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Gradient theory for plasticity via homogenization of discrete dislocations

Adriana Garroni, Giovanni Leoni, Marcello Ponsiglione (2010)

Journal of the European Mathematical Society

We deduce a macroscopic strain gradient theory for plasticity from a model of discrete dislocations. We restrict our analysis to the case of a cylindrical symmetry for the crystal under study, so that the mathematical formulation will involve a two-dimensional variational problem. The dislocations are introduced as point topological defects of the strain fields, for which we compute the elastic energy stored outside the so-called core region. We show that the Γ -limit of this energy (suitably rescaled),...

Ground states in complex bodies

Paolo Maria Mariano, Giuseppe Modica (2009)

ESAIM: Control, Optimisation and Calculus of Variations

A unified framework for analyzing the existence of ground states in wide classes of elastic complex bodies is presented here. The approach makes use of classical semicontinuity results, Sobolev mappings and cartesian currents. Weak diffeomorphisms are used to represent macroscopic deformations. Sobolev maps and cartesian currents describe the inner substructure of the material elements. Balance equations for irregular minimizers are derived. A contribution to the debate about the role of the balance...

Ground states in complex bodies

Paolo Maria Mariano, Giuseppe Modica (2008)

ESAIM: Control, Optimisation and Calculus of Variations

A unified framework for analyzing the existence of ground states in wide classes of elastic complex bodies is presented here. The approach makes use of classical semicontinuity results, Sobolev mappings and Cartesian currents. Weak diffeomorphisms are used to represent macroscopic deformations. Sobolev maps and Cartesian currents describe the inner substructure of the material elements. Balance equations for irregular minimizers are derived. A contribution to the debate about the role of the balance...

Homogenization of linear elasticity equations

Jan Franců (1982)

Aplikace matematiky

The homogenization problem (i.e. the approximation of the material with periodic structure by a homogeneous one) for linear elasticity equation is studied. Both formulations in terms of displacements and in terms of stresses are considered and the results compared. The homogenized equations are derived by the multiple-scale method. Various formulae, properties of the homogenized coefficients and correctors are introduced. The convergence of displacment vector, stress tensor and local energy is proved...

Homogenization of many-body structures subject to large deformations

Philipp Emanuel Stelzig (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We give a first contribution to the homogenization of many-body structures that are exposed to large deformations and obey the noninterpenetration constraint. The many-body structures considered here resemble cord-belts like they are used to reinforce pneumatic tires. We establish and analyze an idealized model for such many-body structures in which the subbodies are assumed to be hyperelastic with a polyconvex energy density and shall exhibit an initial brittle bond with their neighbors. Noninterpenetration...

Homogenization of many-body structures subject to large deformations

Philipp Emanuel Stelzig (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We give a first contribution to the homogenization of many-body structures that are exposed to large deformations and obey the noninterpenetration constraint. The many-body structures considered here resemble cord-belts like they are used to reinforce pneumatic tires. We establish and analyze an idealized model for such many-body structures in which the subbodies are assumed to be hyperelastic with a polyconvex energy density and shall exhibit an...

Il criterio dell'energia e l'equazione di Maxwell-Cattaneo nella termoelasticità non lineare

Ettore Laserra, Giovanni Matarazzo (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

By means of the energy method we determine the behaviour of the canonical free energy of an elastic body, immersed in an environment that is thermally and mechanically passive; we use as constitutive equation for the heat flux a Maxwell-Cattaneo like equation.

Incompressibility in Rod and Shell Theories

Stuart S. Antman, Friedemann Schuricht (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

We treat the problem of constructing exact theories of rods and shells for thin incompressible bodies. We employ a systematic method that consists in imposing constraints to reduce the number of degrees of freedom of each cross section to a finite number. We show that it is very difficult to produce theories that exactly preserve the incompressibility and we show that it is impossible to do so for naive theories. In particular, many exact theories have nonlocal effects.

Inequalities of Korn's type, uniform with respect to a class of domains

Ivan Hlaváček (1989)

Aplikace matematiky

Inequalities of Korn's type involve a positive constant, which depends on the domain, in general. A question arises, whether the constants possess a positive infimum, if a class of bounded two-dimensional domains with Lipschitz boundary is considered. The proof of a positive answer to this question is shown for several types of boundary conditions and for two classes of domains.

Injective weak solutions in second-gradient nonlinear elasticity

Timothy J. Healey, Stefan Krömer (2009)

ESAIM: Control, Optimisation and Calculus of Variations

We consider a class of second-gradient elasticity models for which the internal potential energy is taken as the sum of a convex function of the second gradient of the deformation and a general function of the gradient. However, in consonance with classical nonlinear elasticity, the latter is assumed to grow unboundedly as the determinant of the gradient approaches zero. While the existence of a minimizer is routine, the existence of weak solutions is not, and we focus our efforts on that question...

Currently displaying 201 – 220 of 519