Papers by Sébastien Besset
International Journal for Numerical Methods in Engineering, 2008
This paper proposes modal criteria to represent various noise sources within a complex structure,... more This paper proposes modal criteria to represent various noise sources within a complex structure, such as an automobile. By optimizing a complex system using criteria linked to modal mass and stiffness matrices, different modes of noise propagation can be investigated separately. Several criteria are thus suggested, each related to a vibrational propagation path. Since the system is studied using modal analysis, criteria can be found based on modes associated with the structure's hollow parts, plates, and cavities. These different criteria are analyzed based on the assumption of a complex vibroacoustic system. It is shown that by analyzing such criteria, one can determine which part of the structure needs to be optimized. The optimization of such a system could constitute a research topic in its own right, and is beyond the scope of the present paper.
HAL (Le Centre pour la Communication Scientifique Directe), May 18, 2015
Le but de ce travail est de présenter une technique d'optimisation de structure multi-objectifs, ... more Le but de ce travail est de présenter une technique d'optimisation de structure multi-objectifs, basée sur l'utilisation d'algorithmes génétiques et de modèles éléments finis (MEF) mixtes. En effet, les algorithmes génétiques sont très largement utilisés pour des optimisations multi-objectifs, mais présentent l'inconvénient d'une grande répétition de calcul. Dans le cas d'une optimisation sous critères de contraintes, l'idée de ce travail est de construire un MEF mixte qui discrétise à la fois les déplacements et les contraintes, et permet d'accéder à ces dernières plus facilement. Mots clés -Optimisation multi-objectifs, éléments finis mixtes, critère de contrainte, modèle plaques, conception
InTech eBooks, Sep 9, 2011
This study will focus on the acoustic parts of the coupled system using acoustic modes and based ... more This study will focus on the acoustic parts of the coupled system using acoustic modes and based on a "triple modal synthesis method", which relies on a coupling formulation previously investigated by . An example of the modal analysis of a coupled system can be found in . A modal analysis of the structure will yield modal mass and stiffness matrices, which can then be used to obtain effective modal parameters and in turn lead to criteria that allow optimizing the structure. These criteria will depend on the pressure values at points located in the acoustic parts of the system, e.g. inside a car, as a function of an excitation point located on a hollow part of the structure, e.g. a spar near the car engine. The criteria proposed herein allow for various vibrational propagation paths to be considered. It is thus possible to separately investigate the various noise sources within the structure. The method proposed in this chapter may be used for any vibro-acoustic system. In fact, the ultimate goal of this approach is to define modal criteria that allow optimizing the vibro-acoustic system. Such criteria are related to the coupling terms between the systems' various substructures and are expressed as functions of the terms contained in the modal matrices. The number of criteria therefore depends on the number of substructures within the vibro-acoustic system. While our method will be described for the case of a specific system, keep in mind that it can be readily adapted to other vibro-acoustic systems. The structure considered in this chapter is complex and comprises acoustic cavities, hollow parts and plates. The geometry of this structure is similar to that of a car. Two cavities will be considered. Consequently, this proposed method can be used to study all of the different paths through which vibrations propagate and generate noise within the car. Paths can exist through the hollow parts of the structure, as well as through the plates bounding the cavity and through the plates partitioning the two cavities.
Structural and Multidisciplinary Optimization, Sep 25, 2015
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
International Journal for Numerical Methods in Engineering, Jan 14, 2010
This paper deals with modal criteria allowing optimization of structures through structural acous... more This paper deals with modal criteria allowing optimization of structures through structural acoustic control (ASAC) based on the independent modal strategy control (IMSC). The aim of the paper is to propose efficient criteria allowing to process optimization of structures by determining the most important modes to control considering only the location of the excitation on the structure. A generalized modal synthesis is used to study the coupled fluid-structure system. Modal criteria are proposed in order to determine the best choice for the controlled modes used in IMSC method. The way the ASAC will be applied is not discussed in the paper. Numerical simulations are computed to show the efficiency of the method, considering a simple vibroacoustic structure.
Applied Acoustics, Sep 1, 2011
Acoustic modelling, applicable to poroelastic materials in a wide frequency range, is time consum... more Acoustic modelling, applicable to poroelastic materials in a wide frequency range, is time consuming. This paper offers an energy method for optimising absorption coefficients at the boundaries of an acoustic cavity. The influence of absorption coefficients on this proposed energy method will be examined first. The next step will seek to optimise the location of absorbing materials. Numerical results will prove the method's effectiveness. Improvements in the overall optimisation process will also be proposed. A model based on polynomial interpolations will be developed in order to further reduce time consumption.
HAL (Le Centre pour la Communication Scientifique Directe), May 18, 2015
Dans la modélisation des joints de portes et de vitrages pour la prédiction du bruit aérodynamiqu... more Dans la modélisation des joints de portes et de vitrages pour la prédiction du bruit aérodynamique il est nécessaire de sortir du domaine classique du calcul vibro-acoustique linéaire, en raison du caractère fortement non-linéaire des joints. La déformation lors de la fermeture des portes ou vitres provoque des modifications des raideurs statique et dynamique, de l'amortissement et de la transparence acoustique des joints. Ensuite les efforts aérodynamiques modifient cette déformée statique lorsque le véhicule roule, ce qui amène aussi à des phénomènes d'interaction fluide-structure.
