References of "Masset, Luc"
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See detailThe Harmonic Balance Method for Bifurcation Analysis of Nonlinear Mechanical Systems
Detroux, Thibaut ULg; Renson, Ludovic ULg; Masset, Luc ULg et al

in Proceedings of the SEM IMAC XXXIII (2015)

Because nowadays structural engineers are willing to use or at least understand nonlinearities instead of simply avoiding them, there is a need for numerical tools performing analysis of nonlinear large ... [more ▼]

Because nowadays structural engineers are willing to use or at least understand nonlinearities instead of simply avoiding them, there is a need for numerical tools performing analysis of nonlinear large-scale structures. Among these techniques, the harmonic balance (HB) method is certainly one of the most commonly used to study finite element models with reasonably complex nonlinearities. However, in its classical formulation the HB method is limited to the approximation of periodic solutions. For this reason, the present paper proposes to extend the method to the detection and tracking of codimension-1 bifurcations in the system parameters space. As an application, the frequency response of a spacecraft is studied, together with two nonlinear phenomena, namely quasiperiodic oscillations and detached resonance curves. This example illustrates how bifurcation tracking using the HB method can be employed as a promising design tool for detecting and eliminating such undesired behaviors. [less ▲]

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See detailEnhancement of ray tracing method for radiative heat transfer: application to EUI space instrument
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Proceedings of the 15th International Heat Transfer Conference, IHTC-15 (2014, August)

The finite element method (FEM) is widely used in mechanical engineering, in particular for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, in particular for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs), used to calculate radiative thermal exchanges in space, are usually computed through Monte Carlo ray tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. The isocell method aims at reducing the computational effort of the REFs with FEM, by decreasing the number of rays required to achieve a given accuracy. Based on Nusselt’s analogy, the ray direction sampling is carried out by sampling the unit disc to derive the ray directions. The isocell method is a special case of stratified sampling. It divides the unit disc into cells of almost same area and shape from which random points are generated. This enhances the uniformity of the ray directions and leads to faster convergence. This isocell method is associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard thermal analysis ray tracing engine used in the European aerospace industry. One entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developedat the Centre Spatial de Liège in Belgium is used as benchmarking case. Solar Orbiter is an European Space Agency mission to be launched in a Sun-centered 0.28 perihelion orbit. [less ▲]

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See detailEnhancement of ray tracing method for radiative heat transfer with new isocell quasi-monte carlo technique and application to EUI space instrument
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Proceedings of the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, HEFAT2014 (2014, July)

Monte Carlo ray tracing method for thermal analysis. The rationale for this research is the speed-up of radiative heat transfer computation with the Finite Element Method, widely used in mechanical ... [more ▼]

Monte Carlo ray tracing method for thermal analysis. The rationale for this research is the speed-up of radiative heat transfer computation with the Finite Element Method, widely used in mechanical engineering especially for space structure design but not yet often for thermal analysis of these structures. Based on Nusselt’s analogy, the ray direction sampling is done by sampling the unit disc to derive the ray directions. Stratified sampling is applied to the unit disc that is divided into cells or strata into which random points are generated. The isocell method relies on cells that have the particularity of presenting almost the same area and shape. This enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. The isocell method is associated with different surface sampling to derive REFs. The method is benchmarked against ESARAD, the standard ray tracing engine of the thermal analysis software used in the European aerospace industry. Various geometries are used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is presented. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a 0.28 perihelion orbit around the Sun in 2018. [less ▲]

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See detailRay tracing enhancement for space thermal analysis: isocell method
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

in Sarler, Bozidar; Massaroti, Nicola; Nithiarasu, Perumal (Eds.) Third International Conference on Computational Methods for Thermal Problems (2014, June 02)

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs) are usually computed through Monte Carlo ray-tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. The developments of the new Isocell quasi-Monte Carlo ray tracing method are presented. The Isocell method enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. It is associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard ray-tracing engine for thermal analysis used in the European aerospace industry. Various geometries are used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is used. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a Sun-centered 0.28 perihelion orbit in 2018. [less ▲]

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See detailRay tracing enhancement for space thermal analysis: isocell method
Jacques, Lionel ULg; Masset, Luc ULg; Kerschen, Gaëtan ULg

Conference (2013, December 04)

