Touzé, Cyril
Overview
| Works: | 24 works in 28 publications in 2 languages and 34 library holdings |
|---|---|
| Genres: | Academic theses |
| Roles: | Opponent, Thesis advisor, Other, Author |
| Classifications: | ML3805, 784.1923 |
Publication Timeline
.
Most widely held works by
Cyril Touzé
Analyse et modélisation de signaux vibratoires et acoustiques chaotiques : application aux instruments de percussion non-linéaires by
Cyril Touzé(
Book
)
2 editions published in 2000 in French and held by 4 WorldCat member libraries worldwide
2 editions published in 2000 in French and held by 4 WorldCat member libraries worldwide
Nonlinear forced vibrations of thin structures with tuned eigenfrequencies: the cases of 1:2:4 and 1:2:2 internal resonances by
Mélodie Monteil(
)
1 edition published in 2013 in English and held by 2 WorldCat member libraries worldwide
1 edition published in 2013 in English and held by 2 WorldCat member libraries worldwide
Nonlinear Vibrations of Thin Rectangular Plates : A Numerical Investigation with Application to Wave Turbulence and Sound
Synthesis by
Michele Ducceschi(
Book
)
2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide
Thin plate vibrations display a rich and complex dynamics that ranges from linear to strongly nonlinear regimes when increasing the vibration amplitude with respect to the thickness. This thesis is concerned with the development of a numerical code able to simulate without restrictions this large spectrum of dynamical features, described by the von Kármán equations, in the case of flat, homogeneous plates presenting a rectangular geometry. The main application of such a code is to produce gong-like sounds, in the context of sound synthesis by physical modelling. For that, a modal approach is used, in order to reduce the original Partial Differential Equations to a set of couped Ordinary Differential Equations. An energy-conserving, second-order accurate time integration scheme is developed in order to yield a stability condition. The most appealing features of the modal scheme are its accuracy and the possibility of implementing a rich loss mechanism by selecting an appropriate damping factor for each one of the modes. The sound produced by the numerical code is systematically compared to another numerical technique based on Finite Difference techniques. Fundamental aspects of the physics of nonlinear vibrations are also considered in the course of this work. When a plate vibrates in a weakly nonlinear regime, modal couplings produce amplitude-dependent vibrations, internal resonances, instabilities, jumps and bifurcations. The modal scheme is used to construct and analyse the nonlinear response of the plate in the vicinity of its first eigenfrequencies, both in free and forced-damped vibrations, showing as a result the effect of damping and forcing on the nonlinear normal modes of the underlying Hamiltonian system. When plates vibrate in a strongly nonlinear regime, the most appropriate description of the dynamics is given in terms of the statistical properties of the system, because of the vast number of interacting degrees-of-freedom. Theoretically, this framework is offered by the Wave Turbulence theory. Given the large amount of modes activated in such vibrations, a Finite Difference, energy-conserving code is preferred over the modal scheme. Such a scheme allows to produce a cascade of energy including thousands of modes when the plate is forced sinusoidally around one of its lowest eigenfrequencies. A statistical interpretation of the outcome of the simulation is offered, along with a comparison with experimental data and other numerical results found in the literature. In particular, the effect of the pointwise forcing as well as geometrical imperfections of the plates are analysed
2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide
Thin plate vibrations display a rich and complex dynamics that ranges from linear to strongly nonlinear regimes when increasing the vibration amplitude with respect to the thickness. This thesis is concerned with the development of a numerical code able to simulate without restrictions this large spectrum of dynamical features, described by the von Kármán equations, in the case of flat, homogeneous plates presenting a rectangular geometry. The main application of such a code is to produce gong-like sounds, in the context of sound synthesis by physical modelling. For that, a modal approach is used, in order to reduce the original Partial Differential Equations to a set of couped Ordinary Differential Equations. An energy-conserving, second-order accurate time integration scheme is developed in order to yield a stability condition. The most appealing features of the modal scheme are its accuracy and the possibility of implementing a rich loss mechanism by selecting an appropriate damping factor for each one of the modes. The sound produced by the numerical code is systematically compared to another numerical technique based on Finite Difference techniques. Fundamental aspects of the physics of nonlinear vibrations are also considered in the course of this work. When a plate vibrates in a weakly nonlinear regime, modal couplings produce amplitude-dependent vibrations, internal resonances, instabilities, jumps and bifurcations. The modal scheme is used to construct and analyse the nonlinear response of the plate in the vicinity of its first eigenfrequencies, both in free and forced-damped vibrations, showing as a result the effect of damping and forcing on the nonlinear normal modes of the underlying Hamiltonian system. When plates vibrate in a strongly nonlinear regime, the most appropriate description of the dynamics is given in terms of the statistical properties of the system, because of the vast number of interacting degrees-of-freedom. Theoretically, this framework is offered by the Wave Turbulence theory. Given the large amount of modes activated in such vibrations, a Finite Difference, energy-conserving code is preferred over the modal scheme. Such a scheme allows to produce a cascade of energy including thousands of modes when the plate is forced sinusoidally around one of its lowest eigenfrequencies. A statistical interpretation of the outcome of the simulation is offered, along with a comparison with experimental data and other numerical results found in the literature. In particular, the effect of the pointwise forcing as well as geometrical imperfections of the plates are analysed
Comportement vibratoire du steelpan : effet des procédés de fabrication et dynamique non linéaire by
Mélodie Monteil(
Book
)
2 editions published in 2013 in French and held by 2 WorldCat member libraries worldwide
