Khaled Souaissa, J. Cuillière, V. François, A. Benamara, H. Belhadjsalah
Several research works have been focused on integrating FEA (finite-elements analysis) with CAD (Computer Aided Design) over the last decade. In spite of the improvements brought by this inte- gration, research work remains to be done in order to better integrate all the operations led during the design process. Until now, the communication between CAD modules remains static. The design process involves several modifications of an initial design solution. Consequently, there is a need for more flexible communications between CAD modules through the design cycle. Some approaches have been developed in order to reduce the design process length when using FEA, and to automate the transfer of part's data from one step of the process to the next one. Automatic re-meshing is one of these approaches and it is based on automatically updating the part's mesh around modifications zones, in the case of a minor change in the part's design, without the need to re-mesh the entire part. The purpose of this paper is presenting a new tool, aiming at the improvement of automatic re-meshing procedures. It basically consists in auto- matically identifying and locating modifications between two CAD parts (typically an initial design and a modified design). A major benefit of the approach presented here is that it is completely independent of the description frame, which is made possible with the use of vector-based geometric representations.
{"title":"Automatic modification retrieval between CAD parts","authors":"Khaled Souaissa, J. Cuillière, V. François, A. Benamara, H. Belhadjsalah","doi":"10.1051/MECA/2010020","DOIUrl":"https://doi.org/10.1051/MECA/2010020","url":null,"abstract":"Several research works have been focused on integrating FEA (finite-elements analysis) with CAD (Computer Aided Design) over the last decade. In spite of the improvements brought by this inte- gration, research work remains to be done in order to better integrate all the operations led during the design process. Until now, the communication between CAD modules remains static. The design process involves several modifications of an initial design solution. Consequently, there is a need for more flexible communications between CAD modules through the design cycle. Some approaches have been developed in order to reduce the design process length when using FEA, and to automate the transfer of part's data from one step of the process to the next one. Automatic re-meshing is one of these approaches and it is based on automatically updating the part's mesh around modifications zones, in the case of a minor change in the part's design, without the need to re-mesh the entire part. The purpose of this paper is presenting a new tool, aiming at the improvement of automatic re-meshing procedures. It basically consists in auto- matically identifying and locating modifications between two CAD parts (typically an initial design and a modified design). A major benefit of the approach presented here is that it is completely independent of the description frame, which is made possible with the use of vector-based geometric representations.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"12 1","pages":"85-92"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87435167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper discusses the characteristics of time-frequency estimators to be used in the identification of systems with localized non-linearities. The common idea underlying this research is that, for certain classes of structural response signals, the availability of a limited number of experimental data can be partially obviated by taking into account the “localisation” in time of the frequency components of the signals. Time-frequency techniques for structural identification are reported that extend the definition of instantaneous time-frequency estimators and Gabor instantaneous estimators were extracted from non-stationary vibration signals. In order to foresee their validity on the basis of measured data, methods were applied to seismic responses obtained from numerical tests conducted on steel frames. The results obtained made it possible to evaluate the characteristics of time-frequency identification techniques as well as their efficiency when applied to non-linear structures.
