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Sulla nozione di stato per materiali viscoelastici di tipo «rate»

Dario Graffi, Mauro Fabrizio (1989)

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

Si considera un materiale viscoelastico lineare in cui la funzione di rilassamento è la somma di n esponenziali. Lo stato σ di questi sistemi non è necessariamente assegnato dalla storia passata di E , ma è sufficiente fornire il valore iniziale del tensore di deformazione E , del tensore degli sforzi T e delle ( n ⁢ — ⁢ 1 ) sue derivate. Infine per questi materiali abbiamo ottenuto una espressione dell'energia libera come una funzione dello stato di dimensione finita σ .

Sull’estensione di un teorema di Menabrea al caso di una microstruttura a deformazioni finite

Antonio Claudio Grioli (1983)

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

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.

The assessment of the residual post-transient stresses in elastic-perfectly plastic solids subjected to cyclic loads

Castrenze Polizzotto (1993)

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

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 CUDA implementation of the method of lines for the curvature dependent flows

Tomáš Oberhuber, Atsushi Suzuki, Vítězslav Žabka (2011)

Kybernetika

We study the use of a GPU for the numerical approximation of the curvature dependent flows of graphs - the mean-curvature flow and the Willmore flow. Both problems are often applied in image processing where fast solvers are required. We approximate these problems using the complementary finite volume method combined with the method of lines. We obtain a system of ordinary differential equations which we solve by the Runge-Kutta-Merson solver. It is a robust solver with an automatic choice of the...

The regularisation of the N -well problem by finite elements and by singular perturbation are scaling equivalent in two dimensions

Andrew Lorent (2009)

ESAIM: Control, Optimisation and Calculus of Variations

Let K : = S O 2 A 1 ∪ S O 2 A 2 ⋯ S O 2 A N where A 1 , A 2 , ⋯ , A N are matrices of non-zero determinant. We establish a sharp relation between the following two minimisation problems in two dimensions. Firstly the N -well problem with surface energy. Let p ∈ 1 , 2 , Ω ⊂ ℝ 2 be a convex polytopal region. Define I ϵ p u = ∫ Ω d p D u z , K + ϵ D 2 u z 2 d L 2 z and let A F denote the subspace of functions in W 2 , 2 Ω that satisfy the affine boundary condition D u = F on ∂ Ω (in the sense of trace), where F ∉ K . We consider the scaling (with respect to ϵ ) of m ϵ p : = inf u ∈ A F I ϵ p u . Secondly the finite element approximation to the N -well problem without surface...

Currently displaying 461 – 480 of 585