This study is devoted to the steelpan, a harmonically tuned percussion from Trinidad and Tobago. It consists in a steel barrel subjected to several steps of irreversible metal forming to obtain a main spherical bowl within wich convex domes are formed. This work is mainly focused on two topics. Firstly, the study of the making processes allows us to gain a better understanding of the work of the tuner in order to propose a model of the first step of steelpan making. Secondly, a vibration analysis of the steelpan, at the end of this process, is performed to understand its dynamics which is responsible of its particular tone. In the first part of the manuscript we study the evolution of the dynamical parameters during manufacturing. In particular, mode localization after note forming, strong variations of modal dampings, natural frequencies after burning and harmonic relationships after fine tuning are observed. The second part of the manuscript focusses on the first step of manufacturing during which the top of the barrel is hammered to obtain the spherical shell. The shell is analytically modeled as a nonlinear von Karman plate and the plastic strains are introduced as initial inelastic strains. The effect of the geometry and of the residual stress fields are separately quantified on the dynamical parameters of the structure in its final equilibrium state. The last part is concerned with the complex nonlinear dynamics of the steelpan at the end of the forming process. During normal playing, energy exchanges between modes are clearly identifiable: they result in a rich sound due to numerous internal resonances. Modal coupling are measured even for small amplitudes of vibrations. Original models of internal resonances are proposed
2 editions published in 2013 in French and held by 2 WorldCat member libraries worldwide
This study is devoted to the steelpan, a harmonically tuned percussion from Trinidad and Tobago. It consists in a steel barrel subjected to several steps of irreversible metal forming to obtain a main spherical bowl within wich convex domes are formed. This work is mainly focused on two topics. Firstly, the study of the making processes allows us to gain a better understanding of the work of the tuner in order to propose a model of the first step of steelpan making. Secondly, a vibration analysis of the steelpan, at the end of this process, is performed to understand its dynamics which is responsible of its particular tone. In the first part of the manuscript we study the evolution of the dynamical parameters during manufacturing. In particular, mode localization after note forming, strong variations of modal dampings, natural frequencies after burning and harmonic relationships after fine tuning are observed. The second part of the manuscript focusses on the first step of manufacturing during which the top of the barrel is hammered to obtain the spherical shell. The shell is analytically modeled as a nonlinear von Karman plate and the plastic strains are introduced as initial inelastic strains. The effect of the geometry and of the residual stress fields are separately quantified on the dynamical parameters of the structure in its final equilibrium state. The last part is concerned with the complex nonlinear dynamics of the steelpan at the end of the forming process. During normal playing, energy exchanges between modes are clearly identifiable: they result in a rich sound due to numerous internal resonances. Modal coupling are measured even for small amplitudes of vibrations. Original models of internal resonances are proposed
An upper bound for validity limits of asymptotic analytical approaches based on normal form theory by
Claude-Henri Lamarque(
)
1 edition published in 2012 in English and held by 2 WorldCat member libraries worldwide
1 edition published in 2012 in English and held by 2 WorldCat member libraries worldwide
Collective dynamics of weakly coupled nonlinear periodic structures by
Diala Bitar(
)
2 editions published in 2017 in English and held by 2 WorldCat member libraries worldwide
Although the dynamics of periodic nonlinear lattices was thoroughly investigated in the frequencyand time-space domains, there is a real need to perform profound analysis of the collectivedynamics of such systems in order to identify practical relations with the nonlinear energy localizationphenomenon in terms of modal interactions and bifurcation topologies. The principal goal ofthis thesis consists in exploring the localization phenomenon for modeling the collective dynamicsof periodic arrays of weakly coupled nonlinear resonators.An analytico-numerical model has been developed in order to study the collective dynamics ofa periodic coupled nonlinear oscillators array under simultaneous primary and parametric excitations,where the bifurcation topologies, the modal interactions and the basins of attraction havebeen analyzed. Arrays of coupled pendulums and electrostatically coupled nanobeams under externaland parametric excitations respectively were considered. It is shown that by increasing thenumber of coupled oscillators, the number of multimodal solutions and the distribution of the basinsof attraction of the resonant solutions increase. The model was extended to investigate the collectivedynamics of periodic nonlinear 2D arrays of coupled pendulums and spherical particles underbase excitation, leading to additional features, mainly larger bandwidth and important vibrationalamplitudes. A second investigation of this thesis consists in identifying the solitons associated tothe collective nonlinear dynamics of the considered arrays of periodic structures and the study oftheir stability
2 editions published in 2017 in English and held by 2 WorldCat member libraries worldwide
Although the dynamics of periodic nonlinear lattices was thoroughly investigated in the frequencyand time-space domains, there is a real need to perform profound analysis of the collectivedynamics of such systems in order to identify practical relations with the nonlinear energy localizationphenomenon in terms of modal interactions and bifurcation topologies. The principal goal ofthis thesis consists in exploring the localization phenomenon for modeling the collective dynamicsof periodic arrays of weakly coupled nonlinear resonators.An analytico-numerical model has been developed in order to study the collective dynamics ofa periodic coupled nonlinear oscillators array under simultaneous primary and parametric excitations,where the bifurcation topologies, the modal interactions and the basins of attraction havebeen analyzed. Arrays of coupled pendulums and electrostatically coupled nanobeams under externaland parametric excitations respectively were considered. It is shown that by increasing thenumber of coupled oscillators, the number of multimodal solutions and the distribution of the basinsof attraction of the resonant solutions increase. The model was extended to investigate the collectivedynamics of periodic nonlinear 2D arrays of coupled pendulums and spherical particles underbase excitation, leading to additional features, mainly larger bandwidth and important vibrationalamplitudes. A second investigation of this thesis consists in identifying the solitons associated tothe collective nonlinear dynamics of the considered arrays of periodic structures and the study oftheir stability
Backbone curves of coupled cubic oscillators in one-to-one internal resonance: bifurcation scenario, measurements and parameter
identification by
Arthur Givois(
)
1 edition published in 2020 in English and held by 2 WorldCat member libraries worldwide
1 edition published in 2020 in English and held by 2 WorldCat member libraries worldwide
Acoustique des instruments de musique by
Antoine Chaigne(
Book
)
1 edition published in 2013 in French and held by 2 WorldCat member libraries worldwide
