An open question : How to solve efficiently 3D frictional contact problem ?

International audienceIn this talk, we want to discuss possible numerical solution procedures for the following discrete frictional contact problem. We will recall a result for the problem in (1) which ensures that a solution exists [3]. In this framework, we will list several algorithms that have been previously developed for solving the SOCCP (1) mainly based variational inequality and nonsmooth equations reformulations. On one hand, we will show that algorithms based on Newton methods for nonsmooth equations solve quickly the problem when they succeed, but suffer from robustness issues mainly if the matrix H has not full rank. On the other hand, the iterative methods dedicated to solving variational inequalities are quite robust but with an extremely slow rate of convergence. To sum up, as far as we know there is no option that combines time efficiency and robustness. To try to answer to this question, we develop an open collection of discrete frictional contact problems called FCLIB http://fclib.gforge.inria.fr in order to offer a large library of problems to compare algorithms on a fair basis. In this work, this collection is solved with the software Siconos and its component Siconos/Numerics http://siconos.gforge.inria.fr

An open question : How to solve efficiently 3D frictional contact problem ?

International audienceIn this talk, we want to discuss possible numerical solution procedures for the following discrete frictional contact problem. We will recall a result for the problem in (1) which ensures that a solution exists [3]. In this framework, we will list several algorithms that have been previously developed for solving the SOCCP (1) mainly based variational inequality and nonsmooth equations reformulations. On one hand, we will show that algorithms based on Newton methods for nonsmooth equations solve quickly the problem when they succeed, but suffer from robustness issues mainly if the matrix H has not full rank. On the other hand, the iterative methods dedicated to solving variational inequalities are quite robust but with an extremely slow rate of convergence. To sum up, as far as we know there is no option that combines time efficiency and robustness. To try to answer to this question, we develop an open collection of discrete frictional contact problems called FCLIB http://fclib.gforge.inria.fr in order to offer a large library of problems to compare algorithms on a fair basis. In this work, this collection is solved with the software Siconos and its component Siconos/Numerics http://siconos.gforge.inria.fr

Exomars Rover Mechanical Modeling with Siconos

This document contains specification and documentation of the tests performed on the exomars planetary rover model using Siconos software. Siconos is an open source scientific software targeted at modeling and simulating nonsmooth dynamical systems. The advantage of using Siconos for mechanical simulations is that it offers efficient friction-contact nonsmooth models. Performing mechanical simulations of the exomars rover appears to be of great importance with respect to verifying its design and estimating energy consumption. Seven different scenarios have been defined in order to simulate the mechanical behaviour of the exomars rover. Dynamics and kinematics models of the exomars rover have been created using HuMAnS software and implemented inside Siconos using its C code generator as plugin functions. The intention of this report is to create a common reference and unification of mechanical tests of the exomars rover across different simulation platforms

Sur la résolution du problème de frottement tridimensionnel : Formulations et comparaisons des méthodes numériques

In this report, we review several formulations of the discrete frictional contact problemthat arises in space and time discretized mechanical systems with unilateral contact andthree-dimensional Coulomb’s friction. Most of these formulations are well–known concepts in theoptimization community, or more generally, in the mathematical programming community. Tocite a few, the discrete frictional contact problem can be formulated as variational inequalities,generalized or semi–smooth equations, second–order cone complementarity problems, or as optimizationproblems such as quadratic programming problems over second-order cones. Thanks tothese multiple formulations, various numerical methods emerge naturally for solving the problem.We review the main numerical techniques that are well-known in the literature and we also proposenew applications of methods such as the fixed point and extra-gradient methods with self-adaptivestep rules for variational inequalities or the proximal point algorithm for generalized equations.All these numerical techniques are compared over a large set of test examples using performanceprofiles. One of the main conclusion is that there is no universal solver. Nevertheless, we are ableto give some hints to choose a solver with respect to the main characteristics of the set of testsDans ce rapport, plusieurs formulations du problème discret de contact frottant qui apparaîtdans les systèmes mécaniques avec du contact unilatéral et du frottement de Coulomb, sont présentées.La plupart de ces formulations sont des objets bien connus dans la communauté de l’optimisation, etplus généralement, de la programmation mathématique. Pour en citer quelques uns, le problème decontact frottant peut être formulé comme une inégalité variationnelle, comme une équation non-régulièreou semi–lisse, comme un problème de complémentarité sur des cônes, ou encore comme des problèmesd’optimisation par exemple des problèmes quadratiques sur des cônes du second ordre. Grâce à cesmultiples formulations, de nombreuses méthodes numériques de résolutions émergent naturellement. Ondétaille dans ce rapport les principales techniques numériques bien connues dans la littérature et nousproposons aussi des nouvelles méthodes comme les méthodes de point fixe et d’extra-gradient pour lesinégalités variationnelles avec une règle d’adaptation automatique du pas, ainsi que l’application del’algorithme du point optimal pour les équations généralisées. Toutes ces techniques sont comparées surun grand ensemble de problème–tests en utilisant des profils de performance. Une des conclusions est qu’iln’existe pas de méthode universelle. Néanmoins, on peut donner des conseils pour choisir une méthodeparticulière la mieux adaptée aux caractéristiques d’un problème donné

