Forthcoming events in this series


Wed, 27 Apr 2011
14:00
Gibson 1st Floor SR

Isoperimetric inequalities and cavity interactions in nonlinear elasticity

Duvan Henao
(Université Pierre et Marie Curie - Paris VI)
Abstract

We consider the problem of cavitation in nonlinear elasticity, or the formation of macroscopic cavities in elastic materials from microscopic defects, when subjected to large tension at the boundary.

The main goal is to determine the optimal locations where the body prefers the cavities to open, the preferred number of cavities, their optimal sizes, and their optimal shapes. To this aim it is necessary to analyze the elastic energy of an incompressible deformation creating multiple cavities, in a way that accounts for the interaction between the cavitation singularities. Based on the quantitative version of the isoperimetric inequality, as well as on new explicit constructions of incompressible deformations creating cavities of different shapes and sizes, we provide energy estimates showing that, for certain loading conditions, there are only the following possibilities:

  • only one cavity is created, and if the loading is isotropic then it is created at the centre
  • multiple cavities are created, they are spherical, and the singularities are well separated
  • there are multiple cavities, but they act as a single spherical cavity, they are considerably distorted, and the distance between the cavitation singularities must be of the same order as the size of the initial defects contained in the domain.

In the latter case, the formation of thin structures between the cavities is observed, reminiscent of the initiation of ductile fracture by void coalesence.

This is joint work with Sylvia Serfaty (LJLL, Univ. Paris VI).

Wed, 06 Jan 2010 09:00 -
Fri, 08 Jan 2010 13:00
L2

New Developments in Elasticity: the Legacy of Robert Hooke

Speaker names are listed below.
Abstract

Speakers include:

* David Abrahams (Manchester, UK); * Stuart Antman (Maryland, USA); * Martine Ben Amar (Ecole Normale Supérieure, France); * Mary Boyce (MIT, USA); * John Hutchinson (Harvard, USA); * Nadia Lapusta (Caltech, USA); * John Maddocks (Lausanne, Switzerland); * Stefan Mueller (Bonn, Germany); * Christoph Ortner (Oxford, UK); * Ares Rosakis (Caltech, USA); * Hanus Seiner (Academy of Sciences, Czech Republic); * Eran Sharon (Hebrew University, Israel); * Lev Truskinovsky (Lab de Mécanique des Solids, France); * John Willis (Cambridge, UK).

Thu, 10 Dec 2009

12:00 - 13:00
Gibson 1st Floor SR

OxMOS Team Meeting

Christoph Ortner; Cameron Hall
Mon, 07 Dec 2009 09:00 -
Tue, 08 Dec 2009 17:00
L2

Workshop on Atomistic Models of Solids

Speaker names are listed below.
(Oxford)
Abstract

Speakers include:

* Graeme Ackland (School of Physics and Astronomy, Edinburgh) * Andrea Braides (Rome II) * Thierry Bodineau (École Normale Supérieure, Paris) * Matthew Dobson (Minneapolis) * Laurent Dupuy (CEA, Saclay) * Ryan Elliott (Minneapolis) * Roman Kotecky (Warwick) * Carlos Mora-Corral (BCAM, Bilbao) * Stefano Olla (CEREMADE, Paris-Dauphine) * Bernd Schmidt (TU Munich) * Lev Truskinovsky (École Polytechnique, Palaiseau) * Min Zhou (Georgia Tech, Atlanta)

Thu, 12 Nov 2009
11:00
Gibson 1st Floor SR

OxMOS Team Meeting

Richard Norton; Siobhan Burke
Tue, 07 Jul 2009

10:00 - 11:00
Gibson 1st Floor SR

OxMOS Team Meeting

K. Koumatos, T. Squires
(Oxford)
Wed, 03 Jun 2009

09:00 - 18:00
L2

Multiscale Models in Solid Mechanics

M. Ortiz, M. Luskin, F.Legoll, O. Pierre-Louis, A.Raoult
Abstract

Macroscopic properties of solids are inherently connected to their micro- and nano-scale details. For example, the microstructure and defect distribution influence the elastic and plastic properties of a crystal while the details of a defect are determined by its elastic far-field. The goal of multi-scale modelling is to understand such connections between microscopic and macroscopic material behaviour. This workshop brings together researchers working on different aspects of multi-scale modelling of solids: mathematical modelling, analysis, numerical computations, and engineering applications.

