Forthcoming Seminars › Seminar Series

OxMOS Workshop/Meeting/Lecture

Mon, 14/01/2008
15:00 		Professor Qiang Du (Penn State University) OxMOS Workshop/Meeting/Lecture Add to calendar DH 3rd floor SR
Phase field modelling and simulation of some interface problems
Professor Qiang Du will go over some work on modelling interface/microstructures with curvature dependent energies and also the effect of elasticity on critical nuclei morphology.
Mon, 21/01/2008
11:00 		Mariano Vazquez (Barcelona) OxMOS Workshop/Meeting/Lecture Add to calendar DH 3rd floor SR
High Performance Computational Mechanics in Marenostrum supercomputer
Computational Mechanics (CM) has become a scientific discipline in itself, being High Perfomance Computational Mechanics (HPCM) a key sub-discipline. The effort for the most efficient use of distributed memory machines provides a different perspective to CM scientists relative to a wide range of topics, from the very physics of the problem to solve to the numerical method used. Marenostrum supercomputer is the largest facility in Europe and the 5th in the world (top500.org - Spring 2007). This talk describes the research lines in the CASE Dpt. of the BSC applied to Aerospace, Bio-mechanics, Geophysics or Environment, through the development of Alya, the in-house HPCM code for complex coupled problems capable of running efficiently in large distributed memory facilities.
Thu, 24/01/2008
11:00 		Bernhard Langwallner and Konstantinos Koumatos (Oxford) OxMOS Workshop/Meeting/Lecture Add to calendar DH 3rd floor SR
OxMOS Team Meeting
Tue, 19/02/2008
10:00 		Timothy Squires and Pras Pathmanathan (Oxford) OxMOS Workshop/Meeting/Lecture Add to calendar Gibson 1st Floor SR
OxMOS Team Meeting
Thu, 28/02/2008
10:00 		Patrizo Neff (University of Essen & T.U. Darmstadt) OxMOS Workshop/Meeting/Lecture Add to calendar Gibson 1st Floor SR
The $ \Gamma $-limit of a finite-strain Cosserat model for asymptotically thin domains versus a formal dimensional reduction
We are concerned with the derivation of the $ \Gamma $-limit to a three-dimensional geometrically exact Cosserat model as the relative thickness $ h>0 $ of a flat domain tends to zero. The Cosserat bulk model involves already exact rotations as a second independent field and this model is meant to describe defective elastic crystals liable to fracture under shear. It is shown that the $ \Gamma $-limit based on a natural scaling assumption consists of a membrane like energy contribution and a homogenized transverse shear energy both scaling with $ h $, augmented by an additional curvature stiffness due to the underlying Cosserat bulk formulation, also scaling with $ h $. No specific bending term appears in the dimensional homogenization process. The formulation exhibits an internal length scale $ L_c $ which survives the homogenization process. A major technical difficulty, which we encounter in applying the $ \Gamma $-convergence arguments, is to establish equi-coercivity of the sequence of functionals as the relative thickness $ h $ tends to zero. Usually, equi-coercivity follows from a local coerciveness assumption. While the three-dimensional problem is well-posed for the Cosserat couple modulus $ \mu_c\ge 0 $, equi-coercivity forces us to assume a strictly positive Cosserat couple modulus $ \mu_c>0 $. The $ \Gamma $-limit model determines the midsurface deformation $ m\in H^{1,2}(\omega,\R^3) $. For the case of zero Cosserat couple modulus $ \mu_c=0 $ we obtain an estimate of the $ \Gamma-\liminf $ and $ \Gamma-\limsup $, without equi-coercivity which is then strenghtened to a $ \Gamma $-convergence result for zero Cosserat couple modulus. The classical linear Reissner-Mindlin model is "almost" the linearization of the $ \Gamma $-limit for $ \mu_c=0 $ apart from a stabilizing shear energy term.

For any corrections/updates to these listings, please contact seminars [-at-] maths [dot] ox [dot] ac [dot] uk.

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