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Topic: Discrete element method

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	Discrete element method - Wikipedia, the free encyclopedia
		The theoretical basis of the method was detailed by Williams, Hocking, and Mustoe in 1985 who showed that DEM could be viewed as a generalized finite element method.
		The various branches of the DEM family are the distinct element method proposed by Cundall in 1971, the generalized discrete element method proposed by Hocking, Williams and Mustoe in 1985, the discontinuous deformation analysis (DDA) proposed by Shi in 1988 and the finite-discrete element method proposed by Munjiza and Owen in 2004.
		Discrete element methods are processor intensive and this limits either the length of a simulation or the number of particles.
	en.wikipedia.org /wiki/Discrete_element_method (1077 words)

	Finite element method - Wikipedia, the free encyclopedia
		The method was provided with a rigorous mathematical foundation in 1973 with the publication of Strang and Fix's An Analysis of The Finite Element Method, and has since been generalized into a branch of applied mathematics for numerical modeling of physical systems in a wide variety of engineering disciplines, e.g., electromagnetics and fluid dynamics.
		The development of the finite element method in structural mechanics is often based on an energy principle, e.g., the virtual work principle or the minimum total potential energy principle, which provides a general, intuitive and physical basis that has a great appeal to structural engineers.
		Methods that use higher degree piecewise polynomial basis functions are often called spectral element methods, especially if the degree of the polynomials increases as the triangulation size h goes to zero.
	en.wikipedia.org /wiki/Finite_element_method (2147 words)

	Doctoral research pr The Discrete Element Method (DEM) to simulate fruit impact d ... (Site not responding. Last check: 2007-10-09)
		DEM is essentially a numerical technique to model the kinematic and dynamic behaviour of particles interacting with each other through collisions.
		In DEM the forces acting on the particles (gravity force and contact force) are summed and the equations of motion of Newton and Euler are integrated to obtain the velocity and position of the particles in the next time step.
		DEM originated in the field of rock mechanics and has been used extensively for engineering materials, but its application for biological materials is limited, especially for ‘soft’ biological materials like fruits.
	www.kuleuven.ac.be /research/researchdatabase/project/3E04/3E041124.htm (884 words)

	Show ETD
		The discrete-element method for predicting skin friction for turbulent flow over rough surfaces considers the drag on the surface to be the sum of the skin friction on the flat part of the surface and the drag on the individual roughness elements that protrude into the boundary layer.
		The discrete-element method considers heat transfer from a rough surface to be the sum of convection through the fluid on the flat part of the surface and the convection from each of the roughness elements.
		A method for using the three-dimensional profilometer output to determine the geometry input required in the discrete-element method for randomly-rough surfaces is presented.
	library.msstate.edu /etd/show.asp?etd=etd-04032002-140007 (369 words)

	Discrete Element Method..., Part3 (Site not responding. Last check: 2007-10-09)
		The discrete bounding hull of a sphere represented in this manner is shown in Figure 2.
		The first element of the ORL pair is the offset in cell units to the first slice of the DBH from the origin of the discrete coordinate system.
		Each element of the array is indexed by the offset in cell units to the current slice and prism.
	www.ejge.com /1996/Ppr9603/Part3.htm (1459 words)

	CASA - DEM Simulations of toner behavior in the development nip of the Océ Direct Imaging print process
		The use of the Galerkin finite element method to solve the Laplace equation for the field distribution (with the appropriate re-meshing) at every time step is computationally not achievable in a DEM simulation.
		Thus, a general numerical method has been constructed that for dilute systems, in which the convergence of the local problems is more or less independent of the other local solutions, is computationally efficient and that is able to calculate electric forces in DEM simulations accurately.
		The discrete element method has been used for simulating the behavior of the DI toner assembly in the development nip of the andeacute; Direct Imaging print process.
	www.win.tue.nl /casa/research/casaprojects/severens.html (2338 words)

