All a b c d e f g h i j k l m n o p q r s t u v w x y z Other

Page 1

Displaying 1 – 20 of 20

Showing per page

An extension of small-strain models to the large-strain range based on an additive decomposition of a logarithmic strain

Horák, Martin, Jirásek, Milan (2013)

Programs and Algorithms of Numerical Mathematics

This paper describes model combining elasticity and plasticity coupled to isotropic damage. However, the conventional theory fails after the loss of ellipticity of the governing differential equation. From the numerical point of view, loss of ellipticity is manifested by the pathological dependence of the results on the size and orientation of the finite elements. To avoid this undesired behavior, the model is regularized by an implicit gradient formulation. Finally, the constitutive model is extended...

Dynamics of shock waves in elastic-plastic solids

N. Favrie, S. Gavrilyuk (2011)

ESAIM: Proceedings

The Maxwell type elastic-plastic solids are characterized by decaying the absolute values of the principal components of the deviatoric part of the stress tensor during the plastic relaxation step. We propose a mathematical formulation of such a model which is compatible with the von Mises criterion of plasticity. Numerical examples show the ability of the model to deal with complex physical phenomena.

La valutazione teorica di spostamenti e rotazioni in fase anelastica negli elementi monodimensionali in cemento armato

Edoardo Cosenza, Carlo Greco, Gaetano Manfredi (1991)

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

Si presenta una metodologia di calcolo per valutare lo stato deformativo, in termini di curvature, rotazioni e spostamenti, negli elementi monodimensionali in cemento armato soggetti a carichi monotoni in regime anelastico. In particolare si tiene conto dello scorrimento acciaio calcestruzzo, e della collaborazione offerta dal calcestruzzo teso fra due successive lesioni. Si presenta il sistema di equazioni non-lineari che regge il problema, con le relative condizioni al contorno, e si discute in...

Linearized plastic plate models as Γ-limits of 3D finite elastoplasticity

Elisa Davoli (2014)

ESAIM: Control, Optimisation and Calculus of Variations

The subject of this paper is the rigorous derivation of reduced models for a thin plate by means of Γ-convergence, in the framework of finite plasticity. Denoting by ε the thickness of the plate, we analyse the case where the scaling factor of the elasto-plastic energy per unit volume is of order ε2α−2, with α ≥ 3. According to the value of α, partially or fully linearized models are deduced, which correspond, in the absence of plastic deformation, to the Von Kármán plate theory and the linearized...

Linearized plasticity is the evolutionary Γ -limit of finite plasticity

Alexander Mielke, Ulisse Stefanelli (2013)

Journal of the European Mathematical Society

We provide a rigorous justification of the classical linearization approach in plasticity. By taking the small-deformations limit, we prove via Γ -convergence for rate-independent processes that energetic solutions of the quasi-static finite-strain elastoplasticity system converge to the unique strong solution of linearized elastoplasticity.

Mathematical study of an evolution problem describing the thermomechanical process in shape memory alloys

Pierluigi Colli (1991)

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

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.

Modelled behaviour of granular material during loading and unloading

Krejčí, Pavel, Siváková, Lenka, Chleboun, Jan (2019)

Programs and Algorithms of Numerical Mathematics

The main aim of this paper is to analyze numerically the model behaviour of a granular material during loading and unloading. The model was originally proposed by D. Kolymbas and afterward modified by E. Bauer. For our purposes the constitutive equation was transformed into a rate independent form by introducing a dimensionless time parameter. By this transformation we were able to derive explicit formulas for the strain-stress trajectories during loading-unloading cycles and compare the results...

Numerical Modelling of Contact Elastic-Plastic Flows

N. M. Bessonov, S. F. Golovashchenko, V. A. Volpert (2009)

Mathematical Modelling of Natural Phenomena

Wilkins' method has been successfully used since early 60s for numerical simulation of high velocity contact elastic-plastic flows. The present work proposes some effective modifications of this method including more sophisticated material model including the Baushinger effect; modification of the algorithm based on correction of the initial configuration of a solid; a contact algorithm based on the idea of a mild contact.

On linear versus nonlinear flow rules in strain localization analysis

Giorgio Borré, Giulio Maier (1988)

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

This note contains some remarks on the analysis of bifurcation phenomena, specifically strain localization (onset of a strain rate discontinuity), in small-deformation elastoplasticity. Nonassociative flow rules are allowed for to cover constitutive models frequently adopted for frictional (and softening) materials such as concrete. The conventional derivation of the localization criterion resting on an incrementally linear "comparison material" is critically reviewed and compared to the criterion...

On Lyapunov stability in hypoplasticity

Kovtunenko, Victor A., Krejčí, Pavel, Bauer, Erich, Siváková, Lenka, Zubkova, Anna V. (2017)

Proceedings of Equadiff 14

We investigate the Lyapunov stability implying asymptotic behavior of a nonlinear ODE system describing stress paths for a particular hypoplastic constitutive model of the Kolymbas type under proportional, arbitrarily large monotonic coaxial deformations. The attractive stress path is found analytically, and the asymptotic convergence to the attractor depending on the direction of proportional strain paths and material parameters of the model is proved rigorously with the help of a Lyapunov function....

Rate independent Kurzweil processes

Pavel Krejčí, Matthias Liero (2009)

Applications of Mathematics

The Kurzweil integral technique is applied to a class of rate independent processes with convex energy and discontinuous inputs. We prove existence, uniqueness, and continuous data dependence of solutions in B V spaces. It is shown that in the context of elastoplasticity, the Kurzweil solutions coincide with natural limits of viscous regularizations when the viscosity coefficient tends to zero. The discontinuities produce an additional positive dissipation term, which is not homogeneous of degree...

Stress-controlled hysteresis and long-time dynamics of implicit differential equations arising in hypoplasticity

Victor A. Kovtunenko, Ján Eliaš, Pavel Krejčí, Giselle A. Monteiro, Judita Runcziková (2023)

Archivum Mathematicum

A long-time dynamic for granular materials arising in the hypoplastic theory of Kolymbas type is investigated. It is assumed that the granular hardness allows exponential degradation, which leads to the densification of material states. The governing system for a rate-independent strain under stress control is described by implicit differential equations. Its analytical solution for arbitrary inhomogeneous coefficients is constructed in closed form. Under cyclic loading by periodic pressure, finite...

The impact of uncertain parameters on ratchetting trends in hypoplasticity

Chleboun, Jan, Runcziková, Judita, Krejčí, Pavel (2023)

Programs and Algorithms of Numerical Mathematics

Perturbed parameters are considered in a hypoplastic model of granular materials. For fixed parameters, the model response to a periodic stress loading and unloading converges to a limit state of strain. The focus of this contribution is the assessment of the change in the limit strain caused by varying model parameters.

The relaxation of the Signorini problem for polyconvex functionals with linear growth at infinity

Jarosław L. Bojarski (2005)

Applicationes Mathematicae

The aim of this paper is to study the unilateral contact condition (Signorini problem) for polyconvex functionals with linear growth at infinity. We find the lower semicontinuous relaxation of the original functional (defined over a subset of the space of bounded variations BV(Ω)) and we prove the existence theorem. Moreover, we discuss the Winkler unilateral contact condition. As an application, we show a few examples of elastic-plastic potentials for finite displacements.

Currently displaying 1 – 20 of 20

Page 1