Compaction simulation

Compaction simulation

Compaction simulation is the modelling of granular matter is compressed into a dense state that is achieved through the reduction of the air void.

Three stages are included in the compaction process those are filling or packing, compaction and ejection. During the compaction process, if the loading pressure is increasing straightly, the powder assembly will experience three stages. First of all, particles are filling the voids and set up contacts with the adjacent particles. This stage is termed rearrangement stage. After most contacts are set up, the initial compaction started. Elastic deformation and plastic deformation happens and the loading pressure increases sharply. The third stage is breakage where the particles breaks into fragments.

Discrete Element Method (DEM) is an explicit numerical model capable of tracking the motion and interaction of individual modeled particles[1]. DEM has enhanced rapidly our understanding of granular system by producing quantitative predictions rather than only qualitative description, increased our insight into particle assemblies by providing both microscopic and macroscopic information[2][3]. DEM has been proved to be of great potential in scientific tasks and industries[4][5], including chemical and mechanical engineering, food industry, geo-sciences and agriculture.

The translational and rotational movement of each particle can be calculated by Newton’s second law of motion. Forces involved are normally particle gravity and inter-particle contact forces including normal and tangential force. Other forces are van der Waals force and capillary force for fine and wet particles system respectively.

The whole simulation process includes compaction and breakage, involves four stages: packing, compaction, relaxation and crushing. At the beginning of packing stage, modeled particles were generated randomly in a square space and allowed to fall under gravity with a small initial velocity to form a packing. There are no overlaps between the particles, and the walls. Then the packing bed is compressed by a modeled plane at a low speed, most of the time, it is set to 10d/s. When the compact density reaches the set value, for example 0.75, the loading process stops and the plane goes up with the speed 5d/s. The compaction stage is ended when the top plane leaves the highest particle. In the recently research, periodical boundaries are used during the packing and compaction stages to exclude the effect of wall.

References

  1. ^ Cundall, P.A. and O.D.L. Strack, Discrete Numerical-Model for Granular Assemblies. Geotechnique, 1979. 29(1): p. 47-65.
  2. ^ H. J. Herrmann, J.-P.H., and S. Luding., Physics of dry granular media - NATO ASI Series E 350. 1998, Dordrecht: Kluwer Acad. Publ.
  3. ^ P. A. Vermeer, S.D., W. Ehlers, H. J. Herrmann, S. Luding, and E. Ramm., Continuous and Discontinuous Modelling of Cohesive Frictional Materials. 2001, Berlin: Springer.
  4. ^ Oda, M. and H. Kazama, Microstructure of shear bands and its relation to the mechanisms of dilatancy and failure of dense granular soils. Geotechnique, 1998. 48(4): p. 465-481.
  5. ^ Thornton, C., Numerical simulations of deviatoric shear deformation of granular media. Geotechnique, 2000. 50(1): p. 43-53.

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Discrete element method — A discrete element method (DEM), also called a distinct element method is any of family of numerical methods for computing the motion of a large number of particles of micrometre scale size and above. Though DEM is very closely related to… …   Wikipedia

  • rock — rock1 rockless, adj. rocklike, adj. /rok/, n. 1. a large mass of stone forming a hill, cliff, promontory, or the like. 2. Geol. a. mineral matter of variable composition, consolidated or unconsolidated, assembled in masses or considerable… …   Universalium

  • Rock — /rok/, n. a male given name. * * * I In geology, a naturally occurring and coherent aggregate of minerals. The three major classes of rock igneous, sedimentary, and metamorphic are based on the processes that formed them. These three classes are… …   Universalium

  • MODFLOW — simulation MODFLOW is the U.S. Geological Survey modular finite difference flow model, which is a computer code that solves the groundwater flow equation. The program is used by hydrogeologists to simulate the flow of groundwater through aquifers …   Wikipedia

  • режим — 36. режим [частота вращения] «самоходности»: Режим [минимальная частота вращения выходного вала], при котором газотурбинный двигатель работает без использования мощности пускового устройства при наиболее неблагоприятных внешних условиях. Источник …   Словарь-справочник терминов нормативно-технической документации

  • Material Point Method — The Material Point Method (MPM), is an extension of the Particle in cell (PIC) Method in computational fluid dynamics to computational solid dynamics, and is a Finite element method (FEM) based particle method. It is primarily used for multiphase …   Wikipedia

  • Impact crater — The prominent impact crater Tycho on the Moon. In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body. In most common usage,… …   Wikipedia

  • Landslide — This article is about the geological phenomenon. For other uses, see Landslide (disambiguation). Rockslide redirects here. For the comic book character, see Rockslide (comics). Computer simulation of a slump landslide in San Mateo County,… …   Wikipedia

  • Subnivean climate — ubnivean ClimateSubnivean Climate refers to the zone in and underneath the snow pack. This is the environment of many animals that remain active during the winter. This zone provides protection from predators and insulation from the elements. The …   Wikipedia

  • Wildfire — This article is about uncontrolled outdoor fire. For the New York rock band, see Forest Fire (band). For other uses, see Wildfire (disambiguation). Crown Fire redirects here. For the 2010 wildfire in Southern California, see 2010 California… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”