	Discrete Element Modeling
		A discrete element algorithm is a numerical technique which solves engineering problems that are modeled as a large system of distinct interacting general shaped (deformable or rigid) bodies or particles that are subject to gross motion.
		The discrete element procedure is used to determine the dynamic contact topology of the bodies.
		The animation illustrates a DEM simulation of a flexible highway rockfall prevention fence (developed by the Colorado Department of Highways) being impacted by a 1 ton rock moving at 40 mph.
	egweb.mines.edu /dem (363 words)

	Slide 1
		Discrete Element Models (DEM) of rock are popular tools for extending laboratory observations to make inferences on the micromechanics of granular materials and consolidated rock (Boutt and McPherson, In Press).
		Clusters in DEM models are groups of particles bonded together with higher strength bonds in the cluster than between clusters.
		A new method was necessary to isolate the effects of particle shapes and to reduce the the effects of a distribution of particle cluster sizes
	www.ees.nmt.edu /Hydro/Students/Daveb/agu_2001_poster6_long_files/slide0001.htm (1255 words)

	IStructE - The Institution of Structural Engineers
		Chapter 5 is devoted to the dynamics of irregular discrete elements.
		The author is emphatic on these known methods as an alternative for the determination of amplification factors and periodic error.
		The combined finite-discrete element method is in it's embryonic stage and requires further research and development in order to compete with the existing voluminous FORTRAN packages in the market in which billions have been spent already.
	www.istructe.org.uk /library/DB/474.asp (479 words)

	Finite element method Article, Finiteelementmethod Information (Site not responding. Last check: 2007-10-09)
		The method was introduced by Richard Courant to model the effectof torsion on the shape of a cylinder.
		Development of the method began in earnest in the middle to late 1950s forairframe and structural analysis, and picked up a lot of steam at Berkeley in the 1960s for use in civil engineering.
		Typically,in the finite element method, the set F is chosen directly, and is not usually construed to be a subset of some E. Instead, the functions of F can be chosen to be piecewiselinear.
	www.anoca.org /functions/problem/finite_element_method.html (1533 words)

	Discrete Element Method..., Part4 (Site not responding. Last check: 2007-10-09)
		Discrete modeling of stress-strain behavior of granular media at samll and large strains.
		A dem of cliff collapse and debris flow.
		In Proceedings of the 1st U.S. Conference on Discrete Element Methods (DEM), 1989.
	www.ejge.com /1996/Ppr9603/Part4.htm (475 words)

	Colorado School of Mines Chose ALGOR Software for Explosives Research
		According to Petr, the primary advantage of the DEM software, which was developed by Dr. Graham Mustoe of CSM's Division of Engineering, was that it modeled the geomedium as a system of several hundred rigid particles joined together elastically.
		In the finite element model, initiation of the shock wave was simulated by impacting the top surface of the specimen with a block moving at the same velocity as was measured in the physical experiment.
		CSM's ALGOR finite element model simulated the grain lattice that is typical of a hard rock mass.
	www.algor.com /news_pub/cust_app/Colorado_Mines (1585 words)

	Laboratory for Agricultural Machinery and Processing (Site not responding. Last check: 2007-10-09)
		Van Zeebroeck (2005) The Discrete Element Method (DEM) to simulate fruit impact damage during transport and handling.
		DEM simulations of a one-particle trajectory on a centrifugal fertilizer spreader.
		Loodts, Jimmy: "The discrete element method for the simulation of granular flows".
	www.agr.kuleuven.ac.be /aee/amc/research/dem/publications (1235 words)

	Mathematics of Computation
		The cruxes of the analysis are to establish stability estimates for the discrete solutions, to use a spectrum estimate result of Chen, and to establish a discrete counterpart of it for a linearized phase field operator to handle the nonlinear effect.
		Finally, as a nontrivial byproduct, the error estimates are used to establish convergence of the solution of the fully discrete scheme to solutions of the sharp interface limits of the phase field model under different scaling in its coefficients.
		Analysis of a fully discrete finite element method for the phase field model and approximation of its sharp interphase limits.
	www.ams.org /mcom/2004-73-246/S0025-5718-03-01588-6/home.html (715 words)

