scholarly journals Analysis and Optimization of Material Flow inside the System of Rotary Coolers and Intake Pipeline via Discrete Element Method Modelling

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1849 ◽  
Author(s):  
Jakub Hlosta ◽  
David Žurovec ◽  
Jiří Rozbroj ◽  
Álvaro Ramírez-Gómez ◽  
Jan Nečas ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Material Flow ◽  
Discrete Element ◽  
Operating Conditions ◽  
Particulate Solids ◽  
Cooling Design ◽  
Pipeline Design ◽  
The Given ◽  
Fluidized Bed Boilers ◽  
Element Method

There is hardly any industry that does not use transport, storage, and processing of particulate solids in its production process. In the past, all device designs were based on empirical relationships or the designer’s experience. In the field of particulate solids, however, the discrete element method (DEM) has been increasingly used in recent years. This study shows how this simulation tool can be used in practice. More specifically, in dealing with operating problems with a rotary cooler which ensures the transport and cooling of the hot fly ash generated by combustion in fluidized bed boilers. For the given operating conditions, an analysis of the current cooling design was carried out, consisting of a non-standard intake pipeline, which divides and supplies the material to two rotary coolers. The study revealed shortcomings in both the pipeline design and the cooler design. The material was unevenly dispensed between the two coolers, which combined with the limited transport capacity of the coolers, led to overflowing and congestion of the whole system. Therefore, after visualization of the material flow and export of the necessary data using DEM design measures to mitigate these unwanted phenomena were carried out.

scholarly journals Analysis of particle dynamics in a pin mill by Discrete Element Method

2021 ◽  
Vol 249 ◽  
pp. 07010
Author(s):  
Wei Pin Goh ◽  
Mojtaba Ghadiri
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Particle Dynamics ◽  
Operating Conditions ◽  
Impact Testing ◽  
Process Conditions ◽  
Pharmaceutical Industries ◽  
Element Method

Milling is an important process for tailoring the particle size distribution for enhanced attributes, such as dissolution, content uniformity, tableting, etc., especially for active pharmaceutical ingredients and excipients in pharmaceutical industries. Milling performance of particulate solids depends on the equipment operating conditions (geometry, process conditions and input energy etc.) as well as material properties (particle size, shape, and mechanical properties, such as Young’s modulus, hardness and fracture toughness). In this paper the particle dynamics in a pin mill is analysed using Discrete Element Method (DEM), combined with a novel approach for assessing particle breakability by single particle impact testing. A sensitivity analysis is carried out addressing the effect of the milling conditions (rotational speed and feed particle flow rate), accounting for feed mechanical properties on the breakage behaviour of the particles. Particle collision energy spectra are calculated and shown to have a distribution with the upper tail end being close to the maximum energy associated with the collision with the rings. Breakage is primarily due to collisions with the rings, except for large particles that are comparable in size with the gap between the rings, nipping is also a contributory breakage mechanism.

scholarly journals Discrete Element Method Modeling for the Failure Analysis of Dry Mono-Size Coke Aggregates

2021 ◽  
Author(s):  
Alireza Sadeghi Chahardeh ◽  
Roozbeh Mollaabbasi ◽  
Donald Picard ◽  
Seyed Mohammad Taghavi ◽  
Houshang Alamdari
Keyword(s):  
Discrete Element Method ◽  
Failure Analysis ◽  
Strain Rate ◽  
Confining Pressure ◽  
Discrete Element ◽  
Second Order ◽  
Operating Conditions ◽  
Compaction Process ◽  
Carbon Anodes ◽  
Element Method

An in-depth study of the failure of granular materials, which is known as a mechanism to generate defects, can reveal the facts about the origin of the imperfections such as cracks in the carbon anodes. The initiation and propagation of the cracks in the carbon anode, especially the horizontal cracks below the stub-holes, reduce the anode efficiency during the electrolysis process. In order to avoid the formation of cracks in the carbon anodes, the failure analysis of coke aggregates can be employed to determine the appropriate recipe and operating conditions. In this paper, it will be shown that a particular failure mode can be responsible for the crack generation in the carbon anodes. The second-order work criterion is employed to analyze the failure of the coke aggregate specimens and the relationships between the second-order work, the kinetic energy, and the instability of the granular material are investigated. In addition, the coke aggregates are modeled by exploiting the discrete element method (DEM) to reveal the micro-mechanical behavior of the dry coke aggregates during the compaction process. The optimal number of particles required for the failure analysis in the DEM simulations is determined. The effects of the confining pressure and the strain rate as two important compaction process parameters on the failure are studied. The results reveal that increasing the confining pressure enhances the probability of the diffusing mode of the failure in the specimen. On the other hand, the increase of strain rate augments the chance of the strain localization mode of the failure in the specimen.

Investigation of Turbocharger Dynamics Using a Combined Explicit Finite and Discrete Element Method Rotor–Cartridge Model

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Matthew D. Brouwer ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Discrete Element Method ◽  
Ball Bearing ◽  
Discrete Element ◽  
Operating Conditions ◽  
Test Rig ◽  
Explicit Finite Element ◽  
Critical Speeds ◽  
Bearing Dynamics ◽  
Element Method

The objectives of this investigation were to develop a coupled dynamic model for turbocharger ball bearing rotor systems, correlate the simulated shaft motion with experimental results, and analyze the corresponding bearing dynamics. A high-speed turbocharger test rig was designed and developed in order to measure the dynamic response of a rotor under various operating conditions. Displacement sensors were used to record shaft motion over a range of operating speeds. To achieve the objectives of the analytical investigation, a discrete element angular contact ball bearing cartridge model was coupled with an explicit finite element shaft to simulate the dynamics of the turbocharger test rig. The bearing cartridge consists of a common outer ring, a pair of split inner races, and a row of balls on each end of the cartridge. The dynamic cartridge model utilizes the discrete element method in which each of the bearing components (i.e., races, balls, and cages) has six degrees-of-freedom. The rotor is modeled using the explicit finite element method. The cartridge and rotor models are coupled such that the motion of the flexible rotor is transmitted to the inner races of the cartridge with the corresponding reaction forces and moments from the bearings being applied to the rotor. The coupled rotor–cartridge model was used to investigate the shaft motion and bearing dynamics as the system traverses critical speeds. A comparison of the analytical and experimental shaft motion results resulted in minimal correlation but showed similarity through the critical speeds. The cartridge model allowed for thorough investigation of bearing component dynamics. Effects of ball material properties were found to have a significant impact on turbocharger rotor and bearing dynamics.