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, especially for space structure design. However, FEM is not yet often used for thermal engineering of space structures where the lumped parameter method is still dominant. Radiative exchange factors (REFs), used to calculate radiative thermal exchanges in space, are usually computed through Monte Carlo ray-tracing. Due to the large number of elements composing a FE model, the computation of the REFs is prohibitively expensive. In the frame of a global approach, several research axes will be investigated to reduce the computational effort of the REFs with FEM. The first one focuses on accelerating the convergence and enhancing the accuracy of the ray-tracing process to decrease the number of rays required to achieve a given accuracy. The developments of the new Isocell quasi-Monte Carlo ray tracing method are presented. Based on Nusselt’s analogy, the ray direction sampling is carried out by sampling the unit disc to derive the ray directions. The unit disc is divided into cells into which random points are then generated. The cells have the particularity of presenting almost the same area and shape. This enhances the uniformity of the generated quasi-random sequence of ray directions and leads to faster convergence. This Isocell method has been associated with different surface sampling to derive the REFs. The method is benchmarked against ESARAD, the standard thermal analysis software used in the European aerospace industry. Various geometries have been used. In particular, one entrance baffle of the Extreme Ultraviolet Imager (EUI) instrument developed at the Centre Spatial de Liège in Belgium is used. The EUI instrument of the Solar Orbiter European Space Agency mission and will be launched in a Sun-centered (0.28 perihelion) orbit in 2018. [less ▲]

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See detailPartition of the circle in cells of equal area and shape
Masset, Luc ULg

Report (2011)

In the present paper, a new method for partitioning a circle in cells is presented. Cells have equal areas and shapes, so the method is termed the Isocell method. Its most interesting property is that ... [more ▼]

In the present paper, a new method for partitioning a circle in cells is presented. Cells have equal areas and shapes, so the method is termed the Isocell method. Its most interesting property is that cell centres are uniformly distributed inside the circle. Among possible applications of the Isocell method, the calculation of view factors by ray-tracing (image rendering, radiative heat transfer modelling) is presented. [less ▲]

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See detailThermal model reduction using the super-face concept
Masset, Luc ULg; Bruls, Olivier ULg; Kerschen, Gaëtan ULg

Conference (2011)

The objective of this presentation is to carry out thermal model reduction in the context of the finite element method. The finite element model is decomposed in several sets of adjacent faces called ... [more ▼]

The objective of this presentation is to carry out thermal model reduction in the context of the finite element method. The finite element model is decomposed in several sets of adjacent faces called super-faces. Specialized algorithms such as the METIS partitioning algorithm are used to automatically generate the super-faces. Several constraints may be imposed, e.g., the size of the super-face, its aspect ratio or its aperture angle. Once the model is decomposed, view factors between super-faces are calculated with direct numerical integration or ray-tracing methods. This method offers a very substantial reduction of the computational burden compared to the full model, which is particularly interesting for pre-design studies or specific applications such as deployable structures. [less ▲]

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See detailProper Orthogonal Decomposition for Nonlinear Radiative Heat Transfer Problems
Hickey, D.; Masset, Luc ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the ASME International Design Engineering Technical Conferences (2011)

Analysing large scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally very expensive ... [more ▼]

Analysing large scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally very expensive, especially if the number of degrees-of-freedom is high. This paper develops modal reduction techniques for such nonlinear multiphysical systems. The paper focuses on Proper Orthogonal Decomposition (POD), a multivariate statistical method that obtains a compact representation of a data set by reducing a large number of interdependent variables to a much smaller number of uncorrelated variables. A fully coupled, thermomechanical model consisting of a multilayered, cantilever beam is described and analysed. This linear benchmark is then extended by adding nonlinear radiative heat exchanges between the beam and an enclosing box. The radiative view factors, present in the equations governing the heat fluxes between beam and box elements, are obtained with a raytracing method. A reduction procedure is proposed for this fully coupled nonlinear, multiphysical, thermomechanical system. Two alternative approaches to the reduction are investigated, a monolithic approach incorporating a scaling factor to the equations, and a partitioned approach that treats the individual physical modes separately. The paper builds on previous work presented previously by the authors. The results are given for the RMS error between either approach and the original, full solution. [less ▲]

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See detailInvestigating the performance of model order reduction techniques for nonlinear radiative heat transfer problems
Hickey, D.; Masset, Luc ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the International Conference on Advanced Computational Methods in Engineering (2011)

The problem of nonlinear radiative heat transfer is one of great importance to the aerospace industry. However, analysing large-scale, nonlinear, multiphysical, dynamical structures, by using mathematical ... [more ▼]