	Discrete element method: Facts and details from Encyclopedia Topic (Site not responding. Last check: 2007-10-09)
		Discrete element methods (DEM) comprise a family of related mathematical tools for determining the kinematic Kinematics quick summary:
		In physics, kinematics is the branch of mechanics concerned with the motions of objects without being concerned with the forces that cause the motion....
		Two prominent members of the DEM family are the distinct element method
	www.absoluteastronomy.com /encyclopedia/d/di/discrete_element_method.htm (561 words)

	CFD with discrete element modeling capabilities: News from DEM Solutions
		The result of 10 years R and D, the DEM Solutions EDEM software enables engineers across a broad spectrum of industries - chemical, pharmaceutical, materials processing, mining, and agriculture - to simulate and analyse the behaviour of particulate matter (pills, pellets, aggregates etc) during processing, manufacturing and material handling operations.
		DEM Solutions estimate that the market for discrete element modeling software will grow to be a US$75 million sector worldwide over the next five years.
		John Favier, CEO of DEM Solutions, notes, 'We are delighted to be formalising the relationship with Fluent into a development partnership.
	www.processingtalk.com /news/dem/dem102.html (462 words)

	Discrete Element Method Software Donzé Frédéric Victor Research Projects
		Any element within an interaction range of another element defined as a radius around this element will be interacting with the latter.
		The interactions are known as "soft sphere" interactions because the interaction forces are linked to the displacements of the elements which implies that the elements may penetrate or overlap one another.
		Newton's second law of motion describes the motion of each element as the sum of all forces applied on this element.The dynamic behavior of the system is solved numerically by a time algorithm in which the velocities and the accelerations are constant at each time step.
	geo.hmg.inpg.fr /frederic/Research_project_Discrete_Element_Software.html (298 words)

	Journal of Modeling, Design and Management of Engineering Systems - Vol. 2, No. 1 (2003)
		Discrete element modelling is a numerical method capable of tracking the movement of individual objects within a bulk system and compute the resulting force and deformation as well as other parameters.
		The Discrete Element Method (DEM) has been used in this study to investigate the deformation of individual particles modelled as spherical objects with equivalent properties, porosity and other physical properties of the bulk system as well as other physical parameters during particle interaction within a bulk system subjected to a monotonic compressive load.
		Having developed and validated a code based on the Discrete Element Method principle with physical experiments the code was used to study and predict the behaviour (parametric changes) during compression of four bulk systems of particulates with the properties of canola seed, palm kernel and soyabean.
	www.ajol.info /viewarticle.php?id=13295 (333 words)

	Modelling of Granular Materials Using the Discrete Element Method (Site not responding. Last check: 2007-10-09)
		With the Discrete Element method it is possible to model materials that consists of individual particles where a particle may roll or slide on other particles.
		One on a small sample of angular elements subjected to a pulsating (repeated) biaxial loading and another of a larger sample of circular elements subjected to a plate load.
		At high deviator stresses the stiffness of the assembly of elements was less than one percent of the stiffness of the elements.
	www.asphalt.org /Pubs/8thAbstracts/08046.html (286 words)

	Nat' Academies Press, Stability, Failure, and Measurements of Boreholes and Other Circular Openings (1993)
		Applications of the discrete element method to slope stability (steeply dipping foliation planes) and mining problems are found in Cundall (1987) and Lorig et al.
		(1989); applications of the discrete element method to the collapse of a soil embankment, and penetration of a projectile into a soil can be found in Williams (1987).
		Alternative methods that are between the conventional continuum theory and the detailed discrete methods are therefore desirable.
	www.nap.edu /books/NI000063/html/71.html (572 words)

