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See detailFinite Element Computation of Nonlinear Normal Modes
Renson, Ludovic ULg; Deliège, Geoffrey ULg; Noels, Ludovic ULg et al

in Fifth International Conference on Advanced COmputational Methods in ENgineering (2011)

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See detailFinite element computation of nonlinear normal modes of nonconservative systems
Renson, Ludovic ULg; Deliège, Geoffrey ULg; Kerschen, Gaëtan ULg

in Proceedings of the ISMA 2012 conference (2012, September)

Modal analysis, i.e., the computation of vibration modes of linear systems, is really quite sophisticated and advanced. Even though modal analysis served, and is still serving, the structural dynamics ... [more ▼]

Modal analysis, i.e., the computation of vibration modes of linear systems, is really quite sophisticated and advanced. Even though modal analysis served, and is still serving, the structural dynamics community for applications ranging from bridges to satellites, it is commonly accepted that nonlinearity is a frequent occurrence in engineering structures. Because modal analysis fails in the presence of nonlinear dynamical phenomena, the development of a practical nonlinear analog of modal analysis is the objective of this research. Progress in this direction has been made recently with the development of numerical techniques (harmonic balance, continuation of periodic solutions) for the computation of nonlinear normal modes (NNMs). Because these methods consider the conservative system, this study targets the computation of NNMs for nonconservative systems, i.e. defined as invariant manifolds in phase space. Specifically, a new finite element technique is proposed to solve the set of partial differential equations governing the manifold geometry. The algorithm is demonstrated using different two-degree-of-freedom systems. [less ▲]

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See detailFinite Element Computational Homogenization for Heterogeneous Materials in Magnetodynamics
Niyonzima, Innocent ULg; Vazquez Sabariego, Ruth ULg; Dular, Patrick ULg et al

in Proceedings of the Fifth International Conference on Advanced COmputational Methods in ENgineering (ACOMEN 2011) (2011, November)

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See detailFinite Element Computational Homogenization of Nonlinear Multiscale Materials in Magnetostatics
Niyonzima, Innocent ULg; V Sabariego, Ruth ULg; Dular, Patrick ULg et al

in 18th Conference on the Computation of Electromagnetic Fields (COMPUMAG2011) (2011)

This paper deals with the modelling of nonlinear multiscale materials in magnetostatics by means of a finite element computational homogenization method. The method couples a macroscale problem with many ... [more ▼]

This paper deals with the modelling of nonlinear multiscale materials in magnetostatics by means of a finite element computational homogenization method. The method couples a macroscale problem with many microscale problems. During the upscaling step, the homogenized magnetic permeability and its derivative with respect to the magnetic field are calculated from the microscale solution and transferred to the macroscale. The downscaling step consists in imposing proper boundary conditions for the microscale problems from the macroscale solution. Results are validated by comparison with those obtained with classical finite element brute force approach. [less ▲]

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See detailFinite Element Computational Homogenization of Nonlinear Multiscale Materials in Magnetostatics
Niyonzima, Innocent ULg; V Sabariego, Ruth ULg; Dular, Patrick ULg et al

in IEEE Transactions on Magnetics (2012), 48(2), 587-590

The increasing use of composite materials in the technological industry (automotive, aerospace, ...) requires the development of effective models that account for the complexity of the microstructure of ... [more ▼]

The increasing use of composite materials in the technological industry (automotive, aerospace, ...) requires the development of effective models that account for the complexity of the microstructure of these materials and the nonlinear behaviour they can exhibit. In this paper we develop a multiscale computational homogenization method for modelling nonlinear multiscale materials in magnetostatics based on the finite element method. The method solves the macroscale problem by getting data from certain microscale problems around some points of interest. The missing nonlinear constitutive law at the macroscale level is derived through an upscaling from the microscale solutions. The downscaling step consists in imposing a source term and determining proper boundary conditions for microscale problems from the macroscale solution. For a two-dimensional geometry, results are validated by comparison with those obtained with a classical brute force finite element approach and a classical homogenization technique. The method provides a good overall macroscale response and more accurate local data around points of interest. [less ▲]

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See detailFinite Element Discretizations to Evaluate Electrostatic Forces Around Corners
Hannot, Stephan; Rixen, Daniel; Rochus, Véronique ULg

(2007)

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See detailA finite element for thermo-mechanical problems.
Bourdouxhe, Michel; Charlier, Robert ULg; Cescotto, Serge ULg

in Proceedings Numiform Conference Göteborg (1986, August)

