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VERSION:2.0
PRODID:-//Memento EPFL//
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SUMMARY:CECAM Workshop: "3D cracks and crack stability"
DTSTART:20230614T080000
DTEND:20230616T180000
DTSTAMP:20260407T111501Z
UID:341e7eedf793bc723f9a3801192915e813707a6bbf4dbdf13fa495c0
CATEGORIES:Conferences - Seminars
DESCRIPTION:You can apply to participate and find all the relevant informa
 tion (speakers\, abstracts\, program\,...) on the event website: https://
 www.cecam.org/workshop-details/1196\n\nDescription\nThe fracture of solids
  has formed the cornerstone of engineering science since Galileo first pos
 ed the question of the maximum load before rupture of a beam subjected to 
 tension. Our current understanding of the mechanics of fracture is formula
 ted in the theory of linear elastic fracture mechanics\, which predicts a 
 singular stress at the crack tip\, making the problem challenging on all l
 evels. Experiments show that the mechanics and physics of brittle fracture
  are typically irregular\, with the emergence of surface features and text
 ure that are non-smooth. Even when a crack abides the over-all symmetry of
  planar loading conditions\, characteristic fracture surface structures em
 erge with a strong velocity dependence\, and can even persist at extremely
  low velocities. The emergent structures are indicative of non-linearities
  in the dynamics of a crack\, and are the hallmarks of crack instability.
  \nThe long-standing paradigm in fracture mechanics\, established from li
 near perturbation theory\, is that any initial disturbance should decay or
  disperse\, independent of its amplitude. Recent calculations challenge th
 is paradigm [1-3]\, and instead suggest that due to non-linearities in the
  dynamics\, the crack surface is susceptable to breaking planar symmetry f
 or sufficiently large disturbances. Experiments support these calculations
 \, as even quasi-static cracks exhibit structure and surface features that
  do not decay as the crack progresses [4]. Indeed\, such disturbances can 
 have global consequences\, as a rigid inclusion can completely arrest a pr
 opagating crack [5]. \nRecent numerical calculations using the phase-fiel
 d method are capable of reproducing the texture and features of these dyna
 mics\, if at an altered threshold velocity for the onset of instability [6
 ]. A similar numerical method shows that a quasi-static crack subjected to
  mixed mode-I / mode-III loading will readily develop lances and a corruga
 ted pattern [7]. In both cases\, the overall planar symmetry of the crack 
 is broken\, and a fully-3D stress state develops at the crack tip. This is
  significant\, because such a stress state is extremely challenging to add
 ress analytically\, and nearly impossible to characterize using existing e
 xperimental methods. While these numerical calculations led to advances in
  the methods available to the numericist to calculate the mechanics of mor
 e complex crack tip loading conditions\, fundamental questions about the p
 recise value of the threshold for the development of e.g. lances\, or micr
 obranches in the dynamic case\, remain unanswered. \nExperimental develop
 ments using a variety of materials are now positioned to inform numerical 
 calculation on the most general loading cases\, including fully 3D loading
  conditions\, and mixed planar/ non-planar loading. Indeed\, direct observ
 ations of crack tips in brittle hydrogels emphsize the sensitivity of a cr
 ack to mixed-mode loading conditions [8]\, and even the emergence of plana
 r symmetry breaking [9]. Method development\, including direct microscopic
  measurement of crack tip opening displacement and deformation [10]\, or m
 ore sophisticated speckle-holography methods [11]\, stand to facilitate di
 rect measurement of 3D deformation field\, specifically for materials unde
 r high-strain near sharp geometries such as a crack tip.\nTaken together\,
  these advances suggest that the field will benefit from an opportunity to
  identify key outstanding questions\, and discuss the best approaches to i
 mprove predictability of material failure in the most general 3D case.\n\n
 Reference\n[1] I. Kolvin\, J. Fineberg\, M. Adda-Bedia\, Phys. Rev. Lett.\
 , 119\, 215505 (2017)\n[2] M. Lebihain\, J. Leblond\, L. Ponson\, Europea
 n Journal of Mechanics - A/Solids\, 104602 (2022)\n[3] A. Vasudevan\, L. P
 onson\, A. Karma\, J. Leblond\, Journal of the Mechanics and Physics of So
 lids\, 137\, 103894 (2020)\n[4] M. Wang\, M. Adda-Bedia\, J. Kolinski\, J
 . Fineberg\, Journal of the Mechanics and Physics of Solids\, 161\, 10479
 5 (2022)\n[5] L. Rozen-Levy\, J. Kolinski\, G. Cohen\, J. Fineberg\, Phys.
  Rev. Lett.\, 125\, 175501 (2020)\n[6] J. Bleyer\, C. Roux-Langlois\, J. 
 Molinari\, Int. J. Fract.\, 204\, 79-100 (2016)\n[7] A. Pons\, A. Karma\,
  Nature\, 464\, 85-89 (2010)\n[8] K. Pham\, K. Ravi-Chandar\, Int. J. Fra
 ct.\, 206\, 229-244 (2017)\n[9] T. Baumberger\, C. Caroli\, D. Martina\, 
 O. Ronsin\, Phys. Rev. Lett.\, 100\, 178303 (2008)\n[10] Taureg\, Albert\
 , and John M. Kolinski. "Dilute concentrations of submicron particles do n
 ot alter the brittle fracture of polyacrylamide hydrogels." arXiv preprint
  arXiv:2004.04137 (2020).\n[11] S. Aime\, M. Sabato\, L. Xiao\, D. Weitz\,
  Phys. Rev. Lett.\, 127\, 088003 (2021)
LOCATION:BCH 2103 https://plan.epfl.ch/?room==BCH%202103
STATUS:CONFIRMED
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