A random form generator for ballast stones

2017 ◽  
Vol 232 (6) ◽  
pp. 1660-1670
Author(s):  
Bo Wang ◽  
Ullrich Martin
Keyword(s):  
Discrete Element Method ◽  
Mechanical Behavior ◽  
Discrete Element ◽  
Ballasted Track ◽  
Random Form ◽  
European Standards ◽  
The Given ◽  
Element Method

Ballast form has a critical influence on the mechanical behavior of a ballasted track. To investigate this influence, discrete element method-based simulations are often performed, in which each ballast stone can be depicted differently. To this end, algorithms are often used to capture the form of ballast stones. In this paper, an algorithm-based random form generator for ballast stones is introduced. The generator uses geometrical specifications of ballast stones according to the European standards of ballast aggregations to quantify the form of a single ballast stone, as well as to generate ballast aggregation with the given form parameters. Five aggregations are created to examine the reliability of the generator. The result shows good performance of the generator, especially when a larger aggregation is to be created. The generator can be used for creating ballast aggregations with different form parameters, so that their impact on the mechanical behavior of ballasted tracks can be studied further in discrete element method simulations.

Dynamic modeling of the turning process of slip-cast fused silica ceramics using the discrete element method

2019 ◽  
Vol 234 (3) ◽  
pp. 629-640
Author(s):  
Hossein Roostai ◽  
Mohammad Reza Movahhedy
Keyword(s):  
Discrete Element Method ◽  
Chip Formation ◽  
Cutting Forces ◽  
Discrete Element ◽  
Fused Silica ◽  
Operating Conditions ◽  
Machining Process ◽  
Contact Model ◽  
Slip Cast ◽  
Element Method

Simulation of brittle regime machining of materials (such as ceramics) is often difficult because of the complex material removal mechanisms involved. In this study, the discrete element method is used to simulate the dynamic process for machining of slip-cast fused silica ceramics. Flat-joint contact model is exploited to model contacts between particles in synthetic discrete element method models. This contact model is suitable for modeling of brittle materials with high ratios (higher than 10) of unconfined compressive strength to tensile strength. The discrete element method has the ability to simulate initiation, propagation, and coalescence of cracks leading to chip formation in the brittle regime of cutting. Applying the discrete element method, the influences of operating conditions on the creation of surface/subsurface damages, chip formation, and cutting forces are studied. It is shown that the parameters of the material model determined from conventional calibration tests do not provide quantitatively accurate prediction of cutting forces. As such, model updating is carried out using the forces obtained in the cutting experiments, and the numerical results are verified against experimental cutting forces. The differences between experimental and numerical machining forces are in the range of 10%–30%. Finally, the results of discrete element method simulations reveal that the nature of micro-crack propagation is brittle in the machining process of ceramics.

scholarly journals Discrete Element Method Modeling for the Failure Analysis of Dry Mono-Size Coke Aggregates

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2174
Author(s):  
Alireza Sadeghi-Chahardeh ◽  
Roozbeh Mollaabbasi ◽  
Donald Picard ◽  
Seyed Mohammad Taghavi ◽  
Houshang Alamdari
Keyword(s):  
Discrete Element Method ◽  
Failure Analysis ◽  
Strain Rate ◽  
Confining Pressure ◽  
Discrete Element ◽  
Second Order ◽  
Operating Conditions ◽  
Compaction Process ◽  
Carbon Anodes ◽  
Element Method

An in-depth study of the failure of granular materials, which is known as a mechanism to generate defects, can reveal the facts regarding the origin of the imperfections, such as cracks in the carbon anodes. The initiation and propagation of the cracks in the carbon anode, especially the horizontal cracks below the stub-holes, reduce the anode efficiency during the electrolysis process. The failure analysis of coke aggregates can be employed to determine the appropriate recipe and operating conditions in order to avoid the formation of cracks in the carbon anodes. In this paper, it will be shown that a particular failure mode can be responsible for the crack generation in the carbon anodes. The second-order work criterion is employed to analyze the failure of the coke aggregate specimens and the relationships between the second-order work, the kinetic energy, and the instability of the granular material are investigated. In addition, the coke aggregates are modeled by exploiting the discrete element method (DEM) to reveal the micro-mechanical behavior of the dry coke aggregates during the compaction process. The optimal number of particles required for the failure analysis in the DEM simulations is determined. The effects of the confining pressure and strain rate as two important compaction process parameters on the failure are studied. The results reveal that increasing the confining pressure enhances the probability of the diffusing mode of the failure in the specimen. On the other hand, the increase of strain rate augments the chance of the strain localization mode of the failure in the specimen.

Discrete element method to model cracking for two layer systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Discrete Element Method ◽  
Flexural Modulus ◽  
Single Layer ◽  
Discrete Element ◽  
Flexural Stress ◽  
Layer System ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Layers ◽  
Element Method

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.

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