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SUMMARY:MechE Colloquium: Zero Stiffness Structures
DTSTART:20250916T120000
DTEND:20250916T130000
DTSTAMP:20260521T033857Z
UID:401ee61ead036dc5621907a005de84e1d94b8d711afd25c965af2bfc
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Simon Guest\, Department of Engineering\, University of 
 Cambridge\nAbstract: The talk will provide a compendium of ’zero-stiffn
 ess’ structures\, describing three classes of structures that remain in 
 a neutral state of equilibrium\, even while they undergo large (and clearl
 y geometrically nonlinear) displacements\, with part or all of each struct
 ure undergoing large (but elastic) deformations. The structures will not b
 e abstract theoretical constructions\, but real structures modelled using 
 reasonable assumptions\, and physical examples will be demonstrated. The t
 hree structures described are at first sight very different: \n\n(1) The 
 first class of structures are simply beam structures with an axisymmetric 
 cross-section\, stress-free when straight\, bent into a torus: they then h
 ave no torsional stiffness. This lack of stiffness is not a new discovery:
  it was described in Thompson & Tait’s 1883 ‘Treatise on Natural Philo
 sophy’.\n\n(2) The second class of structures\, by contrast\, was discov
 ered in our lab fairly recently: during work on prestressed bistable shell
  structures\, we discovered that certain combinations of geometry and pres
 tress could give a structure with no stiffness in a particular bending mod
 e\, even for large deformations.\n\n(3) The third class of structures are 
 sometimes called ’statically-balanced’ structures\, and include\, as a
 n example\, a properly constructed ’Anglepoise’\, or ’Luxo’ lamp. 
 The key to these structures is the use of springs that appear to have a ze
 ro rest-length. We have recently extended the range of possible structures
  of this type to include zero stiffness ’tensegrity’ structures.\n\nTh
 e talk will describe each class of structures\, and provide a straightforw
 ard theory describing how each of the structures works. Although the struc
 tures described are indeed very different\, there are certain aspects that
  are common to them all. The talk will try to tease out a common symmetry 
 theme.\n\n\nBiography: Simon Guest is Professor of Structural Mechanics a
 t the University of Cambridge\, where he is recently stepped down as Head 
 of the Civil Engineering Division.  His research straddles the border bet
 ween traditional structural mechanics and the study of mechanisms.  He ha
 s worked on novel deployable structures and the mechanics and geometry of 
 origami. A recurring theme of his work has been the influence of prestress
  on structural response\, which has led to work on zero-stiffness structur
 es\, bistable structures\, and tensegrity.  His book with Bob Connelly on
  rigidity theory\, “Frameworks\, Tensegrities\, and Symmetry” was rece
 ntly published by Cambridge University Press.
LOCATION:CM 1 4 https://plan.epfl.ch/?room==CM%201%204 https://epfl.zoom.u
 s/j/61360740951
STATUS:CONFIRMED
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