Open Access

L'université Paris Nanterre s'engage en faveur de l'Open Access

Par Open Access, on entend le libre accès aux résultats de la recherche, diffusés sous forme électronique et en ligne gratuitement. Ce mouvement existe au niveau mondial depuis la fin des années 90 et s'est concrétisé par des appels adressés à la communauté des chercheurs en faveur du partage des connaissances (Budapest, 2002 ; Berlin, 2003).

L'université Paris Nanterre favorise l'Open Access par le biais d'un portail HAL (Hyper Articles en Ligne), principale archive ouverte en France maintenue par le CNRS, qui rassemblent les publications des chercheurs affiliés à l'établissement. 

D'autres initiatives de Paris Nanterre contribuent au développement du Libre Accès, comme la participation des Presses Universitaires au projet OpenEdition Books, la diffusion de plusieurs revues en Open Access sur Revues.org, l'ouverture de carnets de recherche sur la plateforme Hypothèses par des chercheurs ou encore le projet Open Data de l'université.

Retrouvez sur ce site l'ensemble des informations disponibles sur l'open access à l'Université Paris Nanterre: renseignements pratiques, événements, tutoriels, ressources en ligne etc.

Les derniers dépôts de nos chercheurs !

  • [hal-01689922] Error bounds for the reliability index in finite element reliability analysis
    23 janvier 2018
    This work presents an extension of the goal-oriented error estimation techniques to the reliability analysis of a linear elastic structure. We use a first-order reliability method in conjunction with a finite element analysis (FEA) to compute the failure probability of the structure. In such a situation the output of interest that is computed from the FEA is the reliability index. The accuracy of this output, and thus of the reliability analysis, depends, in particular, on the accuracy of the FEA. In this paper, upper and lower bounds of the reliability index are proposed, as well as simple bounds of the failure probability. An application to linear fracture mechanics is presented.
  • [hal-01690130] An exergetic approach for materials fatigue
    23 janvier 2018
    An entropy approach has been recently developed, based on the irreversible thermodynamics and entropy production. It has been observed that, for low cycle fatigue, metals undergoing cyclic load reach fracture, at a certain level of entropy production called fracture fatigue entropy (FFE) (Naderi and Khonsari, 2010), solely dependent on the material. Until now, we only used the two principles of thermodynamics separately to follow the behaviour of a solid continuum problem as low cycle fatigue. We propose here to use the two laws of thermodynamics together via the Gouy-Stodola equation and the concept of exergy to provide a new description for metals undergoing low cycle fatigue.
  • [hal-01305736] A posteriori global error estimator based on the error in the constitutive relation for reduced basis approximation of parametrized linear elastic problems
    23 janvier 2018
    In this paper we introduce a posteriori error estimator based on the concept of error in the constitutive relation to verify parametric models computed with a reduced basis approximation. We develop a global error estimator which leads to an upper bound for the exact error and takes into account all the error sources: the error due to the reduced basis approximation as well as the error due to the finite element approximation. We propose an error indicator to measure the quality of the reduced basis approximation and we deduce an error indicator on the finite element approximation.
  • [hal-01421523] Features selection and classification to estimate elbow movements
    24 janvier 2018
    In this paper, we propose a novel method to estimate the elbow motion, through the features extracted from electromyography (EMG) signals. The features values are normalized and then compared to identify potential relationships between the EMG signal and the kinematic information as angle and angular velocity. We propose and implement a method to select the best set of features, maximizing the distance between the features that correspond to flexion and extension movements. Finally, we test the selected features as inputs to a non-linear support vector machine in the presence of non-idealistic conditions, obtaining an accuracy of 99.79% in the motion estimation results.
  • [hal-01237733] Estimation of the validity domain of hyper-reduction approximations in generalized standard elastoviscoplasticity
    23 janvier 2018
