scholarly journals Discrete Element Method Analysis of the Spreading Mechanism and Its Influence on Powder Bed Characteristics in Additive Manufacturing

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 392
Author(s):  
Valerio Lampitella ◽  
Marco Trofa ◽  
Antonello Astarita ◽  
Gaetano D’Avino
Keyword(s):  
Additive Manufacturing ◽  
Discrete Element Method ◽  
Ad Hoc ◽  
Low Cost ◽  
Discrete Element ◽  
Spreading Process ◽  
Powder Bed ◽  
Physical Phenomena ◽  
Element Method

Laser powder bed fusion additive manufacturing is among the most used industrial processes, allowing for the production of customizable and geometrically complex parts at relatively low cost. Although different aspects of the powder spreading process have been investigated, questions remain on the process repeatability on the actual beam–powder bed interaction. Given the influence of the formed bed on the quality of the final part, understanding the spreading mechanism is crucial for process optimization. In this work, a Discrete Element Method (DEM) model of the spreading process is adopted to investigate the spreading process and underline the physical phenomena occurring. With parameters validated through ad hoc experiments, two spreading velocities, accounting for two different flow regimes, are simulated. The powder distribution in both the accumulation and deposition zone is investigated. Attention is placed on how density, effective layer thickness, and particle size distribution vary throughout the powder bed. The physical mechanism leading to the observed characteristics is discussed, effectively defining the window for the process parameters.

Characterization of powder bed generation in electron beam additive manufacturing by discrete element method (DEM)

2017 ◽  
Vol 4 (11) ◽  
pp. 11437-11440 ◽  
Author(s):  
Yufan Zhao ◽  
Yuichiro Koizumi ◽  
Kenta Aoyagi ◽  
Kenta Yamanaka ◽  
Akihiko Chiba
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Powder Bed ◽  
Element Method

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.

scholarly journals Application of the Discrete Element Method to Study the Effects of Stream Characteristics on Screening Performance

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 788 ◽  
Author(s):  
Ali Davoodi ◽  
Gauti Asbjörnsson ◽  
Erik Hulthén ◽  
Magnus Evertsson
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Relative Difference ◽  
Screening Process ◽  
Material Density ◽  
Screening Performance ◽  
Crushing Plant ◽  
Individual Particles ◽  
Element Method

Screening is a key operation in a crushing plant that ensures adequate product quality of aggregates in mineral processing. The screening process can be divided into the two sub-processes of stratification and passage. The stratification process is affected by the relative difference between various properties, such as particle shape, size distribution, and material density. The discrete element method (DEM) is a suitable method for analyzing the interactions between individual particles and between particles and a screen deck in a controlled environment. The main benefit of using the DEM for simulating the screening process is that this method enables the tracking of individual particles in the material flow, and all of the collisions between particles and between particles and boundaries. This paper presents how different particle densities and flowrates affect material stratification and, in turn, the screening performance. The results of this study show that higher density particles have a higher probability of passage because of their higher stratification rate, which increases the probability that a particle will contact the screen deck during the process.

Random Adjusted Calculation Method for 3D Aggregate of Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 13-16
Author(s):  
Yin Xu ◽  
Sheng Hong Chen
Keyword(s):  
Discrete Element Method ◽  
Calculation Method ◽  
Discrete Element ◽  
New Method ◽  
Computational Time ◽  
Concrete Aggregate ◽  
Analysis Tool ◽  
Advantages And Disadvantages ◽  
Element Method

Discrete element method is emerging as a useful numerical analysis tool for engineers interested in granular materials such as soil, concrete, or pharmaceutical powders. Simulated the concrete’s microscopic property and its impact on the macroscopic property by using particle discrete element method is one of the important research topics. Obviously, the first step in a discrete element simulation is the generation of the geometry of the system concerned, the quality of which will directly decide the quality of the simulation result. An integrated approach termed random adjusted calculation method is proposed in this paper after detailed analysis of the advantages and disadvantages of the existing aggregate delivery methods. The new method is a method which combined both the advantages of random method and non-geometry methods, such as hopper method and explosive repulsion method. Through out the analysis of the basic process of aggregate delivery and indicated by the result of the examples, random adjusted calculation method has the advantages of good overall density and easily controlled grading; and the computational time is smaller than the existing methods of non-geometry aggregate delivery; furthermore, the new method is easily carried out and provides a new idea for the delivery of concrete aggregate.

Selection of Optimal Models for the Discrete Element Method: The Single Particle Perspective

2008 ◽  
Author(s):  
Harald Kruggel-Emden ◽  
Siegmar Wirtz ◽  
Viktor Scherer
Keyword(s):  
Discrete Element Method ◽  
Granular Materials ◽  
Experimental Studies ◽  
Discrete Element ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Long Time ◽  
Feasible Alternative ◽  
Physical Phenomena ◽  
Element Method

Several processes in nature as well as many industrial applications involve static or dynamic granular materials. Granulates can adopt solid, liquid or gas like 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 the most complex but also as the most general method. The method has been used in a wide variety of scientific fields for more than thirty years. With the tremendous increase in available computer power, especially in the last years, the method is more and more developing to the state of the art simulation technique for granular materials. Despite of the long time of usage, model advances and theoretical and experimental studies are not harmonized in the different branches of application, providing potential for improvements. Therefore, the scope of this paper is a review of methods and models based on theoretical considerations and experimental data from literature. Through model advances it is intended to contribute to a general enhancement of techniques, which are then directly available for simulations.

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