A Galerkin spectral approximation in linearized beam theory
A maximum reduced dissipation principle for nonassociative plasticity
The concept of reduced plastic dissipation is introduced for a perfectly plastic rate-independent material not obeyng the associated normality rule and characterized by a strictly convex plastic potential function. A maximum principle is provided and shown to play the role of variational statement for the nonassociative constitutive equations. The Kuhn-Tucker conditions of this principle describe the actual material behaviour as that of a (fictitious) composite material with two plastic constituents,...
A minimum principle in the dynamics of elastic materials with voids
In the context of the linear, dynamic problem for elastic bodies with voids, a minimum principle in terms of mechanical energy is stated. Involving a suitable (Reiss type) function in the minimizing functional, the minimum character achieved in the Laplace-transform domain is preserved when going back to the original time domain. Initial-boundary conditions of quite general type are considered.
A New Class of Variational Problems Arising in the Modeling of Elastic Multi-Structures.
A numerical method for detecting singular minimizers of multidimensional problems in nonlinear elasticity.
A space-time variational formulation for the boundary integral equation in a 2D elastic crack problem
A variational model for nonlinear elastic plates.
A variationally consistent generalized variable formulation of the elastoplastic rate problem
The elastoplastic rate problem is formulated as an unconstrained saddle point problem which, in turn, is obtained by the Lagrange multiplier method from a kinematic minimum principle. The finite element discretization and the enforcement of the min-max conditions for the Lagrangean function lead to a set of algebraic governing relations (equilibrium, compatibility and constitutive law). It is shown how important properties of the continuum problem (like, e.g., symmetry, convexity, normality) carry...
Analyse numérique d'un modèle de coques de Koiter discrétisé en base cartésienne par éléments finis DKT
Approximation of a nonlinear thermoelastic problem with a moving boundary via a fixed-domain method
The thermoelastic stresses created in a solid phase domain in the course of solidification of a molten ingot are investigated. A nonlinear behaviour of the solid phase is admitted, too. This problem, obtained from a real situation by many simplifications, contains a moving boundary between the solid and the liquid phase domains. To make the usage of standard numerical packages possible, we propose here a fixed-domain approximation by means of including the liquid phase domain into the problem (in...