	Discrete Element Modeling - Snow
		The DEM technique is a logical tool to use to simulate snow because, in addition to employing the grain-scale process models, it has an explicit geometric structure that is composed of individual ice grains and grain clusters and that evolves with deformation and metamorphosis.
		The DEM model snow consists of a large assembly of grains with an arbitrary mixture of axisymmetric particle shapes, including spheres, tapered cylinders, and elongated or oblate spheroids and ellipsoids.
		His research is focused on the development of discrete element modeling techniques and the application of those techniques to simulate problems in sea ice, river ice, and snow mechanics.
	www.crrel.usace.army.mil /sid/hopkins_files/Snow/snow1.htm (1233 words)

	Discrete Element Method (Site not responding. Last check: 2007-10-09)
		The discrete element method (DEM) is a finite difference scheme.
		PENC - 2-D DEM for penetration process (1) (2) of concrete target and a rigid ogive shape penetrator.
		ELLIPSE3 - 3-D DEM for ellipsoids (with periodic space or rigid boundary); it can also perform direct shear test, or simple shear test in addition to triaxial test.
	geolab.unm.edu /dem.html (135 words)

	The Combined Finite-Discrete Element Method (Site not responding. Last check: 2007-10-09)
		Book Description: The combined finite discrete element method is a relatively new computational tool aimed at problems involving static and / or dynamic behaviour of systems involving a large number of solid deformable bodies.
		The combined finite-discrete element method - a natural extension of both discrete and finite element methods - allows researchers to model problems involving the deformability of either one solid body, a large number of bodies, or a solid body which fragments (e.g.
		Download Description: "The combined finite discrete element method is a relatively new computational tool aimed at problems involving static and / or dynamic behaviour of systems involving a large number of solid deformable bodies.
	isbn.nu /0470841990 (636 words)

	Imaging On-Line Store
		As a method for calculating particle motion, DEM(Discrete Element Method) has been attracting a great attention in various fields related to powder and particles.
		In DEM motion of individual particles is calculated by using the Newton’s equations of motion.
		DEM was applied in this work to study motion of carriers in a screw feeder.
	www.imaging.org /store/epub.cfm?abstrid=851 (264 words)

	Analysis and Implementation of the Discrete Element Method Using a Dedicated Highly Parallel Architecture in ... (Site not responding. Last check: 2007-10-09)
		The Discrete Element Method (DEM) is a numerical model to describe the mechanical behaviour of discontinuous bodies.
		The DEM is very computationally expensive, but has properties that make it amenable to acceleration by reconfigurable computing.
		This paper describes the implementation of a dedicated hardware architecture for the DEM implemented on an FPGA, which is capable of giving a speed-up of about 30 times compared to an optimised software version running on a fast microprocessor.
	csdl.computer.org /comp/proceedings/fccm/2002/1801/00/18010173abs.htm (211 words)

	Simulation of Borehole Failure Phenomena using Discrete Element Modeling (Site not responding. Last check: 2007-10-09)
		Radially graded, two-dimensional DEM models of the near-wellbore region were created of bonded disk elements.
		Inspired by the molecular model of a fluid, source elements were used to simulate fluid pressurization of the model borehole subjected to far-field stresses.
		The structural damage in the DEM models was analyzed using histograms of the angular distribution of bond damage; results obtained for various stress states showed qualitative reproduction of the gross failure mechanisms associated with both hydraulic fracturing and borehole breakouts.
	www.sandia.gov /eesector/gs/gm/project_dem.htm (238 words)

	Dynamic properties and liquefaction behaviour of granular materials using discrete element methodePrints@IISc - Open ...
		Dinesh, SV and Sitharam, TG and Vinod, JS (2004) Dynamic properties and liquefaction behaviour of granular materials using discrete element method.
		In this paper, the results of the numerical simulation of cyclic triaxial shear tests on three-dimensional assembly consisting of 1000 sphere particles using Discrete Element Method (DEM) have been reported under undrained conditions.
		The DEM simulations have modeled the liquefaction behaviour under undrained conditions very close to the real experimental behaviour.
	eprints.iisc.ernet.in /archive/00002716 (212 words)

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