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See detailFinite element formulation and couplings
Habraken, Anne ULg; Collin, Frédéric ULg

Conference (2013)

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See detailA finite element formulation for spectral problems in optical fibers
Guenneau, S.; Nicolet, A.; Zolla, F. et al

in COMPEL (2001), 20(1), 120--131

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See detailFinite element grid optimization with geometric approach
Hwang, H. T.; Fleury, Claude ULg

in The 33rd Aiaa/Asme/Asce/Ahs/Asc Structures, Structural Dynamics and Materials Conference: April 13-15, 1992/Dallas, Tx (1992)

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See detailFinite element investigation of size effects on the mechanical behavior of nickel single crystals
Keller, Clément; Habraken, Anne ULg; Duchene, Laurent ULg

in Materials Science & Engineering : A (2012), 550(30), 342-349

The influence of dimensions on the mechanical behavior of f.c.c. single crystals with dimensions larger than a few micrometers has been the topic of many experimental investigations and controversies ... [more ▼]

The influence of dimensions on the mechanical behavior of f.c.c. single crystals with dimensions larger than a few micrometers has been the topic of many experimental investigations and controversies during the 1970s and this question is still open. The objective of this article is to shed new light on this point by performing finite element simulations thanks to a strain gradient crystal plasticity model. Based on the model identification for nickel, several single crystal samples with various thicknesses and orientations were tested numerically in tension. The effect of dimensions was then analyzed considering the spatial distribution of dislocation densities. Near loading boundaries, dislocation density gradients appeared perpendicular to the Burgers vector direction of the primary activated slip system which modified the mechanical behavior. These gradients are discussed in terms of boundary conditions, crystal orientation and dislocation interactions with surfaces. [less ▲]

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See detailFinite Element Magnetic Models via a Coupling of Subproblems of Lower Dimensions
Dular, Patrick ULg; V Sabariego, Ruth ULg; Geuzaine, Christophe ULg et al

in IEEE Transactions on Magnetics (2010), 46(8), 2827-2830

Model refinements of magnetic circuits are performed via a subdomain finite element method based on a perturbation technique. A complete problem is split into subproblems, some of lower dimensions, to ... [more ▼]

Model refinements of magnetic circuits are performed via a subdomain finite element method based on a perturbation technique. A complete problem is split into subproblems, some of lower dimensions, to allow a progression from 1-D to 3-D models. Its solution is then expressed as the sum of the subproblem solutions supported by different meshes. A convenient and robust correction procedure is proposed allowing independent overlapping meshes for both source and reaction fields, the latter being free of cancellation error in magnetic materials. The procedure simplifies both meshing and solving processes, and quantifies the gain given by each model refinement on both local fields and global quantities. [less ▲]

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See detailA finite element method for poro mechanical modelling of geotechnical problems using local second gradient models
Collin, Frédéric ULg; Chambon, René; Charlier, Robert ULg

in International Journal for Numerical Methods in Engineering (2006), 65(11), 1749-1772

In this paper, a new finite element method is described and applied. It is based on a theory developed to model poromechanical problems where the mechanical part is obeying a second gradient theory. The ... [more ▼]

In this paper, a new finite element method is described and applied. It is based on a theory developed to model poromechanical problems where the mechanical part is obeying a second gradient theory. The aim of such a work is to properly model the post localized behaviour of soils and rocks saturated with a pore fluid. Beside the development of this new Coupled theory, a corresponding finite element method has been developed. The elements used are based on a weak form of the relation between the deformation gradient and the second gradient, using a field of Lagrange multipliers. The global problem is solved by a system of equations where the kinematic variables are fully coupled with the pore pressure. Some numerical experiments showing the effectiveness of the method ends the paper. Copyright (c) 2005 John Wiley [less ▲]

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See detailFinite element model for the extension of the direct strength method to hot-rolled profile cross-sections
Li, Yongzhen ULg; Rossi, Barbara ULg

in Proceedings of the 12th Nordic Steel Construction Conference (2012, September 05)

Abstract: In the present research, a geometrically and materially nonlinear analysis using the FE method has been conducted to evaluate the resistance of axially compressed hot-rolled H profile cross ... [more ▼]

