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DTSTART:19700329T010000
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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Keynote lecture: Some new approaches to obtaining 
 forces in DEM - Ken Kamrin (Massachusetts Institut
 e of Technology)
DTSTART;TZID=Europe/London:20230822T100000
DTEND;TZID=Europe/London:20230822T110000
UID:TALK202573AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/202573
DESCRIPTION:This talk will discuss two new approaches to obtai
 ning contact forces in stiff grain systems. Typica
 l&nbsp\;discrete element methods (DEM) use an elas
 tic contact law to infer interparticle forces thro
 ugh apparent overlaps.&nbsp\; While some practitio
 ners view these overlap forces merely as a penalty
  in order to achieve a desired rigid-grain respons
 e\, these forces actually encompass the mechanics 
 of the grain elasticity and add important physics 
 to the process even for stiff static packings.&nbs
 p\; For example\, without the elastic physics\, ri
 gid-grain models such as contact dynamics (CD) can
  suffer from issues such as force indeterminacy wh
 ich sometimes affects the way the packing flows dy
 namically.&nbsp\;&nbsp\;\nIn the first part of thi
 s talk\, we will discuss a modification to CD for 
 hard grains which still assumes the grains are rig
 id&nbsp\;but guarantees&nbsp\;the forces found by 
 the solver are the ones that are&nbsp\;compatible&
 nbsp\;with a chosen elastic contact law --- that i
 s\, the forces obtained could have come from addin
 g a small displacement to the grains and applying 
 one's desired force model (e.g. Hertz\, Hooke) to 
 the overlaps.&nbsp\; This resolves the indetermina
 cy problem of CD while maintaining the benefits of
  CD such as the larger time-step that CD offers ov
 er DEM.\nIn the second part\, we discuss a new DEM
  contact model for grains made from anisotropic el
 astic material\, such as crystalline solids. The c
 ontact law we obtain is remarkably accurate when c
 ompared with exact finite-element solutions\, for 
 a wide range of materials and surface geometries.&
 nbsp\; We showcase two application examples based 
 on real materials where elastic anisotropy of the 
 particles induces noticeable effects on macroscopi
 c behavior. For example\, we demonstrate the abili
 ty to engineer tunable vibrational band gaps in a 
 stack of grains by merely rotating the constituent
  spherical particles.
LOCATION:External
CONTACT:
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