotechnical engineering investigation, a coupled computational fluid dynamics and discrete element method (CFD-DEM) method is adopted to numerically simulate the development of hazards. An improved coupling program is employed to realize the two-way coupling between open-source CFD code OpenFOAM and commercial DEM software PFC3D. The coupling program allows complex meshes generated by ANSYS ICEM to be imported into PFC3D. The feasibility and accuracy of the CFD-DEM method are first verified by simulating a single spherical particle settling in hydrostatic water and the formation of the repose angle of sandpiles. Then, this method is adopted to investigate the patterns of stratum deformation and foundation loss, typical particle flow processes, and characteristics of drilling rig toppling. Finally, measures for prevention of DGC induced by groundwater flow are discussed in detail. Two typical strata, including a water-rich sand stratum and a water-rich sand-clay compound stratum, are considered. The research results show that for the water-rich sand stratum, DGC induces a “bowl”-shaped settlement trough, and the maximum value of ground surface settlement is proportional to the foundation loss rate. For the water-rich sand-clay compound stratum, a “jar”-shaped settlement trough is created. Four typical particle flow processes are involved in DGC. The drilling rig topples toward the center of the settlement trough. The maximum displacement appears at the top of the tower and has an approximate linear correlation with the groundwater flow velocity. The measures and methods of DGC prevention are also summarized in detail. The results of this research provide a reference for hazard prevention and delicacy control of DGC induced by groundwater flow.

Применение численного и физического моделирования при проектировании конструкции рентгенолюминесцентного сепаратора, предназначенного для разделения руд, содержащих люминесцирующие минералы

The paper demonstrates the application of numerical and physical modeling to justify the design of the X-ray fluorescence separator’s material handling system. The Rocky DEM software package is a numerical modeling tool that uses the discrete element method as a mathematical apparatus. In order to increase the efficiency of the X-ray luminescence separation, the authors suggest including an additional element in the separator’s material handling system, i.e., a drum spreader that combines a handling device and an actuating mechanism. It was found out that the best loading of the drum spreader cells, in which the number of several pieces in one cell is reduced by at least 15%, is provided by a Vibrating feeder conveyor with a triangular cross-section of the profiled part of the tray compared with the tray of parabolic cross-section. In addition, the triangular section provides a double decrease in the number of pieces with rotational movement around their axes and, accordingly, an increase of at least 5% in the average velocity of the ore flow movement along the tray. The simulation of the material handling system has shown the need to reduce the height of the end partition of the drum spreader between the cells to 45 mm, which eliminates the collision of ore pieces with the partition and subsequently, their movement in the direction of rotation of the drum spreader on its outer surface, as well as the unpredictable escape of the ore pieces beyond the working space of the separator.

Experimental and Numerical Study of Volt–Ampere Characteristics of a Packed Tube Heated by Joule Heating

Abstract This work is devoted to experimental and numerical studies of volt–ampere characteristics of a fixed bed heated by Joule heating. The main feature of this type of fixed bed is internal heat generation using the Joule heat. The application is to provide the heat to chemically reacting gases flowing through the bed reactor. To validate our model, a cylindrical packed bed is considered with a height of 11 cm and an internal diameter of 4.8 cm. This bed is filled with 86 balls made of carbon steel with a diameter of 1/2 in. (1.27 cm). For numerical simulation, open-source dem software is used to generate the cylindrical packed bed. Electric field distribution is calculated using a new particle-unresolved discrete element modeling-based model coupled with a discrete heat transfer model to account for the temperature dependency of the electrical conductivity of steel particles. The results of the simulation were found to be in good agreement with experimental data.