Abstract: In the present research, a geometrically and materially nonlinear analysis using the FE method has been conducted to evaluate the resistance of axially compressed hot-rolled H profile cross-sections. The FE model was firstly duly verified against experimental data and then used to carry a parametric analysis. The goal of the analysis is to propose a new Direct Strength Method (DSM) strength curve intended for calculating the resistance of non-compact and slender hot-rolled H profile cross-sections. [less ▲]

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See detailFinite Element Model Updating Based On Holographic and Speckle Interferometry Measurements: Rapport VIA-25
Simon, Daniel; Golinval, Jean-Claude ULg

Conference given outside the academic context (1999)

Optical measurement techniques look very promising for finite element (F.E.) model updating or error localisation of plate-like structures in the field of structural dynamics. The purpose of this paper is ... [more ▼]

Optical measurement techniques look very promising for finite element (F.E.) model updating or error localisation of plate-like structures in the field of structural dynamics. The purpose of this paper is to investigate a way to better exploit the high spatial resolution inherent to these techniques in order to correct FE mesh discretisation errors and/or model parameter errors. An important assumption in F.E. model error detection is first to consider the initial mesh as sufficiently fine to well represent the measured (displacement or stress) field. In the case of model updating, the adjustment of the model is performed by minimising the difference between the outputs of the model and the exact solution with respect to design parameters. In the case of FE mesh adaptation, the exact solution has to be estimated whereas in the case of model parameter errors, it is directly measured. The idea developed in this paper is to take advantage of the high spatial resolution offered by optical techniques to calculate successively two error estimators using only measurements. The experimental field is first used for the detection of singular regions corresponding to high gradients. This estimator indicates the regions where a mesh refinement is required. Thus a second estimator is calculated and used for parameter error detection. [less ▲]

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See detailFinite Element Model Updating of Plate-like Structures Using Modal Holographic Measurement Field
Simon, Daniel; Golinval, Jean-Claude ULg

Conference given outside the academic context (2002)

Optical measurement techniques are very promising for finite element (F.E.) model updating or error localisation of plate-like structures in the field of structural dynamics. The purpose of this work is ... [more ▼]

Optical measurement techniques are very promising for finite element (F.E.) model updating or error localisation of plate-like structures in the field of structural dynamics. The purpose of this work is to investigate a way to better exploit the high spatial resolution inherent to these techniques in order to correct FE mesh discretisation errors and/or model parameter errors. An important assumption in F.E. model error detection is first to consider the initial mesh as sufficiently fine to well represent the measured (displacement or stress) field. In the case of model updating, the adjustment of the model is performed by minimising the difference between the outputs of the model and the exact solution with respect to design parameters. In the case of FE mesh adaptation, the exact solution has to be estimated whereas in the case of model parameter errors, the reference solution is assumed to be the measured one. The idea developed in this paper is to take advantage of the high spatial resolution offered by optical techniques to calculate successively two error estimators using only measurements. The experimental field is first used for the detection of singular regions corresponding to high gradients. This estimator indicates the regions where a mesh refinement is required. Thus a second estimator is calculated and used for parameter error detection. [less ▲]

Detailed reference viewed: 25 (1 ULg)
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See detailFinite Element Model Updating of the Garteur SM-AG19 Structure
Thonon, Carole; Golinval, Jean-Claude ULg

Conference given outside the academic context (2001)

This paper reports the procedure followed by the "LTAS-Vibrations et Identification des Structures" research group to generate a low order nite element (F.E.) model of the GARTEUR SM-AG19 structure ... [more ▼]

This paper reports the procedure followed by the "LTAS-Vibrations et Identification des Structures" research group to generate a low order nite element (F.E.) model of the GARTEUR SM-AG19 structure proposed as benchmark in the framework of the European COST Action F3 in structural dynamics. The model is made of beam elements, local inertia and rigid body elements. First, the correlation of the experimental data with the results of the F.E. model shows different levels of discrepancies. To perform local error detection, the size of the measured mode shape vectors is first expanded to the size of the F.E. eigenvectors. Model error localisation is based on the computation of residual strain energy due to errors in the constitutive equations. Updating parameters are then selected using eigenvalue sensitivity and local error analyses. The error localisation procedure is followed by the updating process in order to improve the accuracy of the FE models. The quality of the results is assessed in terms of accuracy of the response prediction to structural modifications. [less ▲]

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See detailFinite element modeling of an electrostatic painting device
Deliège, Geoffrey ULg; Henrotte, François; Hameyer, Kay

in IEEE Transactions on Magnetics (2003), 39(3), 1432-1435

Detailed reference viewed: 9 (1 ULg)