Wed, 20 May 2009

15:00 - 16:00
Gibson 1st Floor SR

OxMOS Team Meeting

Y. Sengul, P. Pathmanathan
(Oxford)
Thu, 12 Mar 2009

09:00 - 10:00
Gibson 1st Floor SR

OxMOS Team Meeting

Benson Muite and Yichao Zhu
(Oxford)
Thu, 19 Feb 2009

09:00 - 10:00
Gibson 1st Floor SR

OxMOS Team Meeting

Gareth Jones and Richard Norton
(Oxford)
Thu, 29 Jan 2009

09:00 - 10:00
Gibson 1st Floor SR

OxMOS Team Meeting

Duvan Henao and Christoph Ortner
(Oxford University Mathematical Institute)
Wed, 03 Dec 2008

09:00 - 10:00
DH 3rd floor SR

OxMOS Team Meeting

Bernhard Langwallner and Timothy Squires
Tue, 04 Nov 2008

09:00 - 10:00
DH 3rd floor SR

OxMOS Team Meeting

Pras Pathmanathan and Yasemin Sengul
Fri, 31 Oct 2008

11:45 - 17:00
Gibson 1st Floor SR

Dislocations Worshop

Gabor Csanyi and others
Abstract

11.30 Coffee (1st floor Gibson Common Room).

11.45 Atomistics and Dislocations - Gabor Csanyi (followed by a short time for discussion).

13.00 Sandwich lunch (1st floor Common Room).

13.45 (approx) Persistent Slip Bands (PSB's) - Angus Wilkinson and/or Jon Chapman.

14:30 Discussion.

Fri, 03 Oct 2008

10:00 - 17:00
L2

Elastic Stability Workshop

Becca Thomases, Yury Grabovsky, L Mahadevan, Tim Healey, Heinrich Freistühler and Robin Knops
Abstract

The workshop will address current issues related to the stability of solutions in nonlinear elasticity, including local energy minimizers, the stability of growing bodies, global existence for small data, bifurcation and continuation of solutions, and Saint-Venant’s principle.

Tue, 16 Sep 2008

15:30 - 16:30
Gibson 1st Floor SR

A Posteriori Error Estimates for PDE Constrained Optimization with Pointwise State Constraints

Winnifried Wollner
(Heidelberg)
Abstract
This talk is devoted to adaptivity in optimal control of PDEs with special emphasis on barrier methods for pointwise state constraints. The talk is divided into to major parts, first we will discuss the case of additional pointwise inequality constraints on the state variable, then we will transfer the results to constraints on the gradient of the state. Each part will start with a discussion of necessary optimality conditions and a brief overview about what is known and what is not known concerning a priori analysis. Then a posteriori error estimates for the discretization error as well as for the error from the barrier method will be presented. Finally we show some simple examples to illustrate the behavior of the estimators. 
The talk will be followed by an informal tea in the Gibson Building seminar room giving an opportunity to chat with Winnifried Wollner and Amit Acharya (our other current OxMOS visitor)
Mon, 09 Jun 2008

12:00 - 13:00
Gibson 1st Floor SR

OxMOS Team Meeting

Christoph Ortner and Gareth Jones
(Oxford)
Tue, 27 May 2008

12:00 - 13:00
Gibson 1st Floor SR

OxMOS Team Meeting

Duvan Henao and Xianmin Xu
(Oxford)
Abstract
Duvan will be talking on "Cavitation, invertibility, and the continuity of the determinant in critical cases", and Xianmin willl be talking about his work on numerical simulations of cavitation in nonlinear elasticity
Wed, 21 May 2008

12:00 - 13:00
DH 3rd floor SR

The effective static and dynamic properties of composite media

William Parnell
(Manchester University)
Abstract
The effective properties of composite media are defined by the constituent phase properties (elastic moduli, thermal conductivities,etc), their volume fractions, and their distribution throughout the medium. In the case of constituents distributed periodically, there exist many homogenization theories which can provide exact solutions for the effective properties. However, the case of the effective properties of random media remains largely an open problem.

In this talk we will begin by discussing the notion of homogenization as an extension to the continuum assumption and regimes in which it breaks down. We then discuss various approaches to dealing with randomness whilst determining the effective properties of acoustic, thermal and elastic media.  In particular we show how the effective properties depend on the randomness of the microstructure

Tue, 06 May 2008

15:15 - 16:15
Gibson 1st Floor SR

The effective static and dynamic properties of composite media

Dr Willam Parnell
(University of Manchester)
Abstract
OxMOS visitor Dr William Parnell will be introducing his work. This will be followed by an informal tea for anyone who wants to stay on to talk to Dr Parnell.

Further information available from @email Tel 80609

All welcome!