{"title":"Instantaneous identification of localized non-linearities in steel framed structures","authors":"P. Argoul, R. Ceravolo, G. Demarie, D. Sabia","doi":"10.1051/MECA/2010022","DOIUrl":"https://doi.org/10.1051/MECA/2010022","url":null,"abstract":"This paper discusses the characteristics of time-frequency estimators to be used in the\u0000 identification of systems with localized non-linearities. The common idea underlying this\u0000 research is that, for certain classes of structural response signals, the availability of\u0000 a limited number of experimental data can be partially obviated by taking into account the\u0000 “localisation” in time of the frequency components of the signals. Time-frequency\u0000 techniques for structural identification are reported that extend the definition of\u0000 instantaneous time-frequency estimators and Gabor instantaneous estimators were extracted\u0000 from non-stationary vibration signals. In order to foresee their validity on the basis of\u0000 measured data, methods were applied to seismic responses obtained from numerical tests\u0000 conducted on steel frames. The results obtained made it possible to evaluate the\u0000 characteristics of time-frequency identification techniques as well as their efficiency\u0000 when applied to non-linear structures.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"19 1","pages":"105-116"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85218174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ce travail presente l’etude du comportement dynamique d’un systeme soumis a des instabilites de type Sprag-Slip generees par du frottement. La mise en equation de ce systeme conduit a un systeme d’equations differentielles non lineaire. Dans un premier temps, une approche deterministe du comportement est realisee : la resolution classique de ces equations differentielles permet de determiner le comportement dynamique du systeme etudie, ainsi que sa sensibilite aux differents parametres. Dans un second temps, une analyse par intervalle permet de prendre en compte la dispersion du coefficient de frottement pour l’integration des equations differentielles. L’objectif est d’obtenir une modelisation robuste du comportement dynamique de systemes frottants.
{"title":"Modelisation robuste du comportement dynamique d'un systeme non-lineaire frottant","authors":"Pascal Ragot, S. Berger, Evelyne Aubry","doi":"10.1051/MECA/2010024","DOIUrl":"https://doi.org/10.1051/MECA/2010024","url":null,"abstract":"Ce travail presente l’etude du comportement dynamique d’un systeme soumis a des instabilites de type Sprag-Slip generees par du frottement. La mise en equation de ce systeme conduit a un systeme d’equations differentielles non lineaire. Dans un premier temps, une approche deterministe du comportement est realisee : la resolution classique de ces equations differentielles permet de determiner le comportement dynamique du systeme etudie, ainsi que sa sensibilite aux differents parametres. Dans un second temps, une analyse par intervalle permet de prendre en compte la dispersion du coefficient de frottement pour l’integration des equations differentielles. L’objectif est d’obtenir une modelisation robuste du comportement dynamique de systemes frottants.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"30 1","pages":"123-132"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81021939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Un modele numerique permettant d’etudier l’influence du comportement elastique non-lineaire des conduites dans les ecoulements transitoires avec cavitation de vapeur est presente. L’application des lois de conservation de la masse et de la quantite de mouvement aboutit a un systeme de deux equations aux derivees partielles de type hyperbolique qui se resout numeriquement par un schema predicteur-correcteur aux differences finies conservatif. Par analogie avec la loi de Henry pour le degazage de l’air dissous, une quantite de vapeur se degage des que la pression devient inferieure a la pression de vapeur du liquide. Pour mettre en evidence l’interaction fluide-structure, une relation liant la pression a la section de la conduite a ete introduite. Les resultats obtenus permettent d’etudier l’influence de la deformation de la paroi de la conduite sur l’evolution des phenomenes de coup de belier et de cavitation de vapeur. La formulation mathematique presentee est validee en comparant ces resultats a ceux experimentaux tires de la litterature.
{"title":"Influence du comportement élastique non-linéaire des conduites dans les écoulements transitoires avec cavitation de vapeur","authors":"Lamjed Hadj-Ta¨ıeb, Ezzeddine Hadj-ta¨ıeb","doi":"10.1051/MECA/2010026","DOIUrl":"https://doi.org/10.1051/MECA/2010026","url":null,"abstract":"Un modele numerique permettant d’etudier l’influence du comportement elastique non-lineaire des conduites dans les ecoulements transitoires avec cavitation de vapeur est presente. L’application des lois de conservation de la masse et de la quantite de mouvement aboutit a un systeme de deux equations aux derivees partielles de type hyperbolique qui se resout numeriquement par un schema predicteur-correcteur aux differences finies conservatif. Par analogie avec la loi de Henry pour le degazage de l’air dissous, une quantite de vapeur se degage des que la pression devient inferieure a la pression de vapeur du liquide. Pour mettre en evidence l’interaction fluide-structure, une relation liant la pression a la section de la conduite a ete introduite. Les resultats obtenus permettent d’etudier l’influence de la deformation de la paroi de la conduite sur l’evolution des phenomenes de coup de belier et de cavitation de vapeur. La formulation mathematique presentee est validee en comparant ces resultats a ceux experimentaux tires de la litterature.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"7 1","pages":"149-156"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80395312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
La transition vers la turbulence en conduite cylindrique est observee pour Re assez grand, malgre la stabilite lineaire de l’etat laminaire. Experimentalement, la transition se manifeste par le developpement de bouffees turbulentes, spatialement localisees. Du cote theorique, des ondes progressives, instables et de courte longueur d’onde, ont ete mises en evidence numeriquement. Cette etude, qui utilise la simulation numerique directe ainsi qu’un modele reduit, suggere la compatibilite entre les deux approches.