This book, the first English-language translation of Acoustique des instruments de musique, Second Edition, presents the necessary foundations for understanding the complex physical phenomena involved in musical instruments. What is the function of the labium in a flute? Which features of an instrument allow us to make a clear audible distinction between a clarinet and a trumpet? With the help of numerous examples, these questions are addressed in detail. The authors focus in particular on the significant results obtained in the field during the last fifteen years. Their goal is to show that elementary physical models can be used with benefit for various applications in sound synthesis, instrument making, and sound recording. The book is primarily addressed to graduate students and researchers; however it could also be of interest for engineers, musicians, craftsmen, and music lovers who wish to learn about the basics of musical acoustics. Casts new light on the physics of musical instruments Includes up-to-date research published int he field of musical acoustics in the last fifteen years Outlines new methods developed in other fields such as complex modes and nonlinear normal modes Represents the only book on the physics of musical instruments to include practice exercises, catering to a broad audience of graduate students and researchers Brings the essential Acoustique des instruments de musique to an English audience for the first time
1 edition published in 2013 in French and held by 2 WorldCat member libraries worldwide
This book, the first English-language translation of Acoustique des instruments de musique, Second Edition, presents the necessary foundations for understanding the complex physical phenomena involved in musical instruments. What is the function of the labium in a flute? Which features of an instrument allow us to make a clear audible distinction between a clarinet and a trumpet? With the help of numerous examples, these questions are addressed in detail. The authors focus in particular on the significant results obtained in the field during the last fifteen years. Their goal is to show that elementary physical models can be used with benefit for various applications in sound synthesis, instrument making, and sound recording. The book is primarily addressed to graduate students and researchers; however it could also be of interest for engineers, musicians, craftsmen, and music lovers who wish to learn about the basics of musical acoustics. Casts new light on the physics of musical instruments Includes up-to-date research published int he field of musical acoustics in the last fifteen years Outlines new methods developed in other fields such as complex modes and nonlinear normal modes Represents the only book on the physics of musical instruments to include practice exercises, catering to a broad audience of graduate students and researchers Brings the essential Acoustique des instruments de musique to an English audience for the first time
Etude du mécanisme de résistance aux peptides antimicrobiens médié par un transporteur ABC couplé à un système de régulation
à deux composants chez Streptococcus pneumoniae by Aissatou Maty Diagne(
)
1 edition published in 2021 in French and held by 1 WorldCat member library worldwide
Antibiotic resistance is a growing threat to public health affecting many bacterial pathogens. To slow this phenomenon, antimicrobial peptides (AMPs), naturally synthesized and involved in immune defence of several organisms, are a promising therapeutic approach. However, bacteria present plenty mechanisms to thwart thes peptides action. One of the most important resistance mechanisms involves a close collaboration between an ABC transporter and a two-component regulatory system (TCS). To understand the mechanism of resistance to AMPs in Streptococcus pneumoniae, an important human pathogen, we identified the TCS associated with the ABC transporter of AMPs. TCS01 in collaboration with a BceAB-like ABC transporter detect and induc resistance to structurally-unrelated antimicrobial peptides but targeting undecaprenyl-pyrophosphate or lipid II, which are essential for peptidoglycan biosynthesis. Although the genes encoding TCS01 and the BceAB transporter are not located in the same gene cluster, the disruption of either of them equally sensitized S. pneumoniae to the same AMPs. We have shown by fluorescence and qPCR experiments that TCS01 regulates the expression of the BceAB transporter. To characterize the molecular mechanism of the BceAB transporter, we overexpressed and purified it from Escherichia coli. After reconstitution in liposomes, the transporter exhibits subtantial ATPase and GTPase activities which are stimulated by the AMPs substrates of the resistance system
1 edition published in 2021 in French and held by 1 WorldCat member library worldwide
Antibiotic resistance is a growing threat to public health affecting many bacterial pathogens. To slow this phenomenon, antimicrobial peptides (AMPs), naturally synthesized and involved in immune defence of several organisms, are a promising therapeutic approach. However, bacteria present plenty mechanisms to thwart thes peptides action. One of the most important resistance mechanisms involves a close collaboration between an ABC transporter and a two-component regulatory system (TCS). To understand the mechanism of resistance to AMPs in Streptococcus pneumoniae, an important human pathogen, we identified the TCS associated with the ABC transporter of AMPs. TCS01 in collaboration with a BceAB-like ABC transporter detect and induc resistance to structurally-unrelated antimicrobial peptides but targeting undecaprenyl-pyrophosphate or lipid II, which are essential for peptidoglycan biosynthesis. Although the genes encoding TCS01 and the BceAB transporter are not located in the same gene cluster, the disruption of either of them equally sensitized S. pneumoniae to the same AMPs. We have shown by fluorescence and qPCR experiments that TCS01 regulates the expression of the BceAB transporter. To characterize the molecular mechanism of the BceAB transporter, we overexpressed and purified it from Escherichia coli. After reconstitution in liposomes, the transporter exhibits subtantial ATPase and GTPase activities which are stimulated by the AMPs substrates of the resistance system
Reduced-order models for geometrically nonlinear vibrations of thin structures by
Yichang Shen(
)
1 edition published in 2021 in English and held by 1 WorldCat member library worldwide