    Background We propose an a posteriori estimator of the error of hyper-reduced predictions for elastoviscoplastic problems. For a given fixed mesh, this error estimator aims to forecast the validity domain in the parameter space, of hyper-reduction approximations. This error estimator evaluates if the simulation outputs generated by the hyper-reduced model represent a convenient approximation of the outputs that the finite element simulation would have predicted. We do not account for the approximation error related to the finite element approximation upon which the hyper-reduction approximation is introduced. Methods We restrict our attention to generalized standard materials. Upon use of incremental variational principles, we propose an error in constitutive relation. This error is split into three terms including a tailored norm of the hyper-reduction approximation error. This error norm is defined by using the convexity of an incremental potential introduced to state the constitutive equations. The second term of the a posteriori error is related to the stress recovery technique that generates stresses fulfilling the finite element equilibrium equations. The last term is a coupling term between the hyper-reduction approximation error at each time step and the errors committed before this time step. Unfortunately, this last term prevents error certification. In this paper, we restrict our attention to outputs extracted by a Lipschitz function of the displacements. Results In the proposed numerical examples, we show very good preliminary results in predicting the validity domain of hyper-reduction approximations. The average computational time of the predictions obtained by hyper reduction, is accelerated by a factor of 6 compared to that of finite element simulations. This speed-up incorporates the computational time devoted to the error estimation. Conclusions The numerical implementation of the proposed error estimator is straightforward. It does not require the computation of the incremental potential. In the numerical results, the estimated validity domain of hyper-reduced approximations is inside the reference validity domain. This paper is a first attempt for a posteriori error estimation of hyper-reduction approximations.
  • [hal-01690027] A Posteriori Estimates for a Natural Neumann–Neumann Domain Decomposition Algorithm on a Unilateral Contact Problem
    23 janvier 2018
    In this paper we present an error estimator for unilateral contact problems solved by a Neumann–Neumann Domain Decomposition algorithm. This error estimator takes into account both the spatial error due to the finite element discretization and the algebraic error due to the domain decomposition algorithm. To differentiate specifically the contribution of these two error sources to the global error, two quantities are introduced: a discretization error indicator and an algebraic error indicator. The effectivity indices and the convergence of both the global error estimator and the error indicators are shown on several examples.
  • [hal-01421500] Numerical simulation of the coupling between thermal dissipation and fish-eye crack growth in very high cycle fatigue regime
    23 janvier 2018
    In this paper, we study the temperature field associated with the propagation of a fatigue crack in a very high cycle fatigue regime during ultrasonic fatigue testing. We use a Paris\textendashHertzberg crack growth law to compute the evolution of the crack and a perfectly elastic\textendashplastic constitutive law to compute the plastic dissipation per cycle at the tip of the crack. A thermomechanical finite element model is proposed to estimate the evolution of the temperature field during the crack propagation. Numerical results obtained agree fairly well with experimental results.
  • [hal-01421507] Error control in FORM reliability analysis
    23 janvier 2018
    This paper deals with the failure probability error induced by the coupling between the first-order reliability method (FORM) and the Finite Element Method (FEM). A FEM error estimator based on the concept of error in constitutive relation associated with goal-oriented error estimation is proposed. Furthermore an importance sampling technique is used to compute the error due to the FORM approximation. Both these errors are used to choose a finite element mesh adapted to the problem.
  • [hal-01689948] Optimization of Piezoelectric Sensors Location and Number Using a Genetic Algorithm
    23 janvier 2018
    In this article, the optimal location and number of piezoelec-tric sensors is formulated for active vibration control. A modified criterion is used to ensure good observability of the system by con-sidering the minimum number of needed piezoelectric elements. A genetic algorithm is proposed to solve this bi-objective optimization problem. Simulations are presented for a thin plate.
  • [hal-01689879] Optimal piezoelectric actuator and sensor location for active vibration control, using genetic algorithm
    23 janvier 2018
    This paper deals with the optimization of piezoelectric actuators and sensors locations for active vibration control. Two modified optimization criteria are used, ensuring good observability or controllability of the structure, and considering residual modes to limit the spillover effect. Two optimization variables are considered for each piezo-electric device: the location of its center and its orientation. Genetic algorithms are used to find the optimal configurations. Several simulations are presented for a simply supported plate.

Mis à jour le 08 décembre 2017