{"title":"États limites et bouffées turbulentes en conduite cylindrique","authors":"Yoann Duguet, Ashley P. Willis, Rich R. Kerswell","doi":"10.1051/MECA/2010027","DOIUrl":"https://doi.org/10.1051/MECA/2010027","url":null,"abstract":"La transition vers la turbulence en conduite cylindrique est observee pour\u0000 Re assez grand, malgre la stabilite lineaire de l’etat laminaire.\u0000 Experimentalement, la transition se manifeste par le developpement de bouffees\u0000 turbulentes, spatialement localisees. Du cote theorique, des ondes progressives, instables\u0000 et de courte longueur d’onde, ont ete mises en evidence numeriquement. Cette etude, qui\u0000 utilise la simulation numerique directe ainsi qu’un modele reduit, suggere la\u0000 compatibilite entre les deux approches.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"35 1","pages":"157-162"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86563891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Francisco Mata Cabrera, I. Hanafi, Abdellatif Khamlichi, A. Jabbouri, Mohamed Bezzazi
Une revue bibliographique etendue est realisee sur le theme de l’usinabilite des composites a matrice polymere renforcee par des fibres, dans le but de fournir des resultats et conclusions sur l’usinage des materiaux composites a matrice thermoplastique et a fibres courtes. Un rappel sur l’etat de l’art dans ce domaine, sur les specificites liees a l’usinage des composites organiques et sur les differents modeles ayant ete introduits pour predire les parametres de coupe a ete effectue. Les parametres affectant l’usinabilite proprement dite des composites ont ete revus, ensuite une riche bibliographie sur le sujet est presentee. Enfin les criteres d’usinage ont ete presentes sous forme synthetique en considerant les differentes contributions developpees dans ce domaine et, de maniere presque exhaustive, toutes les references bibliographiques significatives ayant traite de ce sujet.
{"title":"Sur l’usinabilité des composites à matrices polymères renforcée par des fibres","authors":"Francisco Mata Cabrera, I. Hanafi, Abdellatif Khamlichi, A. Jabbouri, Mohamed Bezzazi","doi":"10.1051/MECA/2010021","DOIUrl":"https://doi.org/10.1051/MECA/2010021","url":null,"abstract":"Une revue bibliographique etendue est realisee sur le theme de l’usinabilite des composites a matrice polymere renforcee par des fibres, dans le but de fournir des resultats et conclusions sur l’usinage des materiaux composites a matrice thermoplastique et a fibres courtes. Un rappel sur l’etat de l’art dans ce domaine, sur les specificites liees a l’usinage des composites organiques et sur les differents modeles ayant ete introduits pour predire les parametres de coupe a ete effectue. Les parametres affectant l’usinabilite proprement dite des composites ont ete revus, ensuite une riche bibliographie sur le sujet est presentee. Enfin les criteres d’usinage ont ete presentes sous forme synthetique en considerant les differentes contributions developpees dans ce domaine et, de maniere presque exhaustive, toutes les references bibliographiques significatives ayant traite de ce sujet.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"6 1","pages":"93-103"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75401387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The long-period components in earthquake ground motions, which attenuate gradually with distance, can induce sloshing waves in the liquid containment tanks although they are located far away from the seismic source. The resulting sloshing waves generate additional forces impacting the wall and roof of the tanks and may cause extensive damage on the tank structure. Numerous examples of tank damages due to sloshing of fluid have been observed during many earthquakes. Nevertheless, the effect of sloshing is usually primitively considered in most of the seismic design codes of tanks. On the other hand, the derivation of an analytical solution for the sloshing response of a liquid storage tank subjected to harmonic excitation includes many assumptions and simplifications. Most of the analytical solutions in the recent literature assumed the containing liquid to be invicid, incompressible and irrotational, and the tank structure to be an isotropic elastic plate with uniform stiffness, mass and thickness. Even though, experimental works are necessary to study the actual behavior of the system, they are time consuming, very costly and performed only for specific boundary and excitation conditions. However, appropriate numerical simulation using fluid structure interaction techniques can be used to predict the hydrodynamic forces due to the high-speed impacts of sloshing liquid on a tank wall and roof. These simulations can reduce the number of experimental tests. The nonlinear finite element techniques with either Lagrangian and/or Eulerian formulations