When vibrating with large amplitudes, thin structures experience geometric nonlinearity due to the nonlinear relationship between strains and displacements. Because full-order nonlinear analysis on geometrically nonlinear models are computationally very expensive, the derivation of efficient reduced-order models (ROMs) has always been a topic of interest.In this thesis, nonlinear reduction methods for building ROMs with geometric nonlinearity in the framework of the Finite Element (FE) procedure, are investigated. Three non-intrusive nonlinear reduction methods are specifically investigated and systematically compared. They are: implicit condensation and expansion (ICE), modal derivatives (MD), and the reduction to invariant manifold. Theoretical analysis shows that the first two methods can give reliable results only if a slow/fast assumption between slave and master coordinates holds. On the other hand, reduction to invariant manifolds allows proposing a simulation-free reduction method that can be applied without restricting assumptions on the frequencies of the slave modes.Numerical comparisons and numerous applications to continuous structures discretized with the FE procedure, are given subsequently. For application of the invariant manifold-based method, the computation is based on a direct application of the normal form to the physical space and hence to the nodes of the FE mesh, a method recently developed. The examples show the advantages and drawbacks of each reduction method when deriving ROM, and the results of the theoretical comparison are validated.Finally, the analysis of the dynamics of a system with 1:2 internal resonance and cubic nonlinearity is given in the last part of the thesis. The real normal form of the problem is first derived. Then the solution branches of the problem are investigated and compared to simpler solutions with the dynamics truncated at order two. The divergent behaviour of the hardening/softening characteristics for single-mode reduction is investigated with this more complete model
1 edition published in 2021 in English and held by 1 WorldCat member library worldwide
When vibrating with large amplitudes, thin structures experience geometric nonlinearity due to the nonlinear relationship between strains and displacements. Because full-order nonlinear analysis on geometrically nonlinear models are computationally very expensive, the derivation of efficient reduced-order models (ROMs) has always been a topic of interest.In this thesis, nonlinear reduction methods for building ROMs with geometric nonlinearity in the framework of the Finite Element (FE) procedure, are investigated. Three non-intrusive nonlinear reduction methods are specifically investigated and systematically compared. They are: implicit condensation and expansion (ICE), modal derivatives (MD), and the reduction to invariant manifold. Theoretical analysis shows that the first two methods can give reliable results only if a slow/fast assumption between slave and master coordinates holds. On the other hand, reduction to invariant manifolds allows proposing a simulation-free reduction method that can be applied without restricting assumptions on the frequencies of the slave modes.Numerical comparisons and numerous applications to continuous structures discretized with the FE procedure, are given subsequently. For application of the invariant manifold-based method, the computation is based on a direct application of the normal form to the physical space and hence to the nodes of the FE mesh, a method recently developed. The examples show the advantages and drawbacks of each reduction method when deriving ROM, and the results of the theoretical comparison are validated.Finally, the analysis of the dynamics of a system with 1:2 internal resonance and cubic nonlinearity is given in the last part of the thesis. The real normal form of the problem is first derived. Then the solution branches of the problem are investigated and compared to simpler solutions with the dynamics truncated at order two. The divergent behaviour of the hardening/softening characteristics for single-mode reduction is investigated with this more complete model
Piano acoustics : string's double polarisation and piano source identification by
Jin Jack Tan(
)
1 edition published in 2017 in English and held by 1 WorldCat member library worldwide
The objective of this thesis is to improve the understanding of the acoustics of the piano in the context of physically-based sound synthesis. The manuscript is decomposed in three parts, the first two being devoted to the undertsanding of the origin of the double polarisation in piano string, while the third one is dedicated to the identification of sound sources of a complete piano.In the first part, the geometric (large-amplitude) nonlinearity is studied in order to understand if the nonlinear coupling can transfer energy to an initially non excited polarisation, thus leading to the double polarisation phenomenon. A multiple-scaleanalysis is conducted on a Kirchhoff-Carrier string model with fixed boundary conditions at both ends. Each polarisation is restrained to its fundamental mode, leading to two oscillors having nearly equal eigenfrequencies, and thus presenting a 1:1 internal resonance. The existence condition and stability criteria for double polarisation to occur are obtained and validated numerically based on the complete Kirchhoff-Carrier equations, as well as a more enriched third-order string model. Experiments are carried out on a monochord setup where the natural polarisation angles of the string, detuning between the two polarisations and its nonlinear behaviour are observed and identified.The second part is devoted to the string/bridge coupling. The degrees of freedom of the string are coupled to the bridge whose translational and rotational motions are respresented by a set of oscillators. The eigenfrequencies of various coupled systems are analysed. Numerical schemes are proposed and implemented where the string is solved via high-order finite-element method while the lumped bridge is solved analytically and coupled to the string by Lagrange multipliers. Experimentally, the string is strung over a bridge in a zig-zag configuration and excited vertically and horizontally. In both cases, double polarisation and double decay are observed and similar results are also obtained qualitatively in numerical models.The last part is devoted to a quantitative description of the vibroacoustic sources of a Bösendorfer 280VC-9 piano via operational transfer path analysis. The contribution of the soundboard, inner and outer rim, iron frame and lid are investigated in the frequency domain. It is found out that the soundboard is the primary contributor but the iron frame and the lid also play a significant role, especially at high frequencies
1 edition published in 2017 in English and held by 1 WorldCat member library worldwide
The objective of this thesis is to improve the understanding of the acoustics of the piano in the context of physically-based sound synthesis. The manuscript is decomposed in three parts, the first two being devoted to the undertsanding of the origin of the double polarisation in piano string, while the third one is dedicated to the identification of sound sources of a complete piano.In the first part, the geometric (large-amplitude) nonlinearity is studied in order to understand if the nonlinear coupling can transfer energy to an initially non excited polarisation, thus leading to the double polarisation phenomenon. A multiple-scaleanalysis is conducted on a Kirchhoff-Carrier string model with fixed boundary conditions at both ends. Each polarisation is restrained to its fundamental mode, leading to two oscillors having nearly equal eigenfrequencies, and thus presenting a 1:1 internal resonance. The existence condition and stability criteria for double polarisation to occur are obtained and validated numerically based on the complete Kirchhoff-Carrier equations, as well as a more enriched third-order string model. Experiments are carried out on a monochord setup where the natural polarisation angles of the string, detuning between the two polarisations and its nonlinear behaviour are observed and identified.The second part is devoted to the string/bridge coupling. The degrees of freedom of the string are coupled to the bridge whose translational and rotational motions are respresented by a set of oscillators. The eigenfrequencies of various coupled systems are analysed. Numerical schemes are proposed and implemented where the string is solved via high-order finite-element method while the lumped bridge is solved analytically and coupled to the string by Lagrange multipliers. Experimentally, the string is strung over a bridge in a zig-zag configuration and excited vertically and horizontally. In both cases, double polarisation and double decay are observed and similar results are also obtained qualitatively in numerical models.The last part is devoted to a quantitative description of the vibroacoustic sources of a Bösendorfer 280VC-9 piano via operational transfer path analysis. The contribution of the soundboard, inner and outer rim, iron frame and lid are investigated in the frequency domain. It is found out that the soundboard is the primary contributor but the iron frame and the lid also play a significant role, especially at high frequencies