Numerical Simulation and Parameters Verification of a Mechanical Model for Wheat Straw with Destructibility Based on Dem Software

Numerical Simulation and Parameters Verification of a Mechanical Model for Wheat Straw with Destructibility Based on Dem Software

Experiments and Performance Evaluation of a New Wheat Seed Shooting Device for the North China Plain

HighlightsA noncontact mechanical wheat seed shooting device was developed for use in the North China Plain.The shooting depth increased with increasing shooting velocity and with increasing shooting angle.The tested parameters were statistically significant for average shooting depth (ASD), coefficient of variation of shooting depth (CVSD), and coefficient of variation of seeding amount (CVSA).The results from bench and field experiments indicated that the performance of the shooting device with the optimized parameters could fully meet the planting requirements for winter wheat in the North China Plain.Abstract. Planting performance is essential for wheat planters and seed emergence. In this study, a noncontact mechanical wheat seed shooting device was developed to simplify the planter structure, eliminate blockage of the soil-contacting parts, and enhance the stability of the sowing depth. A preliminary model of shooting wheat was developed using DEM software to simulate the shooting depth. The modeling results showed general trends of increased shooting depth with increasing shooting velocity and shooting angle, and decreased shooting depth with increasing shooting height. The shooting depth exceeded 30 mm when the shooting velocity of the wheat seeds was greater than 30 m s-1 and the shooting height was less than 150 mm. Additionally, to increase the stability of the sowing depth, this study investigated the effects of three operating parameters (forward speed, rotational speed of the shooting device, and shooting height) on the average shooting depth (ASD), shooting velocity of seed (SVS), coefficient of variation of shooting depth (CVSD), and coefficient of variation of seeding amount (CVSA). The SVS was proposed as an indicator of shooting performance. A three-factor central-composite experiment was performed to understand the parameter interactions and verify the optimal parameter values. The results from bench and field experiments demonstrated that the performance of the shooting device with the optimized parameters could fully meet the sowing requirements for winter wheat in the North China Plain. The ASD, CVSD, CVSA, and SVS of the seed shooting device with the optimized parameters were 34.6 mm, 9.3%, 13.9%, and 35.8 m s-1, respectively. The seed damage rate (SDR), seed germination rate (SGR), and coefficient of variation of seeding uniformity (CVSU) in the field experiment were 0.9%, 88.2%, and 13.5%, respectively. Keywords: Coefficient of variation of shooting depth, Shooting device, Shooting velocity, Winter wheat.

Volume/shear work ratio influence on wear and stress of soil chisel tine modelled by DEM

Agricultural equipment is working in very high-stress conditions. However, it has a significant influence on the wear losses of soil processing parts. Chisel is operating at 30 cm working depth at a maximum of 12 km·h−1 working speed. Due to unpredictable soil conditions, chisel tines suffer high wear losses. It leads to time consumption and cost expenses during the soil preparation period. Wear resistance, and agronomical requirements (working depth, loosening of soil) are the main criteria of agricultural equipment producers. The discrete element method is a solution that simulates soil as sphere shape particles with soil properties. Wear results reveal the change of parts shape, acting forces, and stresses during the simulation in the virtual soil bin. The used Rocky DEM software uses a parameter C (volume/shear work ratio) to describe wear intensity, which varies for different geometry. Chisel tine geometry should be divided into sections with varied parameter C according to stress acting on the surface. The test conditions can be used for future wear analysis of varied tool geometry and protection (sintered tungsten carbide plates, hard-faced surface, etc.) agricultural tools to compare its durability in different soil conditions.

Modification of design of feed chute in a tertiary cone crusher at the Sarcheshmeh copper complex

Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. In this research, the effect of feed chute design on tertiary cone crusher performance at the Sarcheshmeh copper complex was studied. A close monitoring of the performance crusher revealed that main problems were high fluctuations of power draw and uneven and high rate wear of crusher liners. Accordingly, various feed chute designs were employed in the simulations by an in-house developed DEM software called KMPCDEM© to find more uniform feed distribution on the distribution plate of the crusher. Results showed that by changing the shape of feed chute from cubic to cylindrical, decreasing its surface area from 0.34 to 0.24 m2 and increasing the cylinder length above and below the feed chute plate from 0 to 45 cm and from 53 to 95 cm, respectively, uniform feed distribution was obtained. After installing the new feed chute design in the plant, a detail monitoring over a period of 15 months showed a reduction of the standard deviation of crusher power draw from 13 to 3 kW. A better crusher control caused choke feeding. Therefore, 36% increase in the crusher throughput and finer and narrower product size distribution occurred. Furthermore, the life of crusher liners increased from 8 months to 15 months on account of more uniform and lower rate of wear on mantle and liners.

