Editing Discrete element method (section)

==The DEM family==
The various branches of the DEM family are the [[distinct element method]] proposed by [[Peter A. Cundall]] and Otto D. L. Strack in 1979,<ref>{{Cite journal|last1=Cundall|first1=Peter. A.|last2=Strack|first2=Otto D. L.|date=1979|title=Discrete numerical model for granular assemblies|url=http://websrv.cs.umt.edu/classes/cs477/images/0/0e/Cundall_Strack.pdf|journal=Géotechnique|volume=29|issue=1|pages=47–65|doi=10.1680/geot.1979.29.1.47}}</ref> the [[generalized discrete element method]],<ref name="WHM85">{{cite journal |last1=Williams |first1=J. R. |last2=Hocking |first2=G. |last3=Mustoe |first3=G. G. W. |title=The Theoretical Basis of the Discrete Element Method |journal=NUMETA 1985, Numerical Methods of Engineering, Theory and Applications |publisher=A.A. Balkema |location=Rotterdam |date=January 1985|url=https://docs.google.com/document/d/1ljujwjib2h2NwYksdh9wONZhEpNljGQdAmehXANFJw4}}</ref> the [[Discontinuous Deformation Analysis|discontinuous deformation analysis]] (DDA) {{harv|Shi|1992}} and the finite-discrete element method concurrently developed by several groups (e.g., [[Ante Munjiza|Munjiza]] and [[Roger Owen (mathematician)|Owen]]). The general method was originally developed by Cundall in 1971 to problems in rock mechanics. 
Williams<ref name="WHM85" /> showed that DEM could be viewed as a generalized finite element method, allowing deformation and fracturing of particles. Its application to geomechanics problems is described in the book ''Numerical Methods in Rock Mechanics''.{{sfn|Williams|Pande|Beer|1990}} The 1st, 2nd and 3rd International Conferences on Discrete Element Methods have been a common point for researchers to publish advances in the method and its applications. Journal articles reviewing the state of the art have been published by Williams and O'Connnor,<ref>{{cite journal |last1=Williams |first1=J. R. |last2=O'Connor |first2=R. |title=Discrete element simulation and the contact problem |journal=Archives of Computational Methods in Engineering |date=December 1999 |volume=6 |issue=4 |pages=279–304 |doi=10.1007/BF02818917|citeseerx=10.1.1.49.9391 |s2cid=16642399 }}</ref> [[Nenad Bicanic|Bicanic]], and [[Antonio Bobet|Bobet]] et al. (see below).  A comprehensive treatment of the combined Finite Element-Discrete Element Method is contained in the book ''The Combined Finite-Discrete Element Method''.<ref name="Munjiza 2004">{{cite book |last1=Munjiza |first1=Ante |title=The Combined Finite-Discrete Element Method |date=2004 |publisher=Wiley |location=Chichester |isbn=978-0-470-84199-0}}</ref>

[[File:Cundall DEM.gif|thumb|upright=1|Discrete-element simulation with particles arranged after a photo of [[Peter A. Cundall]]. As proposed in Cundall and Strack (1979), grains interact with linear-elastic forces and Coulomb friction. Grain kinematics evolve through time by temporal integration of their force and torque balance. The collective behavior is self-organizing with discrete shear zones and angles of repose, as characteristic to cohesionless granular materials.]]