Vibrations non linéaires de cordes avec contact unilatéral. Application aux instruments de musique by
Clara Issanchou(
)
1 edition published in 2017 in French and held by 1 WorldCat member library worldwide
Les contacts entre une corde vibrante et un obstacle unilatéral interviennent dans de nombreux instruments de musique tels que la tampoura, le sitar ou encore la basse électrique. Ils introduisent une forte non-linéarité dans le mouvement de la corde, qui se traduit notamment par d'importants transferts d'énergie. Dans ce manuscrit, une étude à la fois numérique et expérimentale du contact corde/obstacle est proposée. Trois types de schémas conservatifs sont développés. Ils s'appuient sur une description modale de la corde, ce qui permet un ajustement des fréquences propres et amortissements pour chaque mode. De plus, deux modèles de contact et frottement sont considérés, l'un régularisant et l'autre non. Des comparaisons à la solution analytique dans le cas d'un obstacle ponctuel sont menées et permettent une première validation des modèles. Des protocoles expérimentaux sont ensuite mis en place pour l'étude d'une corde isolée en présence d'un obstacle ponctuel, puis dans le cas d'une corde installée sur une basse électrique, munie ou non de frettes. Une forte concordance des signaux expérimentaux et numériques est observée sur des temps longs, montrant la capacité des modèles à rendre compte des éléments principaux observés expérimentalement. Enfin, une étude paramétrique est conduite dans le cas d'une basse munie de frettes, montrant l'influence de paramètres tels que la position de pincement de la corde et le réglage des frettes sur le son produit. Ces ajustements sont directement liés à des problématiques récurrentes et centrales rencontrées par les musiciens et les luthiers
1 edition published in 2017 in French and held by 1 WorldCat member library worldwide
Les contacts entre une corde vibrante et un obstacle unilatéral interviennent dans de nombreux instruments de musique tels que la tampoura, le sitar ou encore la basse électrique. Ils introduisent une forte non-linéarité dans le mouvement de la corde, qui se traduit notamment par d'importants transferts d'énergie. Dans ce manuscrit, une étude à la fois numérique et expérimentale du contact corde/obstacle est proposée. Trois types de schémas conservatifs sont développés. Ils s'appuient sur une description modale de la corde, ce qui permet un ajustement des fréquences propres et amortissements pour chaque mode. De plus, deux modèles de contact et frottement sont considérés, l'un régularisant et l'autre non. Des comparaisons à la solution analytique dans le cas d'un obstacle ponctuel sont menées et permettent une première validation des modèles. Des protocoles expérimentaux sont ensuite mis en place pour l'étude d'une corde isolée en présence d'un obstacle ponctuel, puis dans le cas d'une corde installée sur une basse électrique, munie ou non de frettes. Une forte concordance des signaux expérimentaux et numériques est observée sur des temps longs, montrant la capacité des modèles à rendre compte des éléments principaux observés expérimentalement. Enfin, une étude paramétrique est conduite dans le cas d'une basse munie de frettes, montrant l'influence de paramètres tels que la position de pincement de la corde et le réglage des frettes sur le son produit. Ces ajustements sont directement liés à des problématiques récurrentes et centrales rencontrées par les musiciens et les luthiers
Amortisseurs passifs non linéaires pour le contrôle de l'instabilité de flottement by
Arnaud Malher(
)
1 edition published in 2016 in French and held by 1 WorldCat member library worldwide
The aim of this thesis is to study the effect of passive nonlinear absorbers on the two degrees of freedom airfoil flutter. When an airfoil is subject to flutter instability, it oscillates increasingly until stabilizing on a limit cycle, the amplitude of which can be possibly substantial and thus damage the airfoil structure. The control has two main objectives : delay the instability and decrease the limit cycle amplitude. The flutter instability, and the post-flutter regime in particular, were studied first. A flutter experiment on a flat plate airfoil was conducted and the airfoil behavior was modeled, taking into account dynamic stall. Regarding the passive control, the first absorber studied was a hysteretic damper, realized using shape memory alloys springs. The characteristic of such dampers is their hysteretic restoring force, allowing them to dissipate a large amount of energy. Their main goal was thus to decrease the limit cycle amplitude caused by the flutter instability. This expected effect was observed and quantified both experimentally and numerically, using heuristic model. The second absorber studied was a nonlinear tuned vibration absorber. This absorber consists of a light mass attached to the airfoil through a spring having both a linear and a cubic stiffness. The role of the linear part of such absorber was to repel the instability threshold, while the aim of the nonlinear part was to decrease the limit cycle amplitude. It was found, analytically and numerically, that the instability threshold is substantially shifted by this absorber, whereas the limit cycle amplitude decrease is relatively modest
1 edition published in 2016 in French and held by 1 WorldCat member library worldwide
The aim of this thesis is to study the effect of passive nonlinear absorbers on the two degrees of freedom airfoil flutter. When an airfoil is subject to flutter instability, it oscillates increasingly until stabilizing on a limit cycle, the amplitude of which can be possibly substantial and thus damage the airfoil structure. The control has two main objectives : delay the instability and decrease the limit cycle amplitude. The flutter instability, and the post-flutter regime in particular, were studied first. A flutter experiment on a flat plate airfoil was conducted and the airfoil behavior was modeled, taking into account dynamic stall. Regarding the passive control, the first absorber studied was a hysteretic damper, realized using shape memory alloys springs. The characteristic of such dampers is their hysteretic restoring force, allowing them to dissipate a large amount of energy. Their main goal was thus to decrease the limit cycle amplitude caused by the flutter instability. This expected effect was observed and quantified both experimentally and numerically, using heuristic model. The second absorber studied was a nonlinear tuned vibration absorber. This absorber consists of a light mass attached to the airfoil through a spring having both a linear and a cubic stiffness. The role of the linear part of such absorber was to repel the instability threshold, while the aim of the nonlinear part was to decrease the limit cycle amplitude. It was found, analytically and numerically, that the instability threshold is substantially shifted by this absorber, whereas the limit cycle amplitude decrease is relatively modest
