Existence of regular solutions for a one-dimensional simplified perfect-plastic problem with a unilateral gradient constraint.
Existence of regular solutions for a one-dimensional simplified perfect-plastic problem
Existence Result for the Displacement Field of Elastic Body
Extremum theorem and convergence criterion for an iterative solution to the finite-step problem in elastoplasticity with mixed nonlinear hardening
For a class of elastic-plastic constitutive laws with nonlinear kinematic and isotropic hardening, the problem of determining the response to a finite load step is formulated according to an implicit backward difference scheme (stepwise holonomic formulation), with reference to discrete structural models. This problem is shown to be amenable to a nonlinear mathematical programming problem and a criterion is derived which guarantees monotonie convergence of an iterative algorithm for the solution...
Folded shells : a variational approach
Free energy and internal variables in linear viscoelasticity
In connection with the determination of the free energy functional for the viscoelastic stress tensor, a viscoelastic material is considered as described by a material with internal variables. In this framework the free energy is uniquely determined. It proves to be the minimal one in the class of thermodynamically admissible free energies.
Fully explicit quasiconvexification of the mean-square deviation of the gradient of the state in optimal design.
Homogenization and effective properties of plates weakened by partially penetrating fissures : convergence and duality
Hybrid level set phase field method for topology optimization of contact problems
The paper deals with the analysis and the numerical solution of the topology optimization of system governed by variational inequalities using the combined level set and phase field rather than the standard level set approach. The standard level set method allows to evolve a given sharp interface but is not able to generate holes unless the topological derivative is used. The phase field method indicates the position of the interface in a blurry way but is flexible in the holes generation. In the...
Mathematical study of an evolution problem describing the thermomechanical process in shape memory alloys
In this paper we prove existence, uniqueness, and continuous dependence for a one-dimensional time-dependent problem related to a thermo-mechanical model of structural phase transitions in solids. This model assumes the free energy depending on temperature, macroscopic deformation and also on the proportions of the phases. Here we neglect regularizing terms in the momentum balance equation and in the constitutive laws for the phase proportions.
Modellazione e calcolo di strutture in materiale non resistente a trazione
Si affronta il problema del calcolo dello stato tensionale in strutture costituite da materiale non resistente a trazione ed elastico lineare a compressione. Si formula la legge costitutiva e se ne fornisce l'espressione esplicita nel caso di stati tensionali monoassiali, biassiali e triassiali. Si imposta quindi il problema dell'equilibrio elastico e si discute sulla condizione da imporre ai carichi affinché venga assicurata l'esistenza della soluzione. Si sviluppa la formulazione agli elementi...
Non unicità dell'energia libera per materiali viscoelastici
La non unicità dell'energia libera per un materiale viscoelastico di tipo «rate» viene provata mediante la determinazione di un controesempio.
Note critiche sui carichi di collasso dei continui bidimensionali isotropi
Nei continui bidimensionali isotropi in fase fessurata si dimostra, nella sola ipotesi che le linee di rottura rappresentino univocamente il meccanismo di collasso, la impossibilità di ottenere un moltiplicatore ottimale del carico. La configurazione reale può essere definita considerando anche la capacità deformativa del continuo in esame.
Note on a mixed variational principle in finite elasticity
In the present context the variation is performed keeping the deformed configuration fixed while a suitable material stress tensor and the material coordinates are required to vary independently. The variational principle turns out to be equivalent to an equilibrium problem of placements and tractions prescribed at the boundary of a body of finite extent.
Numerical minimization of eigenmodes of a membrane with respect to the domain
In this paper we introduce a numerical approach adapted to the minimization of the eigenmodes of a membrane with respect to the domain. This method is based on the combination of the Level Set method of S. Osher and J.A. Sethian with the relaxed approach. This algorithm enables both changing the topology and working on a fixed regular grid.
Numerical minimization of eigenmodes of a membrane with respect to the domain
In this paper we introduce a numerical approach adapted to the minimization of the eigenmodes of a membrane with respect to the domain. This method is based on the combination of the Level Set method of S. Osher and J.A. Sethian with the relaxed approach. This algorithm enables both changing the topology and working on a fixed regular grid.
On a problem of potential wells.
On an unconventional variational method for solving the problem of linear elasticity with Neumann or periodic boundary conditions
A new variational formulation of the linear elasticity problem with Neumann or periodic boundary conditions is presented. This formulation does not require any quotient spaces and is advisable for finite element approximations.
On Reissner's variational theorem for boundary values in linear elasticity
On the mechanical behaviour of laminated curved beams: a simple model which takes into account the warping effects
A mechanical one-dimensional model which describes the dynamical behaviour of laminated curved beams is formulated. It is assumed that each lamina can be regarded as a Timoshenko's beam and that the rotations of the cross sections can differ from one lamina to another. The relative displacements at the interfaces of adjacent laminae are assumed to be zero. Consequently the model includes a shear deformability, due to the warping of the cross beam section consequent to the variability of the laminae...