may be employed as a numerical method to model sloshing problems. But, most of the Lagrangian formulations used to solve such problems have failed due to high mesh distortion of the fluid. The arbitrary Lagrangian Eulerian techniques are capable of keeping mesh integrity during the motion of the tank. In this study, an explicit nonlinear finite element analysis method with ALE algorithm is developed and sloshing phenomenon is analyzed. The analysis capabilities of the method are explained on a technical level. Although, the developed numerical procedure is applicable to deformable structures, the accuracy of the method is validated with the existing analytical formulation derived from potential flow theory as well as the experimental data carried out on rigid tanks when subjected to harmonic and earthquake ground motions. High consistency between numerical and experimental results in terms of peak level timing, shape and amplitude of sloshing waves is obtained not only for non-resonant excitation but also for resonant frequency motion.
{"title":"FSI methods for seismic analysis of sloshing tank problems","authors":"Z. Ozdemir, M. Souli, Y. Fahjan","doi":"10.1051/MECA/2010025","DOIUrl":"https://doi.org/10.1051/MECA/2010025","url":null,"abstract":"The long-period components in earthquake ground motions, which attenuate gradually with distance, can induce sloshing waves in the liquid containment tanks although they are located far away from the seismic source. The resulting sloshing waves generate additional forces impacting the wall and roof of the tanks and may cause extensive damage on the tank structure. Numerous examples of tank damages due to sloshing of fluid have been observed during many earthquakes. Nevertheless, the effect of sloshing is usually primitively considered in most of the seismic design codes of tanks. On the other hand, the derivation of an analytical solution for the sloshing response of a liquid storage tank subjected to harmonic excitation includes many assumptions and simplifications. Most of the analytical solutions in the recent literature assumed the containing liquid to be invicid, incompressible and irrotational, and the tank structure to be an isotropic elastic plate with uniform stiffness, mass and thickness. Even though, experimental works are necessary to study the actual behavior of the system, they are time consuming, very costly and performed only for specific boundary and excitation conditions. However, appropriate numerical simulation using fluid structure interaction techniques can be used to predict the hydrodynamic forces due to the high-speed impacts of sloshing liquid on a tank wall and roof. These simulations can reduce the number of experimental tests. The nonlinear finite element techniques with either Lagrangian and/or Eulerian formulations may be employed as a numerical method to model sloshing problems. But, most of the Lagrangian formulations used to solve such problems have failed due to high mesh distortion of the fluid. The arbitrary Lagrangian Eulerian techniques are capable of keeping mesh integrity during the motion of the tank. In this study, an explicit nonlinear finite element analysis method with ALE algorithm is developed and sloshing phenomenon is analyzed. The analysis capabilities of the method are explained on a technical level. Although, the developed numerical procedure is applicable to deformable structures, the accuracy of the method is validated with the existing analytical formulation derived from potential flow theory as well as the experimental data carried out on rigid tanks when subjected to harmonic and earthquake ground motions. High consistency between numerical and experimental results in terms of peak level timing, shape and amplitude of sloshing waves is obtained not only for non-resonant excitation but also for resonant frequency motion.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"33 1","pages":"133-147"},"PeriodicalIF":0.0,"publicationDate":"2010-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86606520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
La modelisation et la simulation numerique permettent une exploration des differents parametres de controles afin d’identifier les conditions et geometries optimales de fonctionnement des systemes. Cette approche permet entre autre d’obtenir les valeurs instantanees des grandeurs physiques locales. Ces outils numeriques progressent et traitent des systemes de plus en plus complexes confortes par la progression des puissances des ordinateurs. Nous decrirons dans le present travail le cas de moteurs alternatifs de type Stirling, a combustion externe et regeneration. Ces moteurs constituent une solution pour la conversion efficace des energies renouvelables et des chaleurs perdues en travail. La simulation de tels systemes en regime etabli permettra d’en