Actionnement des poutres bistables : modélisations statique et dynamique, optimisations et études expérimentales by
Achref Amor(
)
1 edition published in 2020 in French and held by 1 WorldCat member library worldwide
The work carried out during this thesis focused on the study of the behavior of a bistable buckled beam subjected to several types of actuations. The static and dynamic aspects of switching mecanism are analyzed. The kinematic model used is the Elastica model. This latter is adapted to take into account deformations, displacements and rotations of significant amplitudes. In addition, the extensible nature of the beam is considered. The static part is devoted to the study of bifurcation diagrams for three types of actuations: ponctual force, piezoelectric elements and Laplace forces. For each of these technologies, an optimization procedure is implemented. At the end of the static part, experimental tests are carried out. They made it possible to validate the model in the case of actuation via Laplace forces. In the dynamic part a new model is developed to simulate the dynamic behavior of the beam. This model taking into account three modes of buckling. We excited the beam via a sinusoidal point force. The influence of several parameters on the response of the beam is discussed. In particular, we established that bringing the beam into resonance reduces the switching force. In addition, the analysis of the diagrams of the Poincaré sections allows us to understand the origins of the chaotic behavior of the beam. Experimental tests were carried out at the end of the dynamic part in order to validate the model. The results issued from these studies are used to design a new technology for actuating Braille devices. This technology is based on bistable beams. The possibility of actuating these structures via electromagnetic forces and via piezoelectric elements is discussed
1 edition published in 2020 in French and held by 1 WorldCat member library worldwide
The work carried out during this thesis focused on the study of the behavior of a bistable buckled beam subjected to several types of actuations. The static and dynamic aspects of switching mecanism are analyzed. The kinematic model used is the Elastica model. This latter is adapted to take into account deformations, displacements and rotations of significant amplitudes. In addition, the extensible nature of the beam is considered. The static part is devoted to the study of bifurcation diagrams for three types of actuations: ponctual force, piezoelectric elements and Laplace forces. For each of these technologies, an optimization procedure is implemented. At the end of the static part, experimental tests are carried out. They made it possible to validate the model in the case of actuation via Laplace forces. In the dynamic part a new model is developed to simulate the dynamic behavior of the beam. This model taking into account three modes of buckling. We excited the beam via a sinusoidal point force. The influence of several parameters on the response of the beam is discussed. In particular, we established that bringing the beam into resonance reduces the switching force. In addition, the analysis of the diagrams of the Poincaré sections allows us to understand the origins of the chaotic behavior of the beam. Experimental tests were carried out at the end of the dynamic part in order to validate the model. The results issued from these studies are used to design a new technology for actuating Braille devices. This technology is based on bistable beams. The possibility of actuating these structures via electromagnetic forces and via piezoelectric elements is discussed
Méthodologie pour génération de modèles réduits dynamiques multiphysiques : application aux open rotors by
Hadrien Tournaire(
)
1 edition published in 2017 in French and held by 1 WorldCat member library worldwide
La conception d'un produit industriel requiert parfois des simulations afin de prédire le comportement du produit en question. En pratique ce type de simulations peut être réalisé en utilisant la méthode des éléments finis, cependant la précision et le niveau de détail souhaité génèrent des modèles difficiles à évaluer. En outre, le caractère itératif présent dans de nombreuses conceptions accentue le ralentissement induit par ces simulations couteuses en temps de calculs. Afin de pallier ce problème, une démarche de réduction de modèle est souhaitée par le partenaire industriel. Les grands axes de travail sur cette méthode sont : la recherche d'une haute compacité, la prise en compte de non-linéarités de grands déplacements et l'évaluation de l'amortissement dans les liaisons du système due au phénomène de contact-friction
1 edition published in 2017 in French and held by 1 WorldCat member library worldwide
La conception d'un produit industriel requiert parfois des simulations afin de prédire le comportement du produit en question. En pratique ce type de simulations peut être réalisé en utilisant la méthode des éléments finis, cependant la précision et le niveau de détail souhaité génèrent des modèles difficiles à évaluer. En outre, le caractère itératif présent dans de nombreuses conceptions accentue le ralentissement induit par ces simulations couteuses en temps de calculs. Afin de pallier ce problème, une démarche de réduction de modèle est souhaitée par le partenaire industriel. Les grands axes de travail sur cette méthode sont : la recherche d'une haute compacité, la prise en compte de non-linéarités de grands déplacements et l'évaluation de l'amortissement dans les liaisons du système due au phénomène de contact-friction
Méthodes numériques pour les systèmes dynamiques non linéaires : application aux instruments de musique auto-oscillants by
Sami Karkar(
)
1 edition published in 2012 in French and held by 1 WorldCat member library worldwide
Periodic solutions of nonlinear dynamical systems are the focus of this work. We compute periodic solutions through a BVP formulation, solved with two numerical methods: - a spectral method, in the frequency domain: the hogh-order Harmonic Balance Method, using a quadratic formulation of the original equations. We also propose an extension to nonrational nonlinearities. - a pseudo-spectral method, in the time domain : the arthogonal collocation at Gauss point, with piece-wise polynomial interpolation. Both methods lead to a system of nonlinear algebraic equations, and its solutions are computed by a continuation algorithm : the Asymptotic Numerical Method. These methods are embeded in the numerical package MANLAB, together with a linear stability analysis. Application We then apply these methods to physical models of several instruments : a clarinet, a saxophone, and a violin. The clarinet model contains a non-smooth contact between the reed and the mouthpiece. The study focuses on the evolution of frequency, loudness, and spectrum along the branch of periodic solutions when varying the mouth pressure. The saxophone model is very similar, but an experimental characterization of the bore is used in that case. Finally, the violin model with a non-smooth Coulomb contact law and a simplified resonator is studied, showing the variety of models that can be treated using this method
