Multi-Scale Simulations of Rearrangement Effects and Anisotropic Behaviour during Sintering

2006 ◽  
Vol 45 ◽  
pp. 530-538 ◽  
Author(s):  
Andreas Wonisch ◽  
Torsten Kraft ◽  
Hermann Riedel
Keyword(s):  
Numerical Modeling ◽  
Discrete Element Method ◽  
Crack Formation ◽  
Industrial Applications ◽  
Sintering Process ◽  
Densification Rate ◽  
Mesoscopic Scale ◽  
Multi Scale ◽  
Open Questions ◽  
Mechanical Models

Numerical modeling of sintering by continuum mechanical simulations is successfully applied today to predict e.g. the distortions developing during sintering. Several examples that demonstrate the possibilities of such simulations especially for industrial applications have been published recently. However, there are still open questions regarding the influence of grain rearrangement, crack formation and anisotropic starting configurations (e.g. due to prior compaction). By using the Discrete Element Method the sintering process can be investigated on a more fundamental mesoscopic scale. This method also considers effects due to particle rearrangement or anisotropic configurations as well as crack developments automatically. Their influence on various macroscopic properties like densification rate and viscosities is studied. Suggestions how to use these insights to improve existing continuum mechanical models are given.

scholarly journals Numerical Modeling of a Punch Penetration Test Using the Discrete Element Method

2020 ◽  
Vol 28 (2) ◽  
pp. 1-7
Author(s):  
Rouhollah Basirat ◽  
Jafar Khademi Hamidi
Keyword(s):  
Numerical Modeling ◽  
Discrete Element Method ◽  
Numerical Models ◽  
Confining Pressure ◽  
Discrete Element ◽  
Numerical Results ◽  
Strength Parameter ◽  
Penetration Test ◽  
Strength Parameters ◽  
Element Method

AbstractUnderstanding the brittleness of rock has a crucial importance in rock engineering applications such as the mechanical excavation of rock. In this study, numerical modeling of a punch penetration test is performed using the Discrete Element Method (DEM). The Peak Strength Index (PSI) as a function of the brittleness index was calculated using the axial load and a penetration graph obtained from numerical models. In the first step, the numerical model was verified by experimental results. The results obtained from the numerical modeling showed a good agreement with those obtained from the experimental tests. The propagation path was also simulated using Voronoi meshing. The fracture was created under the indenter in the first step, and then radial fractures were propagated. The effects of confining pressure and strength parameters on the PSI were subsequently investigated. The numerical results showed that the PSI increases with enhancing the confining pressure and the strength parameter of the rock, including cohesion and the friction angle. A new relationship between the strength parameters and PSI was also introduced based on two variable regressions of the numerical results.

Physical Modeling for Selective Laser Sintering Process

2017 ◽  
Vol 17 (2) ◽  
Author(s):  
Arash Gobal ◽  
Bahram Ravani
Keyword(s):  
Physical Modeling ◽  
Large Scale ◽  
Selective Laser Sintering ◽  
Powdered Material ◽  
Laser Sintering ◽  
Industrial Applications ◽  
Transient Temperature ◽  
Sintering Process ◽  
Powder Bed ◽  
Selective Heating

The process of selective laser sintering (SLS) involves selective heating and fusion of powdered material using a moving laser beam. Because of its complicated manufacturing process, physical modeling of the transformation from powder to final product in the SLS process is currently a challenge. Existing simulations of transient temperatures during this process are performed either using finite-element (FE) or discrete-element (DE) methods which are either inaccurate in representing the heat-affected zone (HAZ) or computationally expensive to be practical in large-scale industrial applications. In this work, a new computational model for physical modeling of the transient temperature of the powder bed during the SLS process is developed that combines the FE and the DE methods and accounts for the dynamic changes of particle contact areas in the HAZ. The results show significant improvements in computational efficiency over traditional DE simulations while maintaining the same level of accuracy.

scholarly journals Numerical Modeling of Viscoelasticity in Particle Suspensions Using the Discrete Element Method

Langmuir ◽  
2019 ◽  
Vol 35 (39) ◽  
pp. 12754-12764 ◽  
Author(s):  
Alexandr Zubov ◽  
José Francisco Wilson ◽  
Martin Kroupa ◽  
Miroslav Šoóš ◽  
Juraj Kosek
Keyword(s):  
Numerical Modeling ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Particle Suspensions ◽  
Element Method

Passive Multi-Scale Alignment

2011 ◽  
Author(s):  
David O. Kazmer ◽  
Stephen P. Johnston ◽  
Mary E. Moriarty ◽  
Christopher Santeufemio
Keyword(s):  
Numerical Modeling ◽  
Ion Beam ◽  
Systematic Errors ◽  
Imprint Lithography ◽  
Physical Realization ◽  
Length Scales ◽  
Ion Beam Etching ◽  
Multi Scale ◽  
Kinematic Coupling ◽  
Multiple Length Scales

Methods are presented for self-alignment and assembly of objects with micron and nanometer-level features. The approach is a combination of kinematic coupling and elastic averaging in which mating alignment features spanning multiple length scales are successively brought into contact. When the objects are pressed together, the larger alignment features cause necessary deformation to ensure adequate alignment at the smaller length scales. Analytical and numerical modeling indicate that the largest alignment features can be designed to generally resolve global systematic errors while the smaller alignment features can correct local errors to achieve sub-micron alignment. Physical realization with ion beam etching, deposition, and thermal imprint lithography are also discussed.

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