The purpose of this study is to implement a powerful multi-objective (MO) genetic algorithm(GA)-b... more The purpose of this study is to implement a powerful multi-objective (MO) genetic algorithm(GA)-based optimization technique for structural problems, based on the use of displacement-generalized stress Dynamic Mixed plate Finite Element Model (DMplate-FEM). The idea is to optimize different thickness parameters of a plate structure in order to minimize antagonist objectives among these stress criteria under dynamic loads. In this article, the optimization is performed with a GA-based iterative method and propose a set of Pareto-optimal solutions, leaving the final choice to the user. The repetitions of the calculations in this method is offset by the use of the displacement-stress mixed plate FEM. Such a model discretizes both displacements and generalized stresses in the same model, in order to get the latter directly and increase the efficiency of the method. The implementation of the Kirchoff-Love (KL) plate theory also improve the work of the GA as it allows a quick change of the thickness structure parameters without rebuilding the whole assembly. The number and complexity of calculations needed by the GA is thus smaller and the speed of the method highly improved. A few numerical investigations are made with both simple and complex test examples in order to validate the methods and show its relevance. This work shows efficient and promising results that may turn out to be interesting regarding industrial optimization cases with plate structures.
Archive of Applied Mechanics, Oct 19, 2015
This paper presents a methodology for the reduction of Dynamic Mixed Finite Element Models (DM-FE... more This paper presents a methodology for the reduction of Dynamic Mixed Finite Element Models (DM-FEMs) based on the use of a sub-structuring primal methods adapted to such models. We implement a DM-FEM for Kirchhoff-Love (KL) thin plates using the Hellinger-Reissner (HR) variational mixed formulation adapted to dynamic, and give a quick insight of its convergence. This model uses both displacement and generalized stress fields within the plate, obtained as a primary result, but the numerical size of the model is bigger than with a primal displacement model. Thus we choose to offset this complication by reducing the model with a totally new sub-structuring reduction method, especially adapted to DM-FEMs. The aim of our method is to adapt sub-structuring reduction methods commonly used for primal displacement FEM only (such as Craig & Bampton method) and split the reduction of the two fields. With these displacement methods, the whole structure is splitted into few smaller ones, and each of them is condensed with eigenmodes of the sub-structure and static connections between them. The principle of our method is to build, for each sub-structure, a reduced basis for the displacements according to the existing method, and a projection of the primal basis for the stresses. A new reduced basis for the whole mixed model is then built up exclusively with modes taken from the primal model. That method reduces significantly the number of degrees of freedom (DOF), and keeps the properties and advantages of the mixed formulation.
Archive of Applied Mechanics, Dec 19, 2012
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
European Journal of Mechanics A-solids, Sep 1, 2015
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
European Journal of Mechanics A-solids, 2009
Complex structures used in the automotive industry often include porous materials, in order to re... more Complex structures used in the automotive industry often include porous materials, in order to reduce the noise in acoustic cavities. The method proposed in this paper aims at optimizing the characteristics of these porous materials using modal criteria based on the modal analysis of the structure. The use of a generalize modal synthesis method allow to describe the structure and the cavities with sets of modes; the size of the resulting system is smaller, for only generalized degrees of freedom are used for each part of the coupled fluid-structure system. First, a modelization of the porous media is proposed, and the generalized modal analysis method is explained. An optimization is then processed on the thickness of the porous materials.
International audienceDans la modélisation des joints de portes et de vitrages pour la prédiction... more International audienceDans la modélisation des joints de portes et de vitrages pour la prédiction du bruit aérodynamique il est nécessaire de sortir du domaine classique du calcul vibro-acoustique linéaire, en raison du caractère fortement non-linéaire des joints. La déformation lors de la fermeture des portes ou vitres provoque des modifications des raideurs statique et dynamique, de l'amortissement et de la transparence acoustique des joints. Ensuite les efforts aérodynamiques modifient cette déformée statique lorsque le véhicule roule, ce qui amène aussi à des phénomènes d'interaction fluide-structure
International audienceLe crissement de frein reste une problématique d’actualité tant au niveau i... more International audienceLe crissement de frein reste une problématique d’actualité tant au niveau industriel qu’académique. L’analyse transitoire non linéaire est une approche prometteuse, elle est cependant gourmande en ressources informatiques. La double synthèse modale est une méthode de réduction qui rend possible la réalisation d’intégrations temporelles non linéaires sur la base de modèles éléments finis industriels réalistes. Il est illustré ici la réduction de multiples interfaces frottantes de grandes dimensions sur une base réduite, permettant de réaliser des simulations jusqu e-là inaccessibles
HAL (Le Centre pour la Communication Scientifique Directe), May 13, 2013
Afin de réaliser des simulations transitoires dynamiques non-linéaires d'un système de frein mult... more Afin de réaliser des simulations transitoires dynamiques non-linéaires d'un système de frein multi-disques, une réduction par sous-structuration est effectuée. Deux méthodes de réduction de l'ensemble des disques sont mises en place. Elles permettent de prendre en compte le frottement présent à l'interface des disques et leur comportement non-linéaire.
Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2015
The purpose of this study is to implement a powerful multi-objective (MO) genetic algorithm(GA)-b... more The purpose of this study is to implement a powerful multi-objective (MO) genetic algorithm(GA)-based optimization technique for structural problems, based on the use of displacement-generalized stress Dynamic Mixed plate Finite Element Model (DMplate-FEM). The idea is to optimize different thickness parameters of a plate structure in order to minimize antagonist objectives among these stress criteria under dynamic loads. In this article, the optimization is performed with a GA-based iterative method and propose a set of Pareto-optimal solutions, leaving the final choice to the user. The repetitions of the calculations in this method is offset by the use of the displacement-stress mixed plate FEM. Such a model discretizes both displacements and generalized stresses in the same model, in order to get the latter directly and increase the efficiency of the method. The implementation of the Kirchoff-Love (KL) plate theory also improve the work of the GA as it allows a quick change of the thickness structure parameters without rebuilding the whole assembly. The number and complexity of calculations needed by the GA is thus smaller and the speed of the method highly improved. A few numerical investigations are made with both simple and complex test examples in order to validate the methods and show its relevance. This work shows efficient and promising results that may turn out to be interesting regarding industrial optimization cases with plate structures.
Le but de ce travail est de presenter une technique d’optimisation de structure multi-objectifs, ... more Le but de ce travail est de presenter une technique d’optimisation de structure multi-objectifs, basee sur l’utilisation d’algorithmes genetiques et de modeles elements finis (MEF) mixtes. En effet, les algorithmes genetiques sont tres largement utilises pour des optimisations multi-objectifs, mais presentent l’inconvenient d’une grande repetition de calcul. Dans le cas d’une optimisation sous criteres de contraintes, l’idee de ce travail est de construire un MEF mixte qui discretise a la fois les deplacements et les contraintes, et permet d’acceder a ces dernieres plus facilement.
Archive of Applied Mechanics, 2015
This paper presents a methodology for the reduction of Dynamic Mixed Finite Element Models (DM-FE... more This paper presents a methodology for the reduction of Dynamic Mixed Finite Element Models (DM-FEMs) based on the use of a sub-structuring primal methods adapted to such models. We implement a DM-FEM for Kirchhoff-Love (KL) thin plates using the Hellinger-Reissner (HR) variational mixed formulation adapted to dynamic, and give a quick insight of its convergence. This model uses both displacement and generalized stress fields within the plate, obtained as a primary result, but the numerical size of the model is bigger than with a primal displacement model. Thus we choose to offset this complication by reducing the model with a totally new sub-structuring reduction method, especially adapted to DM-FEMs. The aim of our method is to adapt sub-structuring reduction methods commonly used for primal displacement FEM only (such as Craig & Bampton method) and split the reduction of the two fields. With these displacement methods, the whole structure is splitted into few smaller ones, and each of them is condensed with eigenmodes of the sub-structure and static connections between them. The principle of our method is to build, for each sub-structure, a reduced basis for the displacements according to the existing method, and a projection of the primal basis for the stresses. A new reduced basis for the whole mixed model is then built up exclusively with modes taken from the primal model. That method reduces significantly the number of degrees of freedom (DOF), and keeps the properties and advantages of the mixed formulation.
Mécanique & Industries, 2008
La qualité sonore des véhicules constitue aujourd'hui un critère important de conception. Dans ce... more La qualité sonore des véhicules constitue aujourd'hui un critère important de conception. Dans ce cadre, la détection de sources acoustiques est une problématique majeure. En effet, si l'analyse du bruit dans une cavité peut être traitée de manière classique (FEM, BEM...), les problèmes inverses posent souvent des problèmes liés à la taille des calculs effectués ou au conditionnement des matrices à inverser. Nous nous proposons ici d'étudier une méthode énergétique simplifiée (MES) qui présente la particularité d'être avantageusement inversible. Le but de la méthode proposée est de parvenir à localiser des sources acoustiques surfaciques à partir de mesures effectuées dans une cavité. Source acoustique / bruit / problème inverse / méthode énergétique simplifiée (MES) / hautes fréquences Abstract -Inverse energy method applied to the acoustic sources detection. The sound quality of the vehicles constitutes today a significant criterion of design. Within this framework, the detection of acoustic sources is a major problem. In fact, if the noise analysis in a cavity can be treated in a traditional way (FEM, BEM...), inverse methods often generate problems related to calculation size carried out or the conditioning of the matrices to be inversed. We propose to study a simplified energy method (SEM) which has the effect of being advantageously inversed. The suggested method objective is to locate surface acoustic sources starting from measurements taken in a cavity.
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Papers by Sébastien Besset