Shape optimization in two-dimensional elasticity by the dual finite element method
Shape optimization of an elasto-perfectly plastic body
Within the range of Prandtl-Reuss model of elasto-plasticity the following optimal design problem is solved. Given body forces and surface tractions, a part of the boundary, where the (two-dimensional) body is fixed, is to be found, so as to minimize an integral of the squared yield function. The state problem is formulated in terms of stresses by means of a time-dependent variational inequality. For approximate solutions piecewise linear approximations of the unknown boundary, piecewise constant...
Shape optimization of an elasto-plastic body for the model with strain- hardening
The state problem of elasto-plasticity (for the model with strain-hardening) is formulated in terms of stresses and hardening parameters by means of a time-dependent variational inequality. The optimal design problem is to find the shape of a part of the boundary such that a given cost functional is minimized. For the approximate solutions piecewise linear approximations of the unknown boundary, piecewise constant triangular elements for the stress and the hardening parameter, and backward differences...
Shape optimization of elastic axisymmetric bodies
The shape of the meridian curve of an elastic body is optimized within a class of Lipschitz functions. Only axisymmetric mixed boundary value problems are considered. Four different cost functionals are used and approximate piecewise linear solutions defined on the basis of a finite element technique. Some convergence and existence results are derived by means of the theory of the appropriate weighted Sobolev spaces.
Shape optimization of elasto-plastic axisymmetric bodies
A minimization of a cost functional with respect to a part of a boundary is considered for an elasto-plastic axisymmetric body obeying Hencky's law. The principle of Haar-Kármán and piecewise linear stress approximations are used to solve the state problem. A convergence result and the existence of an optimal boundary is proved.
Shape optimization of elastoplastic bodies obeying Hencky's law
A minimization of a cost functional with respect to a part of the boundary, where the body is fixed, is considered. The criterion is defined by an integral of a yield function. The principle of Haar-Kármán and piecewise constant stress approximations are used to solve the state problem. A convergence result and the existence of an optimal boundary is proved.
Simulation and design of extraction and separation fluidic devices
We present the combination of a state control and shape design approaches for the optimization of micro-fluidic channels used for sample extraction and separation of chemical species existing in a buffer solution. The aim is to improve the extraction and identification capacities of electroosmotic micro-fluidic devices by avoiding dispersion of the extracted advected band.
Simulation and design of extraction and separation fluidic devices
We present the combination of a state control and shape design approaches for the optimization of micro-fluidic channels used for sample extraction and separation of chemical species existing in a buffer solution. The aim is to improve the extraction and identification capacities of electroosmotic micro-fluidic devices by avoiding dispersion of the extracted advected band.
Simulation of anisotropic motion by mean curvature -- comparison of phase field and sharp interface approaches.
Singular solutions of a transmission problem in plane linear elasticity for wedge-shaped regions.
Singularity problems in linear elastodynamics
Slab analogy in theory and practice of conforming equilibrium stress models for finite element analysis of plane elastostatics
The fundamental problem in the application of the principle of complementary energy is the construction of suitable subsets that approximate the set of all statically admissible fields satisfying both the conditions of equilibrium inside the body and the static boundary conditions. The notion “slab analogy” is motivated and the interface conditions for the Airy stress function are established at the contact of two domains. Some spaces of types of conforming equilibrium stress elements, which can...
Some methods for calculating stiffness properties of periodic structures
We present a general numerical method for calculating effective elastic properties of periodic structures based on the homogenization method. Some concrete numerical examples are presented.
Sulla nozione di stato per materiali viscoelastici di tipo «rate»
Si considera un materiale viscoelastico lineare in cui la funzione di rilassamento è la somma di esponenziali. Lo stato di questi sistemi non è necessariamente assegnato dalla storia passata di , ma è sufficiente fornire il valore iniziale del tensore di deformazione , del tensore degli sforzi e delle sue derivate. Infine per questi materiali abbiamo ottenuto una espressione dell'energia libera come una funzione dello stato di dimensione finita .
Sull’estensione di un teorema di Menabrea al caso di una microstruttura a deformazioni finite
In the present work an extension of a classical Menabrea’s theorem on a variational principle of the second potential energy is considered. Such extension deals with hyperelastic micropolar media without constraints.
Sur une méthode de calcul de structures soumises à des chargements cycliques : l'homogénéisation en temps
The assessment of the residual post-transient stresses in elastic-perfectly plastic solids subjected to cyclic loads
For elastic-perfectly plastic solids (or structures) subjected to quasi-static cyclic loads, variational methods are presented for the direct eyâluation of the post-transient residual stresses, that is, the residual stresses in the structure at the end of the transient response phase, consequence of the plastic strains therein produced and crucial to predict the subsequent steady structural behaviour. The problem of the evaluation of the number of cycles spanned by the transient response is also...
The contact problem for an elastic orthotropic plate supported by periodically located bars of equal resistance.
The convergence of a Galerkin approximation scheme for an extensible beam
The dynamics of a tied body against an obstacle