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SUMMARY:Nonsmooth dynamics of extrinsic cohesive models for fracture
DTSTART:20250321T121500
DTEND:20250321T131500
DTSTAMP:20260528T053930Z
UID:b1191c45925cd1ca75a6bfce013f7f2c0b69d5752fa8c45fb7703d20
CATEGORIES:Conferences - Seminars
DESCRIPTION:Vincent Acary\nAbstract\nCohesive zone models are an effective
  tool for simulating fracture in solids. They are generally differentiated
  between intrinsic models\, which have an elasticity of their own at the i
 nterface\, and extrinsic models\, which behave as rigid interfaces prior t
 o the initiation of fracture. The main problems with intrinsic models are 
 as follows: they substantially modify the global elasticity of the materia
 ls\, the interface elasticity is difficult to measure experimentally and t
 hey lead to stiff numerical systems involving strong constraints on the ch
 oice of time–integration schemes and the size of time steps.\n\nIn this 
 work [1\,2]\, we propose an extrinsic cohesive zone model that contains on
 e-sided contact and Coulomb dry friction as residual behaviour at fracture
 . In order to model an extrinsic model\, it is necessary to be able to wri
 te set-valued non-smooth models\, i.e. models that take a set of possible 
 values for a given displacement of the interface. What is fairly standard 
 for unilateral contact and friction is therefore extended to the cohesive 
 part with damage using the tools of convex and variational analysis.\n\nIn
  the spirit of M. Frémond’s work\, the model is written from thermodyna
 mic principles in order to guarantee energy consistency. A time integratio
 n scheme for the dynamics preserves its properties in discrete time. The d
 iscrete system solved at each time step is a well-posed linear complementa
 rity problem\, guaranteeing the existence of solutions and uniqueness in t
 he frictionless case where it is just a convex quadratic program.\n\nWe wi
 ll end this presentation by emphasising the fact that this framework\, whi
 ch makes it possible to model softening behaviour using non-convex interfa
 ce energies\, leads to well-posed convex or co-positive models. This is ma
 inly due to the presence of inertia\, which enables the problem to be well
  defined and solved efficiently.\n\n[1] Nicholas Anton Collins-Craft\, Fra
 nck Bourrier\, Vincent Acary. On the formulation and implementation of ext
 rinsic cohesive zone models with contact. Computer Methods in Applied Mech
 anics and Engineering\, 2022\, 400\, pp.115545. 〈10.1016/j.cma.2022.1155
 45〉. 〈hal-03371667v5〉\n[2] Nicholas Anton Collins-Craft\, Franck Bou
 rrier\, Vincent Acary. On the formulation and implementation of mixed mode
  I and mode II extrinsic cohesive zone models with contact and friction. 2
 024. 〈hal-04447397〉\n\n\nShort bio\nVincent Acary is a research direct
 or at INRIA\, Grenoble-Alpes University Centre. He is head of the TRIPOP t
 eam\, which specialises in the modelling\, analysis\, simulation and contr
 ol of non-smooth dynamical systems. He is particularly interested in the d
 evelopment of numerical methods and simulation codes\, in particular for u
 nilateral contact with friction\, plasticity\, impacts and fracture mechan
 ics. The most important application of this work in recent years has been 
 in the field of natural gravity hazards in mountainous areas. More details
  at https://tripop.inrialpes.fr/people/acary/\n\nSandwiches are offered a
 t the end of the seminar.
LOCATION:GC B1 10 https://plan.epfl.ch/?room==GC%20B1%2010 https://epfl.zo
 om.us/j/69895263418
STATUS:CONFIRMED
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