Il problema dinamico della viscoelasticità lineare : unicità per le soluzioni illimitate nel remoto passato
Initial boundary value problem for a system in elastodynamics with viscosity.
Inverse problems for memory kernels by Laplace transform methods.
Long time behaviour of a Cahn-Hilliard system coupled with viscoelasticity
The long-time behaviour of a unique regular solution to the Cahn-Hilliard system coupled with viscoelasticity is studied. The system arises as a model of the phase separation process in a binary deformable alloy. It is proved that for a sufficiently regular initial data the trajectory of the solution converges to the ω-limit set of these data. Moreover, it is shown that every element of the ω-limit set is a solution of the corresponding stationary problem.
Multiscale modelling of sound propagation through the lung parenchyma
In this paper we develop and study numerically a model to describe some aspects of sound propagation in the human lung, considered as a deformable and viscoelastic porous medium (the parenchyma) with millions of alveoli filled with air. Transmission of sound through the lung above 1 kHz is known to be highly frequency-dependent. We pursue the key idea that the viscoelastic parenchyma structure is highly heterogeneous on the small scale ε and use two-scale homogenization techniques to derive effective...
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.
Numerical analysis of a frictionless viscoelastic piezoelectric contact problem
In this work, we consider the quasistatic frictionless contact problem between a viscoelastic piezoelectric body and a deformable obstacle. The linear electro-viscoelastic constitutive law is employed to model the piezoelectric material and the normal compliance condition is used to model the contact. The variational formulation is derived in a form of a coupled system for the displacement and electric potential fields. An existence and uniqueness result is recalled. Then, a fully discrete scheme...
Numerical Analysis of Evolution Problems in Nonlinear Small Strains Elastoviscoplasticity.
Numerical Treatment of Integro-Differential Equations with a Certain Maximum Propert.
On a 1-D model of stress relaxation in an annealed glass
A 1-D model of a slab of glass of a small thickness is considered. The governing equations are those of the classical 1-D linear viscoelasticity. A load due to the temperature gradients is assumed. The aim is to model the process called annealing. It is shown that an additional load due to structural strain is crucial for the success of the model. Algorithms of a numerical solution of the governing equations are proposed. Numerical results are presented and commented.
On a reliable solution of a Volterra integral equation in a Hilbert space
We consider a class of Volterra-type integral equations in a Hilbert space. The operators of the equation considered appear as time-dependent functions with values in the space of linear continuous operators mapping the Hilbert space into its dual. We are looking for maximal values of cost functionals with respect to the admissible set of operators. The existence of a solution in the continuous and the discretized form is verified. The convergence analysis is performed. The results are applied to...
On one mathematical model of creep in superalloys
In a new micromechanical approach to the prediction of creep flow in composites with perfect matrix/particle interfaces, based on the nonlinear Maxwell viscoelastic model, taking into account a finite number of discrete slip systems in the matrix, has been suggested; high-temperature creep in such composites is conditioned by the dynamic recovery of the dislocation structure due to slip/climb motion of dislocations along the matrix/particle interfaces. In this article the proper formulation of the...
On some viscoelastic models
Sia un sistema linearmente viscoelastico, omogeneo ed isotropo, caratterizzato dalla funzione di memoria , tipica di numerosi polimeri solidi. Si dimostra che la soluzione fondamentale dell’operatore integrodifferenziale che descrive i moti di è, in ogni punto del suo supporto, maggiorata da quella relativa ad un opportuno solido standard Di conseguenza, è possibile applicare all’analisi qualitativa dei moti di alcuni risultati stabiliti in [10], quali proprietà asintotiche, principi...
On the buckling of a viscoelastic rod
On the Cauchy problem in linear viscoelasticity
Con riferimento all’operatore integrodifferenziale della viscoelasticità lineare nella formulazione creep, si determina la soluzione fondamentale in corrispondenza di un’arbitraria funzione di memoria. Di conseguenza viene risolto esplicitamente il problema di Cauchy relativo al moto unidimensionale di un sistema viscoelastico , omogeneo ed isotropo, determinato da dati iniziali e storia di stress comunque prefissati. Successivamente, nell’ambito di opportune ipotesi di memoria labile, si dimostrano...
On the compressed elastic rod with rotary inertia on a viscoelastic
On the Equivalence of the Riemann-Liouville and the Caputo Fractional Order Derivatives in Modeling of Linear Viscoelastic Materials
Mathematics Subject Classification: 26A33In the process of constructing empirical mathematical models of physical phenomena using the fractional calculus, investigators are usually faced with the choice of which definition of the fractional derivative to use, the Riemann-Liouville definition or the Caputo definition. This investigation presents the case that, with some minimal restrictions, the two definitions produce completely equivalent mathematical models of the linear viscoelastic phenomenon....
On the thermal aspect of dynamic contact problems
A short survey of available existence results for dynamic contact problems including heat generation and heat transfer is presented.
On weak solutions to a viscoelasticity model
Optimal Poiseuille flow in a finite elastic dyadic tree
In this paper we construct a model to describe some aspects of the deformation of the central region of the human lung considered as a continuous elastically deformable medium. To achieve this purpose, we study the interaction between the pipes composing the tree and the fluid that goes through it. We use a stationary model to determine the deformed radius of each branch. Then, we solve a constrained minimization problem, so as to minimize the viscous (dissipated) energy in the tree. The key...