The problem of nonlinear radiative heat transfer is one of great importance to the aerospace industry. However, analysing large-scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally expensive. This provides motivation for the development of Model-Order Reduction (MOR) techniques capable of reducing simulation times without the loss of important information. The objective is to demonstrate the method of Proper Orthogonal Decompostition (POD) as a technique for nonlinear MOR. The nonlinear radiative exchanges between a linear benchmark beam within an external box (Figure 1) are analysed and a reduction procedure for this fully coupled, nonlinear, multiphysical, thermomechanical system is established. The solution to the strongly coupled, thermomechanical equations of motion is found by making use of an extended version of the implicit generalized-alpha scheme. In the reduced model, the residual of the unreduced system of equations need to be evaluated at each Newton iteration of each time step. In order to optimise the efficiency of the reduction method it is shown that the internal forces can be split into their linear and nonlinear counterparts. Only the nonlinear terms change at each time step, thus only these terms need to remain in the iterative loop significantly reducing the number of parameters that are to be computed at each step. These efficiency improvements to the method are discussed and the results are given. [less ▲]

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See detailSimulation of machining processes at global scale using SAMCEF for machining
Masset, Luc ULg; Debongnie, Jean-François ULg

(2008, November)

SAMCEF for Machining is a professional solution dedicated to process engineers. This Computer Aided Engineering tool focuses on the simulation of the machined part behavior at a global scale. Several ... [more ▼]

SAMCEF for Machining is a professional solution dedicated to process engineers. This Computer Aided Engineering tool focuses on the simulation of the machined part behavior at a global scale. Several aspects of machining are taken into account such as form errors, chatter or thermal aspects. In this paper, we present a few industrial applications that demonstrate the benefits of simulation in production planning : reduction of setup delays, limitation of experimental validations, cost reduction. [less ▲]

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See detailUna proyección sintética para el diseño arquitectónico con la luz del sol
Benoit, Beckers; Masset, Luc ULg; Beckers, Pierre ULg

Conference (2007, October)

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See detailAn efficient simulation tool for predicting chatter during cutting operations
Le Lan, Jean-Vincent; Masset, Luc ULg; Marty, Audrey et al

Conference (2006, April)

The trends in chatter prediction are to compute stability lobes showing the maximal depth of cut versus spindle speed, following the work of Tlusty, Tobias and, more recently, Altintas. For mass ... [more ▼]

The trends in chatter prediction are to compute stability lobes showing the maximal depth of cut versus spindle speed, following the work of Tlusty, Tobias and, more recently, Altintas. For mass production such as the production of automotive parts, this kind of approach is not suitable because the goal is to find cutting conditions stable and independent of perturbations inherent to machining (clamping, rough part dimensions...). Still, in this method, the greatest allowable depth of cut to avoid chatter at any spindle speed is considered. The model is based on Tlusty's theory and the local stiffness of the machined surface is computed through a static finite element analysis. The result is a chatter map of the machined surface showing the maximal depth of cut at each node. [less ▲]

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See detailPrédiction numérique des défauts de forme engendrés par l'usinage
Debongnie, Jean-François ULg; Masset, Luc ULg

in Actes du 7ème Congrès de Mécanique. Volume I. Mécanique des Solides (2005, April)

Presentation of a prediction method of form errors arising during machining which has been developed in the manufacturing laboratory of the University of Liège. It combines empirical force models and a ... [more ▼]

Presentation of a prediction method of form errors arising during machining which has been developed in the manufacturing laboratory of the University of Liège. It combines empirical force models and a finite element model of the machined part. A particularly efficient solution scheme has been developed, leading to a valuable tool for the industry. [less ▲]

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See detailMachining process simulation using Samcef superelement
Masset, Luc ULg; Debongnie, Jean-François ULg; Marty, Audrey

Conference (2005, February)

In this paper, we present a new simulation tool for process engineers. During process design phases, several aspects of machining have to be taken into account. Classical CAD/CAM suites still lack some ... [more ▼]

In this paper, we present a new simulation tool for process engineers. During process design phases, several aspects of machining have to be taken into account. Classical CAD/CAM suites still lack some crucial issues. The goal of the developed tool is to predict the geometric errors of machined surfaces. For classical applications of the automotive domain, form errors are mainly due to the machined part and clamping system flexibility. They are modeled thanks to the FE method. The major peculiarity of the adopted model is to apply numerous load cases. To achieve a low computational coast, we have combined the SAMCEF superelement feature and a specific code to solve the reduced system. This original scheme allows solving efficiently large industrial applications. [less ▲]

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See detailMachining processes simulation : specific finite element aspects
Masset, Luc ULg; Debongnie, Jean-François ULg

in Journal of Computational & Applied Mathematics (2004, July 01), 168(1-2), 309-320

The paper presents a simulation tool designed to predict form errors of part surfaces obtained by face milling and turning processes. For these operations, the form error is often due to the flexibility ... [more ▼]

