Recherche

Afficher tous les résultats pour Frictionless

Accueil

À propos
Confidentialité
Mentions légales

Graph Chatbot

Résultats de recherche

Frictionless

Concept

Intégrateur symplectique

Un intégrateur symplectique est une méthode numérique de résolution approchée des équations de la mécanique hamiltonienne, valable pour des faibles variations de temps. Les hypothèses de la mécanique hamiltonienne sont souvent appliquées à la mécanique céleste. Le système à étudier peut s'écrire sous la forme d'une action I et d'un angle φ, de manière que le système différentiel se réduise à : x := (I, φ) et : où l'on a noté : le crochet de Poisson de et . On voudrait connaître la solution formelle au système intégrable .

Concept

Équations de Lagrange

vignette|Joseph-Louis Lagrange Les équations de Lagrange, découvertes en 1788 par le mathématicien Joseph-Louis Lagrange, sont une reformulation de la mécanique classique. Il s'agit d'une reformulation de l'équation de Newton, qui ne fait pas intervenir les forces de réaction. Pour cela, on exprime les contraintes que subit la particule étudiée sous la forme d'équations du type : Il n'y a qu'une équation si le mouvement est contraint à une surface, deux s'il est contraint à une courbe.

Concept

Modèle du solide indéformable

Le modèle du solide indéformable est un modèle de solide fréquemment utilisé en mécanique des systèmes de points matériels. Il s'agit d'une idéalisation de la notion usuelle de corps (à l'état) solide, considéré comme absolument rigide, et négligeant toute déformation. Le solide indéformable est un modèle utilisé en mécanique pour décrire le comportement d'un corps (objet, pièce). Comme son nom l'indique, on considère qu'au cours du temps la distance entre deux points donnés ne varie pas.

Concept

Coordonnées généralisées

thumb|Calcul de vecteurs dans un système de coordonnées généralisées cartésien. On appelle coordonnées généralisées d'un système physique un ensemble de variables réelles, qui ne correspondent pas toutes à des coordonnées cartésiennes (par exemple : angles, positions relatives), et permettant de décrire ce système, en particulier dans le cadre de la mécanique lagrangienne. Le terme « généralisées » vient de l'époque où les coordonnées cartésiennes étaient considérées comme étant les coordonnées normales ou naturelles.

Concept

Rigid body dynamics

In the physical science of dynamics, rigid-body dynamics studies the movement of systems of interconnected bodies under the action of external forces. The assumption that the bodies are rigid (i.e. they do not deform under the action of applied forces) simplifies analysis, by reducing the parameters that describe the configuration of the system to the translation and rotation of reference frames attached to each body. This excludes bodies that display fluid, highly elastic, and plastic behavior.

Concept

Deformation (engineering)

In engineering, deformation refers to the change in size or shape of an object. Displacements are the absolute change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain is the relative internal change in shape of an infinitesimally small cube of material and can be expressed as a non-dimensional change in length or angle of distortion of the cube. Strains are related to the forces acting on the cube, which are known as stress, by a stress-strain curve.

Publication

From low-rank retractions to dynamical low-rank approximation and back

Daniel Kressner, Axel Elie Joseph Séguin, Gianluca Ceruti

In algorithms for solving optimization problems constrained to a smooth manifold, retractions are a well-established tool to ensure that the iterates stay on the manifold. More recently, it has been demonstrated that retractions are a useful concept for ot ...

Springer2024

Publication

Pseudo-Three-Dimensional Analytical Model of Linear Induction Motors for High-Speed Applications

Mario Paolone, André Hodder, Lucien André Félicien Pierrejean, Simone Rametti

Literature on linear induction motors (LIMs) has proposed several approaches to model the behavior of such devices for different applications. In terms of accuracy and fidelity, field analysis-based models are the most relevant. Closed-form or numerical so ...

2024

Publication

Computational Homogenization for Inverse Design of Surface-based Inflatables

Mark Pauly, Florin Isvoranu, Uday Kusupati, Seiichi Eduardo Suzuki Erazo, Yingying Ren, Francis Julian Panetta

Surface-based inflatables are composed of two thin layers of nearly inextensible sheet material joined together along carefully selected fusing curves. During inflation, pressure forces separate the two sheets to maximize the enclosed volume. The fusing c ...