Semi-Autogenous Wet Grinding Modeling with CFD-DEM

The paper highlights the features of constructing a model of a wet semi-autogenous grinding mill based on the discrete element method and computational fluid dynamics. The model was built using Rocky DEM (v. 4.4.2, ESSS, Brazil) and Ansys Fluent (v. 2020 R2, Ansys, Inc., United States) software. A list of assumptions and boundary conditions necessary for modeling the process of wet semi-autogenous grinding by the finite element method is presented. The created model makes it possible to determine the energy-coarseness ratios of the semi-autogenous grinding (SAG) process under given conditions. To create the model in Rocky DEM the following models were used: The Linear Spring Rolling Limit rolling model, the Hysteretic Linear Spring model of the normal interaction forces and the Linear Spring Coulomb Limit for tangential forces. When constructing multiphase in Ansys Fluent, the Euler model was used with the primary phase in the form of a pulp with a given viscosity and density, and secondary phases in the form of air, crushing bodies and ore particles. The resistance of the solid phase to air and water was described by the Schiller–Naumann model, and viscosity by the realizable k-epsilon model with a dispersed multiphase turbulence model. The results of the work methods for material interaction coefficients determination were developed. A method for calculating the efficiency of the semi-autogenous grinding process based on the results of numerical simulation by the discrete element method is proposed.

DEM-based design of feed chute to improve performance of cone crushers

The effect of feed chute design on tertiary cone crusher performance at the Sarcheshmeh copper complex was studied by an in-house developed DEM software called KMPCDEM©. To simulate the overall crushing circuit, the multi-geometry procedure by improving the routines of object files importing into the simulation environment was implemented in DEM codes. The calibration of DEM parameters was performed using the observed angle of the pile formed on the conveyor (surcharge angle). Various feed chute designs were then employed in the simulations based on an experimental design to find more uniform feed distribution on the distribution plate of the crusher. More uniform feed distribution was obtained by changing the shape of feed chute from cubic to cylindrical, decreasing its surface area from 0.34 to 0.24 m2 and increasing the cylinder length above and below the feed chute plate from 0 to 45 cm and from 53 to 74 cm, respectively. This was verified by proximity of center of the mass of distributed feed to the center of crusher distribution plate. After installing the new feed chute design in the plant, a detail monitoring over a period of 15 months showed a reduction of the standard deviation of crusher power draw from 13 to 3 kW. A better crusher control, 36% increase in the crusher throughput and finer and narrower product size distribution were among the main outcomes of the new feed chute. It was concluded that the wear rate on mantle and liners of crusher not only decreased but it also became uniform.

Theoretical study of pneumatic separation of sugarcane bagasse particles

Sugarcane bagasse is a byproduct generated at sugarcane mills after sugarcane juice extraction. Studies on the enzymatic hydrolysis of fine pneumatic classified particles at ambient equilibrium moisture content have shown good cellulose to glucose conversion without any extra pretreatments as milling, enzymatic, acid or a combination of these, which is one of the current hydrolysis process bottlenecks. Avoid such pretreatments is extremely important for reducing process costs. Based on previous work, this study performed a theoretical investigation of bagasse particles' separation aiming a better understanding of this phenomena permitting development and improvement of equipment used for it. Numerical simulations were carried out using ANSYS Fluent® and Rocky® DEM software, which modelled separation experiments based on computational fluid dynamics and discrete element method, respectively. The comparison between simulation and actual experimental results showed that the model is predictive and can be extended to several processes that use the fluidisation of sugarcane bagasse, such as drying, pyrolysis, and gasification. The studied simulation models can also serve as a basis for fluidisation simulations of other biomasses.