The paper presents a simulation tool designed to predict form errors of part surfaces obtained by face milling and turning processes. For these operations, the form error is often due to the flexibility of the workpiece and its supports. The finite element method is adopted to model the part geometry and to compute its deformations. Numerous load cases are required to obtain the form error so that classical resolution methods prove to be inefficient (CPU time, memory and disk space). The paper mainly focuses on the special computation scheme adopted in order to improve the resolution of such an atypical problem. [less ▲]

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See detailChatter maps for process design of powertrain components
Masset, Luc ULg; Debongnie, Jean-François ULg; Belluco, Walter

in Moisan, Alphonse; Poulachon, Gérard (Eds.) Proceedings of the 7th CIRP International Workshop on Modeling of Machining Operations (2004, May)

During rough machining operations of powertrain components, chatter vibrations may occur on the edges of flexible structures. This paper presents a numerical method, based on the finite element method and ... [more ▼]

During rough machining operations of powertrain components, chatter vibrations may occur on the edges of flexible structures. This paper presents a numerical method, based on the finite element method and Tlusty's theory, which gives a chatter map of the machined surface. Each map point represents the greatest depth of cut leading to unconditionally stable cut. Each value depends on the structural damping, the cutting stiffness and the local static stiffness, which is computed using conventional linear elastic FEA. Chatter maps offer a convenient and effective decision support system for robust process design. As a case study, the rough milling operation of a crankcase deck face with a two-stage cutter is presented. [less ▲]

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See detailSolving problems with contact in machining process simulation
Masset, Luc ULg; Debongnie, Jean-François ULg; Berger, Frederic

in Brucato, Valerio (Ed.) Proceedings of the 6th International ESAFORM Conference on Material Forming (2003, April)

At the 2001 Esaform conference, we have presented a simulation tool designed to predict form errors of part surfaces obtained by face milling and turning processes. The most relevant aspect of the ... [more ▼]

At the 2001 Esaform conference, we have presented a simulation tool designed to predict form errors of part surfaces obtained by face milling and turning processes. The most relevant aspect of the developed method is its ability to solve industrial cases with huge 3D finite element meshes in a very small time. Until recently, we were only considering pure linear problems. However, the simulation of several machining operations requires the introduction of contact. The present paper describes the numerical method developed to solve such non linear problems. [less ▲]

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See detailFonctionnement et performances des couloirs oscillants à glissement
Debongnie, Jean-François ULg; Masset, Luc ULg

in European Journal of Mechanical and Environmental Engineering (2001), 46(4), 243-254

This paper is devoted to the study of the efficiency of an oscillating trough for any value of the frequency. It is found that pure slipping or mixed cycles may occur, the latter comprising sticking ... [more ▼]

This paper is devoted to the study of the efficiency of an oscillating trough for any value of the frequency. It is found that pure slipping or mixed cycles may occur, the latter comprising sticking periods. The results of the present analysis concern the cyclic displacement, the mean velocity and the dissipated power. [less ▲]

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See detailFace milling and turning simulation with the finite element method
Masset, Luc ULg; Debongnie, Jean-François ULg; Beckers, Pierre ULg

in Habraken, Anne (Ed.) Proceedings of the 4th International ESAFORM Conference on Material Forming (2001, April)

The paper describes a new simulation tool that gives the machined surface error in face milling and turning. The form error component due to the workpiece flexibility is computed using Samcef finite ... [more ▼]

The paper describes a new simulation tool that gives the machined surface error in face milling and turning. The form error component due to the workpiece flexibility is computed using Samcef finite element code. The finite element analyses are very efficient on industrial applications thanks to the superelement method. Results are obtained in a short time which makes possible a wide range of simulations such as finding the best tool trajectory, testing several tools and cutting conditions and choosing the most suited fixture design. [less ▲]

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See detailControlling form errors from 3D measures
Debongnie, Jean-François ULg; Masset, Luc ULg

in ASME (Ed.) Proceedings of the 1999 ASME Design Engineering Technical Conference (1999, September)

Owing to the fact that a correct evaluation of form errors is particularly difficult by the classical ways, it seems more efficient to develop numerical algorithms from 3D measures. Several methods are ... [more ▼]

Owing to the fact that a correct evaluation of form errors is particularly difficult by the classical ways, it seems more efficient to develop numerical algorithms from 3D measures. Several methods are described, including direct and iterative ones. A new method is proposed, which is based on Lp-norms and a specialized algorithm. It proved to be the most effective and robust one on every studied application. [less ▲]

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