Méthodes de Newton non–lisses pour les problèmes de contact frottant dans les systèmes de multi–corps flexibles

International audienceDans cette contribution, on se propose d’évaluer la performance des méthodes de Newton non–lisses dans le contexte des systèmes multi–corps flexibles (mécanismes, milieux granulaires ou milieux divisés) avec contact et frottement. Les méthodes itératives de type projection (Jacobi ou Gauss-Seidel projeté) sont généralement utilisées pour leurs propriétés de robustesse et de régularisation des systèmes fortement hyper–statiques. On montre que dans le cas des systèmes déformables, les méthodes de Newton permettent d’atteindre de grandes précisions à un coût beaucoup plus faible

FCLIB: a collection of discrete 3D Frictional Contact problems

The goal of this work is to set up a collection of 3D Frictional Contact (3DFC) problems. The collection will provide a standard framework for testing available and new algorithms for solving discrete frictional contact problems. In this document, we describe the mathematical problems that we want to collect and the contents of the current collection

Exomars Rover Mechanical Modeling with Siconos

This document contains specification and documentation of the tests performed on the exomars planetary rover model using Siconos software. Siconos is an open source scientific software targeted at modeling and simulating nonsmooth dynamical systems. The advantage of using Siconos for mechanical simulations is that it offers efficient friction-contact nonsmooth models. Performing mechanical simulations of the exomars rover appears to be of great importance with respect to verifying its design and estimating energy consumption. Seven different scenarios have been defined in order to simulate the mechanical behaviour of the exomars rover. Dynamics and kinematics models of the exomars rover have been created using HuMAnS software and implemented inside Siconos using its C code generator as plugin functions. The intention of this report is to create a common reference and unification of mechanical tests of the exomars rover across different simulation platforms

Mechanical simulation of the Exomars rover using Siconos in 3DROV

International audienceThis paper presents ongoing work at INRIA in collaboration with TRASYS on the mechanical modelling and simulation of planetary rovers. We focus our presentation on an specific approach used the INRIA SICONOS software. This approach [2] based on the nonsmooth Mechanics theory is dedicated to the modeling and the simulation of multi-body systems with joints, hard contacts, Coulomb's friction and impacts. In addition, software integration aspects are considered defining and implementing generic software interfaces between SICONOS and external 3D tools. The approach is applied to the rover planetary operations enhancing the fidelity and the genericity of the ExoMars existing rover mechanical model

Expérimentation d'une plate-forme de portage logiciel à l'INRIA

National audienceAu sein de l'INRIA, les équipes projets qui développent des logiciels scientifiques sont confrontées, dès lors qu'elles veulent les distribuer, au portage sur une multiplicité d'environnements matériels et logiciels en constante évolution. Les tâches de portage logiciel sont réalisées par l'intermédiaire de leurs propres parcs de machines hétérogènes qui posent des problèmes d'hébergement, d'administration système et de maintenance. Les configurations spécifiques sur de nombreuses combinaisons possibles d'architectures et de systèmes ne permettent pas d'envisager une solution de mutualisation à partir de serveurs de connexion classiques. PIPOL (Plate-forme Inria de POrtage Logiciel) est une expérimentation d'un service de portage pour les logiciels scientifiques à l'échelle de l'INRIA. Les ressources matérielles sont partagées et disponibles après réservation et déploiement du système d'exploitation souhaité. Un service permet la configuration automatique des systèmes, la planification et le traitement de travaux utilisateurs

An introduction to Siconos

In this document, a brief overview of the Siconos Platform is given. One of the goal is to give a flavor on a simple example of the ability of the platform to model and simulate the so-called non smooth dynamical systems (NSDS). In particular, some examples of Lagrangian mechanical systems with contact and friction or electrical circuits with ideal and piecewise linear components (diodes, MOS transistors, \ldots) are commented. Finally, the Siconos software is presented, starting from its architecture to a non exhaustive presentation of its components and functionalities. The aim of this document is not to serve as a reference guide but more as a illustrative introduction document to promote the use of the platform