scholarly journals Computational Coupled Method for Multiscale and Phase Analysis

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Moonho Tak ◽  
Duhee Park ◽  
Taehyo Park
Keyword(s):  
Element Model ◽  
Discrete Element ◽  
Multiscale Methods ◽  
Contact Forces ◽  
Multiscale Approach ◽  
Theoretical Approaches ◽  
Macro Scale ◽  
Coupling Algorithms ◽  
Coupling Algorithm ◽  
Element Method

On micro scale the constitutions of porous media are effected by other constitutions, so their behaviors are very complex and it is hard to derive theoretical formulations as well as to simulate on macro scale. For decades, in order to escape this complication, the phenomenological approaches in a field of multiscale methods have been extensively researched by many material scientists and engineers. Their theoretical approaches are based on the hierarchical multiscale methods using a priori knowledge on a smaller scale; however it has a drawback that an information loss can be occurred. Recently, according to a development of the core technologies of computer, the ways of multiscale are extended to a direct multiscale approach called the concurrent multiscale method. This approach is not necessary to deal with complex mathematical formulations, but it is noted as an important factor: development of computational coupling algorithms between constitutions in a porous medium. In this work, we attempt to develop coupling algorithms in different numerical methods finite element method (FEM), smoothed particle hydrodynamics (SPH) and discrete element method (DEM). Using this coupling algorithm, fluid flow, movement of solid particle, and contact forces between solid domains are computed via proposed discrete element which is based on SPH, FEM, and DEM. In addition, a mixed FEM on continuum level and discrete element model with SPH particles on discontinuum level is introduced, and proposed coupling algorithm is verified through numerical simulation.

scholarly journals Numerical simulation on coal loading process of shearer drum based on discrete element method

2021 ◽  
pp. 014459872110135
Author(s):  
Zhen Tian ◽  
Shuangxi Jing ◽  
Lijuan Zhao ◽  
Wei Liu ◽  
Shan Gao
Keyword(s):  
Numerical Simulation ◽  
Discrete Element Method ◽  
Loading Rate ◽  
Low Cost ◽  
Element Model ◽  
Discrete Element ◽  
Helix Angle ◽  
Loading Process ◽  
Coal Particles ◽  
Element Method

The drum is the working mechanism of the coal shearer, and the coal loading performance of the drum is very important for the efficient and safe production of coal mine. In order to study the coal loading performance of the shearer drum, a discrete element model of coupling the drum and coal wall was established by combining the results of the coal property determination and the discrete element method. The movement of coal particles and the mass distribution in different areas were obtained, and the coal particle velocity and coal loading rate were analyzed under the conditions of different helix angles, rotation speeds, traction speeds and cutting depths. The results show that with the increase of helix angle, the coal loading first increases and then decreases; with the increase of cutting depth and traction speed, the coal loading rate decreases; the increase of rotation speed can improve the coal loading performance of drum to a certain extent. The research results show that the discrete element numerical simulation can accurately reflect the coal loading process of the shearer drum, which provides a more convenient, fast and low-cost method for the structural design of shearer drum and the improvement of coal loading performance.

Recent Developments of the Multiphysics Discrete Element Method for Additive Manufacturing Modeling and Simulation

2017 ◽  
Author(s):  
John C. Steuben ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Additive Manufacturing ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Additive Manufacture ◽  
Computational Tools ◽  
Computational Performance ◽  
Macro Scale ◽  
Recent Developments ◽  
Am Processes ◽  
Element Method

Recent years have seen a sharp increase in the development and usage of Additive Manufacturing (AM) technologies for a broad range of scientific and industrial purposes. The drastic microstructural differences between materials produced via AM and conventional methods has motivated the development of computational tools that model and simulate AM processes in order to facilitate their control for the purpose of optimizing the desired outcomes. This paper discusses recent advances in the continuing development of the Multiphysics Discrete Element Method (MDEM) for the simulation of AM processes. This particle-based method elegantly encapsulates the relevant physics of powder-based AM processes. In particular, the enrichment of the underlying constitutive behaviors to include thermoplasticity is discussed, as are methodologies for modeling the melting and re-solidification of the feedstock materials. Algorithmic improvements that increase computational performance are also discussed. The MDEM is demonstrated to enable the simulation of the additive manufacture of macro-scale components. Concluding remarks are given on the tasks required for the future development of the MDEM, and the topic of experimental validation is also discussed.

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.

scholarly journals A Numerical Study of Railway Ballast Subjected to Direct Shearing Using the Discrete Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Hongyi Zhao ◽  
Jing Chen
Keyword(s):  
Discrete Element Method ◽  
Mechanical Performance ◽  
Numerical Study ◽  
Discrete Element ◽  
Contact Forces ◽  
Angle Of Repose ◽  
Particle Rotation ◽  
Railway Ballast ◽  
Depth Analysis ◽  
Element Method

Railway ballast is a coarse granular material used to carry train loads and provide drainage for the rail tracks. This study presents numerical explorations of the mechanical performance of ballast aggregates subjected to direct shear tests. The discrete element method (DEM) was used to investigate the microscopic characteristics of ballast aggregates during shearing while considering contact distribution, particle rotation, and particle displacement. By testing the angle of repose of ballast aggregates, the parameters for the DEM contact model could be calibrated. Four specimens were prepared and then subjected to different normal pressures. The results show that the contact between ballast particles intensifies in terms of the amount and magnitude as the normal pressure increases. A Fourier analysis was applied to investigate the anisotropy of contact normal and the contact forces for ballast aggregates at different shearing phases. The rotational and translational movements of ballast particles were investigated, and this investigation revealed that particle rotation gradually increased as the shearing propagated. Four regions in the aggregates were identified according to the translational pattern of ballast particles. The results of this research provide an in-depth analysis of microscopic characteristics from a particulate scale.