1 edition published in 2012 in French and held by 1 WorldCat member library worldwide
Periodic solutions of nonlinear dynamical systems are the focus of this work. We compute periodic solutions through a BVP formulation, solved with two numerical methods: - a spectral method, in the frequency domain: the hogh-order Harmonic Balance Method, using a quadratic formulation of the original equations. We also propose an extension to nonrational nonlinearities. - a pseudo-spectral method, in the time domain : the arthogonal collocation at Gauss point, with piece-wise polynomial interpolation. Both methods lead to a system of nonlinear algebraic equations, and its solutions are computed by a continuation algorithm : the Asymptotic Numerical Method. These methods are embeded in the numerical package MANLAB, together with a linear stability analysis. Application We then apply these methods to physical models of several instruments : a clarinet, a saxophone, and a violin. The clarinet model contains a non-smooth contact between the reed and the mouthpiece. The study focuses on the evolution of frequency, loudness, and spectrum along the branch of periodic solutions when varying the mouth pressure. The saxophone model is very similar, but an experimental characterization of the bore is used in that case. Finally, the violin model with a non-smooth Coulomb contact law and a simplified resonator is studied, showing the variety of models that can be treated using this method
Modeling and characterization of nonlinear phenomena in circular capacitive micromachined ultrasonic transducers with geometrical
imperfections by
Aymen Jallouli(
)
1 edition published in 2018 in English and held by 1 WorldCat member library worldwide
Micro Electro Mechanical Systems (MEMS) have attracted the interest of scientists and engineers thanks to the variety of their applications and their significant roles in our real life. One of the most important microsystems is the capacitive micromachined ultrasonic transducer (CMUT), which is used for transmitting ultrasonic waves, for instance in medical imaging and therapy. In such applications, a high-transmitted acoustic power is needed which implies driving the CMUT in the nonlinear regime. Moreover, from a manufacturing point of view, the fabrication of a CMUT with a flat surface is extremely difficult even with the recent advances in the fabrication process. Modeling this type of microsystem while including the main sources of nonlinearities and geometric imperfections is a challenging step in understanding its static and dynamic behavior.In this thesis, a multiphysics model of imperfect CMUTs is developed taking into account the geometric and electrostatic nonlinearities. The governing equations of motions are derived from the von Kármán plate theory and spatially discretized using the Differential Quadrature Method (DQM). For the static response, numerical simulations and experimental characterizations have been conducted on flat and curved CMUTs, showing that a positive initial deflection leads to an increase in the pull-in voltage. The nonlinear dynamic behavior of a CMUT is studied by discretizing the time variable using the Finite Difference Method (FDM). The nonlinear frequency and force responses have been determined by combining FDM with the arclength continuation technique. It is shown that the CMUT can exhibit a hardening or softening behavior depending on the DC voltage. An experimental validation of the numerical model is performed for the case of flat and curved microplates. We demonstrate that the geometric imperfection modifies the nonlinear frequency response of a CMUT from hardening to softening, increases its bistability domain and permits the tuning of its bifurcation topology.The numerical model is extended to investigate the effect of an air film on the dynamic behavior of the microplate by coupling the nonlinear mechanical equations with the Reynolds equation. The complex resonance frequencies of the multi-physical problem are determined by solving the damped linear system. An experimental and numerical validation of the model is performed by determining the resonance frequencies at several static pressures. We demonstrate that the air film is able to modify the dynamic response of the CMUT by adding stiffness and damping. By decreasing the static pressure, the resonance frequency of the coupled problem decreases and becomes closer to the natural resonance frequency of the microplate. Moreover, the frequency response of the system becomes nonlinear due the decrease in the damping coefficient. At atmospheric pressure, the softening type behavior of the CMUT is obtained by applying high excitation levels. The presented numerical model is a very efficient tool to understand the nonlinear dynamic behavior CMUTs and to enhance their performances
1 edition published in 2018 in English and held by 1 WorldCat member library worldwide
Micro Electro Mechanical Systems (MEMS) have attracted the interest of scientists and engineers thanks to the variety of their applications and their significant roles in our real life. One of the most important microsystems is the capacitive micromachined ultrasonic transducer (CMUT), which is used for transmitting ultrasonic waves, for instance in medical imaging and therapy. In such applications, a high-transmitted acoustic power is needed which implies driving the CMUT in the nonlinear regime. Moreover, from a manufacturing point of view, the fabrication of a CMUT with a flat surface is extremely difficult even with the recent advances in the fabrication process. Modeling this type of microsystem while including the main sources of nonlinearities and geometric imperfections is a challenging step in understanding its static and dynamic behavior.In this thesis, a multiphysics model of imperfect CMUTs is developed taking into account the geometric and electrostatic nonlinearities. The governing equations of motions are derived from the von Kármán plate theory and spatially discretized using the Differential Quadrature Method (DQM). For the static response, numerical simulations and experimental characterizations have been conducted on flat and curved CMUTs, showing that a positive initial deflection leads to an increase in the pull-in voltage. The nonlinear dynamic behavior of a CMUT is studied by discretizing the time variable using the Finite Difference Method (FDM). The nonlinear frequency and force responses have been determined by combining FDM with the arclength continuation technique. It is shown that the CMUT can exhibit a hardening or softening behavior depending on the DC voltage. An experimental validation of the numerical model is performed for the case of flat