2024

Publication

Analytical Model of Single-Sided Linear Induction Motors for High-Speed Applications

Mario Paolone, André Hodder, Lucien André Félicien Pierrejean, Simone Rametti

This article describes a field-based analytical model of single-sided linear induction motors (SLIMs) that explicitly considers the following effects altogether: finite motor length, magnetomotive force mmf space harmonics, slot effect, edge effect, and ta ...

IEEE2024

Publication

A review of wave celerity in frictionless and axisymmetrical steel-lined pressure tunnels

Anton Schleiss, Fadi Hachem

Generally applicable approaches for estimating the‘‘quasi-static’’, which means without fluid–structure interaction and frequency-dependent water-hammer wave speed in steel-lined pressure tunnels are analyzed. The external constraints and assumptions of th ...

Elsevier2011

Publication

Modeling friction and wear using an adaptive discrete-continuum coupling

Manon Eugénie Voisin--Leprince

When two objects slide against each other, wear and friction occur at their interface. The accumulation of wear forms what is commonly referred to as a ``third-body''. Understanding third-body evolution has significant applications in industry, where contr ...

EPFL2024

Publication

Estimation of the bar stress based on crack width measurements in reinforced concrete structures

Aurelio Muttoni, Enrique Corres Sojo

Estimating the stress of reinforcing bars and its variations in service conditions can be useful to determine the reserve capacity of structures or to assess the risk of fatigue in the reinforcement. This paper investigates the use crack width measurements ...

Ernst & Sohn2024

Instabilities in Elastic and Magneto-Elastic Beams and Shells: from Shell Buckling to the Design of a Programmable Braille Reader

Arefeh Abbasi

In this thesis, we conduct a comprehensive investigation into structural instabilities of both elastic and magneto-elastic beams and shells, resulting in a creative proposal to design a programmable braille reader. Methodologically, we combine numerical si ...

EPFL2024

Publication

Experimental Investigation on Size-Effect of Rubble Stone Masonry Walls Under In-Plane Horizontal Loading: Overview and Preliminary Results

Katrin Beyer, Savvas Saloustros

Rubble stone masonry is a common construction typology of historical city centres and vernacular architecture. While past earthquakes have shown that it is one of the most vulnerable masonry construction typologies, there are few experimental campaigns giv ...

2024

Publication

Adaptive Finite Elements with Large Aspect Ratio. Application to Aluminium Electrolysis

Paride Passelli

The goal of this work is to use anisotropic adaptive finite elements for the numerical simulation of aluminium electrolysis. The anisotropic adaptive criteria are based on a posteriori error estimates derived for simplified problems. First, we consider an ...

EPFL2024

Publication

Dataset for "Complexity of crack front geometry enhances toughness of brittle solids"

John Martin Kolinski, Chenzhuo Li, Xinyue Wei

This data package supports the publication 'Complexity of crack front geometry enhances toughness of brittle solids' by Xinyue Wei, Chenzhuo Li, Cían McCarthy, and John M. Kolinski Nature physics (2024) - https://doi.org/10.1038/s41567-024-02435-x DOI: 1 ...

Zenodo2024

Publication

A multisymplectic integrator for elastodynamic frictionless impact problems

Tudor Ratiu, François Gay-Balmaz, François Marie Alain Demoures, Alejandro Marcos Aragon, Mathieu Desbrun

We present a structure preserving numerical algorithm for the collision of elastic bodies. Our integrator is derived from a discrete version of the field-theoretic (multisymplectic) variational description of nonsmooth Lagrangian continuum mechanics, combi ...

Elsevier2017

Publication

A cut-cell method for the numerical simulation of 3D multiphase flows with strong interfacial effects

Marco Picasso, Alexandre Caboussat, Julien Hess, Alexandre Masserey

We present a numerical model for the approximation of multiphase flows with free surfaces and strong interfacial effects. The model relies on the multiphase incompressible Navier-Stokes equations, and includes surface tension effects on the interfaces betw ...

Academic Press Inc Elsevier Science2024

The time-domain Cartesian multipole expansion of electromagnetic fields

Farhad Rachidi-Haeri, Marcos Rubinstein, Elias Per Joachim Le Boudec, Nicolas Mora Parra, Chaouki Kasmi, Emanuela Radici

Time-domain solutions of Maxwell’s equations in homogeneous and isotropic media are paramount to studying transient or broadband phenomena. However, analytical solutions are generally unavailable for practical applications, while numerical solutions are co ...

Nature Publishing Group2024