deduire les energies echangees et de demontrer que ces moteurs offrent un bon rendement de fonctionnement, tout en presentant une grande souplesse d’adaptation. L’optimisation des machines est fortement liee a leurs parametres geometriques et physiques (dimensions, materiaux, coefficient de transfert de chaleur, etc.) ce qui peut engendrer un cout important pour les differents prototypes. La simulation numerique permettra la prediction du cycle au cours du temps et donnera acces aux valeurs du travail ainsi que le rendement de la machine simulee. Cette demarche identifiera les zones de fonctionnements optimaux et reduira le nombre de prototypes et du meme coup le cout du projet. La modelisation s’appuie sur la resolution des equations de conservation d’ecoulements compressibles anisothermes dans un moteur LTD en domaine bidimensionnel (2D, moteur suppose axisymetrique afin de faciliter l’illustration). En guise de validation l’un des resultats obtenus numeriquement est confronte aux resultats experimentaux obtenus sur un prototype moteur de demonstration. Le bon accord constate sur le cycle p -V illustre l’interet methodologique.
{"title":"Simulation dynamique d’un moteur : cas du Stirling de type gamma","authors":"N. Martaj, R. Bennacer, P. Rochelle, L. Grosu","doi":"10.1051/MECA/2010017","DOIUrl":"https://doi.org/10.1051/MECA/2010017","url":null,"abstract":"La modelisation et la simulation numerique permettent une exploration des differents parametres de controles afin d’identifier les conditions et geometries optimales de fonctionnement des systemes. Cette approche permet entre autre d’obtenir les valeurs instantanees des grandeurs physiques locales. Ces outils numeriques progressent et traitent des systemes de plus en plus complexes confortes par la progression des puissances des ordinateurs. Nous decrirons dans le present travail le cas de moteurs alternatifs de type Stirling, a combustion externe et regeneration. Ces moteurs constituent une solution pour la conversion efficace des energies renouvelables et des chaleurs perdues en travail. La simulation de tels systemes en regime etabli permettra d’en deduire les energies echangees et de demontrer que ces moteurs offrent un bon rendement de fonctionnement, tout en presentant une grande souplesse d’adaptation. L’optimisation des machines est fortement liee a leurs parametres geometriques et physiques (dimensions, materiaux, coefficient de transfert de chaleur, etc.) ce qui peut engendrer un cout important pour les differents prototypes. La simulation numerique permettra la prediction du cycle au cours du temps et donnera acces aux valeurs du travail ainsi que le rendement de la machine simulee. Cette demarche identifiera les zones de fonctionnements optimaux et reduira le nombre de prototypes et du meme coup le cout du projet. La modelisation s’appuie sur la resolution des equations de conservation d’ecoulements compressibles anisothermes dans un moteur LTD en domaine bidimensionnel (2D, moteur suppose axisymetrique afin de faciliter l’illustration). En guise de validation l’un des resultats obtenus numeriquement est confronte aux resultats experimentaux obtenus sur un prototype moteur de demonstration. Le bon accord constate sur le cycle p -V illustre l’interet methodologique.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"37 1","pages":"69-74"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73544664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The behaviour of dynamical systems is modified by the use of viscoelastic materials. In order to lead realistic complex eigenvalues analysis on dynamical systems, one need to model the behaviour of viscoelastic materials. The experiments show that the stiffness and the damping of such materials are frequency dependent. A large number of models often used are not able to describe this dependence; this is why the generalised Maxwell's model has been chosen. This paper describes a method based on modulus and angle curves to identify the parameters of this model. Between all the different formulations of generalized Maxwell, the pole-zero formulation is the most suited to lead the identification. However, some formulas allow to find the parameters of others formulations like the Prony one. The identification method presented here is based on the asymptotic curves of generalised Maxwell's model. This identification is led in two step, first parameters are initialised and second they are optimised. This method is confronted to others ones. If several viscoelastic materials have to be modelled in the same dynamical system, the size of the finite element model grows as quick as the number of poles. A way to reduce this size consists in constraining the poles to be equal for all materials. The method presented in this paper allows to perform the identification by taking this new constraint into account.