and curved microplates. We demonstrate that the geometric imperfection modifies the nonlinear frequency response of a CMUT from hardening to softening, increases its bistability domain and permits the tuning of its bifurcation topology.The numerical model is extended to investigate the effect of an air film on the dynamic behavior of the microplate by coupling the nonlinear mechanical equations with the Reynolds equation. The complex resonance frequencies of the multi-physical problem are determined by solving the damped linear system. An experimental and numerical validation of the model is performed by determining the resonance frequencies at several static pressures. We demonstrate that the air film is able to modify the dynamic response of the CMUT by adding stiffness and damping. By decreasing the static pressure, the resonance frequency of the coupled problem decreases and becomes closer to the natural resonance frequency of the microplate. Moreover, the frequency response of the system becomes nonlinear due the decrease in the damping coefficient. At atmospheric pressure, the softening type behavior of the CMUT is obtained by applying high excitation levels. The presented numerical model is a very efficient tool to understand the nonlinear dynamic behavior CMUTs and to enhance their performances
Contribution to the study of damping in bolted structures by
Marco Rosatello(
)
1 edition published in 2019 in English and held by 1 WorldCat member library worldwide
La dynamique des structures assemblées est un sujet de recherche actuel. En particulier, une prédiction correcte de l'amortissement apporté par les liaisons vissés est devenu une condition essentiel pour un certain nombre d'applications, comme par exemple les avions et les véhicules spatiaux. En effet, pour ces applications, l'utilisation de matériaux avec un coefficient d'amortissement plus élevée, comme des matériaux visco-élastiques, est limité par les conditions de fonctionnement.Ces travaux apportent deux contributions principales. La première porte sur la phase de conception et modélisation, avec la création d'un système de connecteurs pour la reproduction des comportements normal et tangentiel d'une liaisons vissée. Cela est accomplie en considérant seulement les données physiques de la liaison et des surfaces en contact.La deuxième contribution concerne l'évaluation des propriétés dynamiques non-linéaires des assemblages. Un set d'outils de post-traitement utilisant le filtre de Kalman est développé pour réaliser une analyse modale non-linéaire pour les types d'essais les plus communs: les essais aux chocs, les essais en balayage sinus, et les essais en sinus aléatoire.Les méthodes développées ont été appliqués et évaluées sur une structure boulonnée réel, en soulignant les avantages et les inconvénients. Notamment, le filtre de Kalman permet une meilleure précision sur les paramétrés identifiés, mais le procédé d'initialisation du filtre est le problème principal. Une automatisation partiel de l'initialisation est prévu, ainsi que des conseils pratiques grâce à l'expérience acquise sur le sujet
1 edition published in 2019 in English and held by 1 WorldCat member library worldwide
La dynamique des structures assemblées est un sujet de recherche actuel. En particulier, une prédiction correcte de l'amortissement apporté par les liaisons vissés est devenu une condition essentiel pour un certain nombre d'applications, comme par exemple les avions et les véhicules spatiaux. En effet, pour ces applications, l'utilisation de matériaux avec un coefficient d'amortissement plus élevée, comme des matériaux visco-élastiques, est limité par les conditions de fonctionnement.Ces travaux apportent deux contributions principales. La première porte sur la phase de conception et modélisation, avec la création d'un système de connecteurs pour la reproduction des comportements normal et tangentiel d'une liaisons vissée. Cela est accomplie en considérant seulement les données physiques de la liaison et des surfaces en contact.La deuxième contribution concerne l'évaluation des propriétés dynamiques non-linéaires des assemblages. Un set d'outils de post-traitement utilisant le filtre de Kalman est développé pour réaliser une analyse modale non-linéaire pour les types d'essais les plus communs: les essais aux chocs, les essais en balayage sinus, et les essais en sinus aléatoire.Les méthodes développées ont été appliqués et évaluées sur une structure boulonnée réel, en soulignant les avantages et les inconvénients. Notamment, le filtre de Kalman permet une meilleure précision sur les paramétrés identifiés, mais le procédé d'initialisation du filtre est le problème principal. Une automatisation partiel de l'initialisation est prévu, ainsi que des conseils pratiques grâce à l'expérience acquise sur le sujet
Percussion instrument modelling in 3D : sound synthesis through time domain numerical simulation by
Alberto Torin(
)
1 edition published in 2016 in English and held by 1 WorldCat member library worldwide
1 edition published in 2016 in English and held by 1 WorldCat member library worldwide
Cinétiques d'endommagementà différentes échelles d'un acier austénitique inoxydable en fatigue à amplitude constante
et variable by Ammar Ould Amer(
Book
)
in French and held by 1 WorldCat member library worldwide
This study focuses on the characterization of plastic fatigue damage process of an austenitic stainless steel. The aim is to clarify the nature and proportions of the different stages of damage in the life of the material. Interrupted fatigue tests were established to monitor the evolution of the damage and to propose a description. At each stop, surface observations were performed for different amplitudes total strain. These observations have been completed by monitoring acoustic emission. Fatigue tests under constants amplitudes loading highlight three stages of damage. A model was proposed and compared to results obtained in fatigue under variables amplitudes loading
in French and held by 1 WorldCat member library worldwide
This study focuses on the characterization of plastic fatigue damage process of an austenitic stainless steel. The aim is to clarify the nature and proportions of the different stages of damage in the life of the material. Interrupted fatigue tests were established to monitor the evolution of the damage and to propose a description. At each stop, surface observations were performed for different amplitudes total strain. These observations have been completed by monitoring acoustic emission. Fatigue tests under constants amplitudes loading highlight three stages of damage. A model was proposed and compared to results obtained in fatigue under variables amplitudes loading
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Related Identities
- École nationale supérieure de techniques avancées (Palaiseau, Essonne) Other Degree grantor
- Université Pierre et Marie Curie (Paris / 1971-2017) Degree grantor
- SpringerLink (Online service) Other
- Chaigne, Antoine Thesis advisor Author
- Lamarque, Claude-Henri (1960-....). Other Opponent Author
- Thomas, Olivier
- Monteil, Mélodie Author
- Université Paris-Saclay (2015-2019) Other Degree grantor
- Gilbert, Joël Other Opponent
- École doctorale Sciences mécaniques et énergétiques, matériaux et géosciences (Gif-sur-Yvette, Essonne / 2015-....).
Other