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SUMMARY:Keynote lecture: Some new approaches to obtaining forces in DEM - 
 Ken Kamrin (Massachusetts Institute of Technology)
DTSTART:20230822T090000Z
DTEND:20230822T100000Z
UID:TALK202573@talks.cam.ac.uk
DESCRIPTION:This talk will discuss two new approaches to obtaining contact
  forces in stiff grain systems. Typical&nbsp\;discrete element methods (DE
 M) use an elastic contact law to infer interparticle forces through appare
 nt overlaps.&nbsp\; While some practitioners view these overlap forces mer
 ely as a penalty in order to achieve a desired rigid-grain response\, thes
 e forces actually encompass the mechanics of the grain elasticity and add 
 important physics to the process even for stiff static packings.&nbsp\; Fo
 r example\, without the elastic physics\, rigid-grain models such as conta
 ct dynamics (CD) can suffer from issues such as force indeterminacy which 
 sometimes affects the way the packing flows dynamically.&nbsp\;&nbsp\;\nIn
  the first part of this talk\, we will discuss a modification to CD for ha
 rd grains which still assumes the grains are rigid&nbsp\;but guarantees&nb
 sp\;the forces found by the solver are the ones that are&nbsp\;compatible&
 nbsp\;with a chosen elastic contact law --- that is\, the forces obtained 
 could have come from adding a small displacement to the grains and applyin
 g one's desired force model (e.g. Hertz\, Hooke) to the overlaps.&nbsp\; T
 his resolves the indeterminacy problem of CD while maintaining the benefit
 s of CD such as the larger time-step that CD offers over DEM.\nIn the seco
 nd part\, we discuss a new DEM contact model for grains made from anisotro
 pic elastic material\, such as crystalline solids. The contact law we obta
 in is remarkably accurate when compared with exact finite-element solution
 s\, for a wide range of materials and surface geometries.&nbsp\; We showca
 se two application examples based on real materials where elastic anisotro
 py of the particles induces noticeable effects on macroscopic behavior. Fo
 r example\, we demonstrate the ability to engineer tunable vibrational ban
 d gaps in a stack of grains by merely rotating the constituent spherical p
 articles.
LOCATION:External
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