The Evolution of Grinding Mill Power Models

Mill power models have been used in a variety of ways in industrial practice since power directly equates to throughput and fineness of ground product. We first start with Hogg-Fuerstenau Power Model and show how this model successfully predicted the power draw of many grinding mills in several mining operations. Then, we show how this model was on the verge of being able to predict the influence of lifter design on power draw. Next, we describe the discrete element model and how it overcame the issues faced by the previous power model. Using a DEM software known as Millsoft, we show the influence of lifter design geometry on power draw and analyze the power draw of rubber lifters versus the steel lifters via several case studies. As years passed, the two-dimensional discrete element model imbedded in Millsoft is superseded by three-dimensional discrete element method. Due to the gigantic computational power of graphic processing units, new computational codes that can do the tumbling motion along the entire length of the mill has come about. Here, we show the predictive capability of Blaze-DEM for ball and SAG mills.

A parallel dual-grid multiscale approach to CFD–DEM couplings

In this work, a new parallel dual-grid multiscale approach for CFD–DEM couplings is investigated. Dual-grid multiscale CFD–DEM couplings have been recently developed and successfully adopted in different applications still, an efficient parallelization for such a numerical method represents an open issue. Despite its ability to provide grid convergent solutions and more accurate results than standard CFD–DEM couplings, this young numerical method requires good parallel performances in order to be applied to large-scale problems and, therefore, extend its range of application. The parallelization strategy here proposed aims to take advantage of the enhanced complexity of a dual-grid coupling to gain more flexibility in the domain partitioning while keeping a low inter-process communication cost. In particular, it allows avoiding inter-process communication between CFD and DEM software and still allows adopting complex partitioning strategies thanks to an optimized grid-based communication. It is shown how the parallelized multiscale coupling holds all its natural advantages over a mono-scale coupling and can also have better parallel performance. Three benchmark cases are presented to assess the accuracy and performance of the strategy. It is shown how the proposed method allows maintaining good parallel performance when operated over 1000 processes.

Multi-scale response sensitivity analysis based on direct differentiation method for concrete structures

As traditional composite materials, concrete and reinforced concrete (RC) have been widely used for civil and military purposes. The multi-scale response analysis of concrete structures can be implemented by coupling the finite element and discrete element methods (FEM-DEM). To study the response sensitivities, this paper presents a novel approach by extending the direct differentiation method (DDM) to coupled FEM-DEM multi-scale method. The response and response sensitivity analysis methods are implemented by coupling an existing FEM framework, OpenSees, and DEM software, Yade, based on a client-server (CS) software integration technique. An application example is used to demonstrate the multi-scale response sensitivity method presented herein.

Land-Price Dynamics Surrounding Large-Scale Land Development of Technopolis Gedebage, Bandung, Indonesia

In spite of its potential value to governments, detailed information on how land prices vary spatially in a city is very lacking. Land price in the city, especially around the development activity, is not known. There are some considerable studies showing that investment in land development increases the land market price; however, only a few are found. One of them is about the impact of large-scale investment by Sumarecon in Gedebage Bandung, which is planning to develop “Technopolis”, as the second center of Bandung Municipality.This paper discusses the land-price dynamics around the Technopolis Gedebage Bandung, using information obtained from many sources including an interview with experienced brokers. Appraised prices were given for different types of residential plot distinguished by tenure, distance from the main road, and infrastructural provision. This research aims to explain the dynamics of the land price surrounding the large-scale land development. The dynamics of the land price are described by the median land price market growth using the Surfer DEM software. The data analysis in Technopolis Gedebage Bandung shows the relative importance of land location, infrastructural provision and tenure (land title) for dynamics of the land price. The examination of data makes it possible to test whether and where there has been a spiraling of land prices. This paper argues that the increasing recent price has been consistently greater in suburban plots than that in the inner city as a result of the massive demand of the large-scale land development project. The increasing price of land cannot be controlled; the market price is rising very quickly among other things due to the fact that Gedebage will become the technopolis area. This, however, can indirectly burden the lower-middle-class groups, such as they are displaced from their previous owned-land, and implicate on ever-decreasing income as the livelihood resources (such as farming and agriculture) are lost.