{"title":"Méthode d'identification des paramètres d'un modèle de Maxwell généralisé pour la modélisation de l'amortissement","authors":"F. Renaud, J. Dion, G. Chevallier","doi":"10.1051/MECA/2010015","DOIUrl":"https://doi.org/10.1051/MECA/2010015","url":null,"abstract":"The behaviour of dynamical systems is modified by the use of viscoelastic materials. In order to lead realistic complex eigenvalues analysis on dynamical systems, one need to model the behaviour of viscoelastic materials. The experiments show that the stiffness and the damping of such materials are frequency dependent. A large number of models often used are not able to describe this dependence; this is why the generalised Maxwell's model has been chosen. This paper describes a method based on modulus and angle curves to identify the parameters of this model. Between all the different formulations of generalized Maxwell, the pole-zero formulation is the most suited to lead the identification. However, some formulas allow to find the parameters of others formulations like the Prony one. The identification method presented here is based on the asymptotic curves of generalised Maxwell's model. This identification is led in two step, first parameters are initialised and second they are optimised. This method is confronted to others ones. If several viscoelastic materials have to be modelled in the same dynamical system, the size of the finite element model grows as quick as the number of poles. A way to reduce this size consists in constraining the poles to be equal for all materials. The method presented in this paper allows to perform the identification by taking this new constraint into account.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"3 1","pages":"47-55"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81077535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
La cyclostationnarite, propriete propre aux processus dont les caracteristiques evoluent cycliquement au cours du temps, offre un cadre particulierement adapte a l’analyse de nombreux signaux acoustiques et vibratoires. Apres avoir rappele les specificites de l’approche cyclostationnaire dans le contexte mecanique, nous montrons a travers plusieurs exemples les possibilites qu’elle autorise dans des domaines d’application lies au diagnostic des machines, a l’identification des systemes mecaniques et a la separation de sources vibro-acoustiques.
{"title":"Apports de la cyclostationnarité à l’analyse des signaux mécaniques","authors":"J. Antoni","doi":"10.1051/MECA/2010016","DOIUrl":"https://doi.org/10.1051/MECA/2010016","url":null,"abstract":"La cyclostationnarite, propriete propre aux processus dont les caracteristiques evoluent cycliquement au cours du temps, offre un cadre particulierement adapte a l’analyse de nombreux signaux acoustiques et vibratoires. Apres avoir rappele les specificites de l’approche cyclostationnaire dans le contexte mecanique, nous montrons a travers plusieurs exemples les possibilites qu’elle autorise dans des domaines d’application lies au diagnostic des machines, a l’identification des systemes mecaniques et a la separation de sources vibro-acoustiques.","PeriodicalId":49847,"journal":{"name":"Mecanique & Industries","volume":"58 1","pages":"57-68"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80171011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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