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SUMMARY:MEchanics GAthering -MEGA- Seminar: Untangling the mechanics of el
 astic knots and not-knots
DTSTART:20181220T161500
DTEND:20181220T173000
DTSTAMP:20261002T001152Z
UID:9dc536f379eac5f506c0f24554ee6000911c338426e1873df6f7a6fb
CATEGORIES:Conferences - Seminars
DESCRIPTION:Paul Johanns & Paul Grandgeorge\, fleXLab\, EPFL\nAbstract\
 nKnots are key for a wide variety of applications such as mooring ships to
  docks\, ensuring the safety of a falling climber or fastening surgical su
 ture threads. Even if knots have been used in hundreds of configurations f
 or millennia\, the understanding of their mechanical behavior remains main
 ly empirical. Knot theory\, a well-established field of mathematics\, ten
 ds to focus on idealized\, non-elastic knots. Moreover\, analytical models
  based on Kirchhoff’s theory for elastic rods are limited to simple knot
 s in loose configurations. Such descriptions are too abstract for practica
 l settings. Realistic physical knots are in general tight\, with no separa
 tion of length scales\; the overall size of the knot\, the diameter of the
  rod\, and its characteristic radii of curvature are all of the same order
  of magnitude. In addition\, functioning knots involve elastic deformation
  of the thread\, self-contact\, and nontrivial frictional interactions.\nW
 e tackle this problem by performing high-precision experiments to acquire 
 unprecedented experimental data on the geometry and deformation of simple 
 open-knots\, focusing specifically on the overhand and the figure-of-eight
  knots.Furthermore\, in order to gain better insight into this complex cla
 ss of problems\, we also study the ‘not-knot’\; a simpler model system
  that comprises the clasp of two bent elastic rods brought together into m
 echanical contact. We believe that considering complex tight knots as asse
 mblies of simple not-knots will provide a solid foundation to develop much
  needed predictive models for knotted structures. We make use of X-ray mic
 ro computed tomography (micro-CT) to acquire volumetric information of kno
 tted configurations on homogeneous elastomeric rods. More specifically\, w
 e focus on the centerline geometry and the regions of self-contact. System
 atic exploration of parameter space enables us to construct a family of so
 lutions of not-knot configurations. We envision that the physical insight 
 gained from this experimental characterization will form the basis for fut
 ure predictive models for physical knots.
LOCATION:MED 2 2423 https://plan.epfl.ch/?room=MED22423
STATUS:CONFIRMED
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