DISCRETE ELEMENT METHOD FOR MULTISCALE MODELING

2010 ◽  
Vol 02 (01n02) ◽  
pp. 147-162 ◽  
Author(s):  
J. BRUCHMÜLLER ◽  
S. GU ◽  
K. H. LUO ◽  
B. G. M. VAN WACHEM
Keyword(s):  
Discrete Element Method ◽  
Multiscale Modeling ◽  
Fluid Phase ◽  
Discrete Element ◽  
Multiscale Approach ◽  
Coffee Bean ◽  
Transfer Coefficients ◽  
Scale Level ◽  
Scale Levels ◽  
Element Method

A discrete element method (DEM) has been developed to provide highly accurate and detailed predictions of the Lagrangian particle phase. Especially in this study, DEM has been used together with an Eulerian approach for the fluid phase to look at interphase exchange phenomena in a multiphase-multiscale modeling approach. The drying process inside a fluidized bed coffee bean roaster has been chosen. Herein, heat, mass, and momentum transport are solved on a fluid cell level; heat, mass, and momentum transfer coefficients are solved at a particle scale level; and 1D temperature and moisture content profiles are solved inside each coffee bean on a sub-particle scale level. Therefore, this multiscale approach provides much more information compared to existing coffee bean roaster models. In this work, a detailed description of this method is provided and results on different scale levels have been discussed. Modeling data and experimental results are compared and found to be in good agreement.

Coupled Discrete Element/Finite Element Method for the Analysis of Large Reinforced Concrete Structures Submitted to an Impact

2011 ◽  
Vol 82 ◽  
pp. 284-289
Author(s):  
Laurent Daudeville ◽  
Jessica Haelewyn ◽  
Philippe Marin ◽  
Serguei Potapov
Keyword(s):  
Reinforced Concrete ◽  
Finite Elements ◽  
Heterogeneous Media ◽  
Concrete Slab ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Elements ◽  
Reinforced Concrete Slab ◽  
The Impact ◽  
Element Method

The efficiency of the discrete element method for studying the fracture of heterogeneous media has been demonstrated, but it is limited by the size of the computational model. A coupling between the discrete elements (DEM) and the finite elements (FEM) methods is proposed to handle the simulation of impacts on large structures. The structure is split into two subdomains in each of which the method is adapted to the behavior of the structure under impact. The DEM takes naturally into account the discontinuities and is used to model the media in the impact zone. The remaining structure is modeled by the FEM. We propose an adaptation of the coupling procedure to connect Discrete Element model to shell-type Finite Elements. Finally, the efficiency of this approach is shown on the simulation of a reinforced concrete slab impacted by a tubular impactor.

Applicable Contact Force Models for the Discrete Element Method: The Single Particle Perspective

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
H. Kruggel-Emden ◽  
S. Wirtz ◽  
V. Scherer
Keyword(s):  
Discrete Element Method ◽  
Granular Materials ◽  
Experimental Studies ◽  
Spherical Shape ◽  
Discrete Element ◽  
Industrial Applications ◽  
Contact Forces ◽  
Experimental Investigations ◽  
Simulation Techniques ◽  
Element Method

Several processes in nature as well as many industrial applications involve static or dynamic granular materials. Granulates can adopt solid-, liquid-, or gaslike states and thereby reveal intriguing physical phenomena not observable in its versatility for any other form of matter. The frequent occurrence of phase transitions and the related characteristics thereby strongly affect their processing quality and economics. This situation demands for prediction methods for the behavior of granulates. In this context simulations provide a feasible alternative to experimental investigations. Several different simulation approaches are applicable to granular materials. The time-driven discrete element method turns out to be not only the most complex but also the most general simulation approach. Discrete element simulations have been used in a wide variety of scientific fields for more than 30 years. With the tremendous increase in available computer power, especially in the past years, the method is more and more developing to the state of the art simulation technique for granular materials not only in science but also in industrial applications. Several commercial software packages utilizing the time-driven discrete element method have emerged and are becoming more and more popular within the engineering community. Despite the long time of usage of the time-driven discrete element method, model advances derived and theoretical and experimental studies performed in the different branches of application lack harmonization. They thereby provide potential for improvements. Therefore, the scope of this paper is a review of methods and models for contact forces based on theoretical considerations and experimental data from literature. Particles considered are of spherical shape. Through model advances it is intended to contribute to a general enhancement of simulation techniques, which help improve products and the design of the related equipment.

Modeling of Granular Flow and Combined Heat Transfer in Hoppers by the Discrete Element Method (DEM)

2005 ◽  
Vol 128 (3) ◽  
pp. 439-444 ◽  
Author(s):  
Harald Kruggel-Emden ◽  
Siegmar Wirtz ◽  
Erdem Simsek ◽  
Viktor Scherer
Keyword(s):  
Discrete Element Method ◽  
Heat Transport ◽  
Granular Flow ◽  
Granular Media ◽  
Element Model ◽  
Discrete Element ◽  
Waste Utilization ◽  
Discrete Element Modeling ◽  
Particle Assemblies ◽  
Element Method

The discrete element method can be used for modeling moving granular media in which heat and mass transport takes place. In this paper the concept of discrete element modeling with special emphasis on applicable force laws is introduced and the necessary equations for heat transport within particle assemblies are derived. Possible flow regimes in moving granular media are discussed. The developed discrete element model is applied to a new staged reforming process for biomass and waste utilization which employs a solid heat carrier. Results are presented for the flow regime and heat transport in substantial vessels of the process.

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