Дисертації з теми "Coupe – Vibrations"
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Segreti, Michel Dudzinski Daniel. "Vibrations en coupe orthogonale Modélisation, étude de stabilité et validation expérimentale /." Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2002/Segreti.Michel.SMZ0201.pdf.
Segreti, Michel. "Vibrations en coupe orthogonale : Modélisation, étude de stabilité et validation expérimentale." Metz, 2002. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2002/Segreti.Michel.SMZ0201.pdf.
Bisu, Claudiu-Florinel. "Etude des vibrations auto-entretenues en coupe tridimensionnelle : nouvelle modélisation appliquée au tournage." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2007. http://tel.archives-ouvertes.fr/tel-00274647.
Pour remédier à ce phénomène en tournage des matériaux, une étude expérimentale originale exploitant la notion de torseur d'efforts est mise en place pour déterminer, très précisément, le comportement dynamique du système usinant (pièce/outil/machine). Les principaux paramètres relatifs au comportement dynamique du système usinant sont identifiés. La localisation des déplacements de la pointe de l'outil dans un plan caractéristique est démontrée. L'existence de ce plan et les corrélations avec les caractéristiques élastiques du système usinant permettent de simplifier le modèle dynamique 3D et de proposer un modèle en accord avec les résultats expérimentaux tout en restant dans une configuration tridimensionnelle de la coupe.
La simulation numérique issue de ce modèle simplifié fournit des résultats en bon accord avec l'expérience.
Bisu, Claudiu Florinel. "Etude des vibrations auto-entretenues en coupe tridimensionnelle : nouvelle modélisation appliquée au tournage." Bordeaux 1, 2007. http://www.theses.fr/2007BOR13375.
Yaqub, Sajid. "Proposition d'une démarche pour identifier les efforts de coupe en présence de talonnage." Paris, ENSAM, 2010. http://www.theses.fr/2010ENAM0056.
The process damping results from the interference between tool clearance face and the workpiece generated surface and affects the stability of a machining process. Therefore it is necessary to take this phenomenon into consideration during the simulation of machining process. This thesis work presents a practical method for identification, modelling, and numerical simulation of process damping during machining of a workpiece. A special fixture has been used which creates the vibrations conditions necessary to generate the interference between tool clearance face and the specifically designed workpiece. The modelling of process damping is based on the numerical calculation of the interference volume between tool clearance face and the workpiece generated surface. The tool and workpiece geometries are represented by z-buffers whose relative positions at each instant permit to evaluate numerically the interference volume. The process damping coefficients are then estimated by minimization of the error between measured cutting force and the simulated cutting forces
Chen, Shouyi. "Caractérisation de la dynamique de coupe en usinage." Compiègne, 1996. http://www.theses.fr/1996COMPD904.
Ladonne, Mathieu. "Modélisation du procédé de perçage assisté par vibrations forcées : prise en compte de l’environnement Pièce-Outil-Machine." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0006.
Vibrations assisted drilling is a process which ensures chip shape control in order to increase reliability during drilling operations. The adding of axial oscillation, controlled with amplitude and frequency, introduce two new parameters which must determinate according to the conventional parameters (feed and speed rotation). The optimal setting of vibrations assisted drilling is not obvious. To provide an optimization-tool of the process, a new model which take into account the “Tool-Workpiece-Machine” environment, is proposed. Drill geometry, Tool-Workpiece interactions and dynamic behavior of the Machine are incorporated in the model. Tis specificity allows adjusting behavior of the process with the case of application. An identification methodology is presented to characterize the environment. Simulation’s results and experimental results are compared to validate the model. This model thus allows predicting process behavior in order to optimize the operational parameters
Belguith, Rami. "Effets du comportement de la machine et des paramètres d'usinage sur la topographie des surfaces obtenues par fraisage à grande vitesse avec des fraises à bout sphérique monoblocs." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0127.
The optimization of the cutting parameters in high-speed machining requires the consideration of the machining errors in the modeling of the cutting forces and the surface topography. Therefore, the present study deals with the analysis of the effect of cutting parameters and machining errors on the surface topography of milled surfaces with a ball-end mill. The tool geometry was modeled taking into account all the machining errors such as runout, bending, vibrations and wear. Then, the Cutter Workpiece Engagement region 'CWE ', the cutting width and the uncut chip thickness were modeled taking into account the trace of the previous tooth. Subsequently, thermomechanical modeling of cutting forces in the milling process with a ball-end tool is made considering these errors. Finally, an analysis of the topography according to all these parameters and machining errors was carried out based on experimental validation
Kibbou, El Mehdi. "Contribution à la modélisation thermomécanique des vibrations en coupe oblique et à l'établissement d'un plan optimal de maintenance intégré à la production tenant compte des conditions d'usinage." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0234.
In this study, we are interested in a machining production system which is one of the manufacturing processes most adopted by the various mechanical industries (automotive, aviation…etc.). The objective of this multidisciplinary thesis (Mechanics and Industrial Engineering) is double: (1) the development of a new thermomechanical model of oblique cutting in dry machining and (2) the maximization of profit in order to establish a strategy production and a preventive maintenance plan.The coupling between the machining operation and the part "simultaneous optimization of production and maintenance costs" is done by considering the effect of cutting conditions on the generated surface quality and on the tool wear. In the proposed approach, wear is taken into account through Taylor's empirical law and the machined surface quality is predicted via a new model of vibrations in oblique cutting.The first objective of this work concerns the development of a new thermomechanical model of the oblique cutting with vibration. In this analytical cutting model, the vibratory system is assimilated to a system with a single degree of freedom in the tool feed direction. We take into account the coupling between tool oscillations, the thermomechanical process of chip formation as well as the regenerative effect. The latter results from the variation in the material quantity to be machined between two successive passes. The coupling between all of these mechanisms makes the problem to be solved strongly nonlinear. A resolution algorithm making it possible to reduce the computation time has been implemented.The second objective of the thesis is achieved through the development of an analytical model where the optimization consists in maximizing a profit integrating selling price of finished product, production and maintenance costs. We note the originality of this part consists in considering the impact of the machining conditions, especially the cutting speed, on the production durations and costs, the quality of the machined parts as well as the degradation of the production system. The impact of machining conditions on three fundamental aspects is therefore considered simultaneously for the "simultaneous optimization of production and maintenance costs" part. The first concerns the impact of machining conditions on production time and costs. The second concerns the impact on the degradation of the machining system and therefore on the optimal maintenance plan to be adopted. The third concerns the impact on the quality of the output product which directly affects the selling costs and more specifically the total profit. These interactions are taken into account through the development of an analytical model to establish an optimal integrated production maintenance plan for the machining system, illustrated by the optimal switching date for changing cutting speed and the optimal numbers of batches to produce before every preventive maintenance action for every production phase. Every production phase is characterized by a cutting speed
Castro, Martinez Luis Ricardo. "Identification des sources de vibration en usinage : étude expérimentale et numérique." Metz, 2006. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2006/Castro_Martinez.Luis_Ricardo.SMZ0624.pdf.
The main objective of this project is furnishing information to clarify the vibrations physics in machining from orthogonal cutting. First chapter contains the machining process characterisation by means of cutting forces. We evaluate the piezoelectric dynamometers in frequency domain and the influence of assembly components. These evaluations reveal the dynamic measurements problems. At the end of this part, we propose a correction method of piezoelectric dynamometer measurements to frequencies higher than dynamometer bandwidth. Also, we present an application of the method. Second chapter comprises the understanding of vibration sources. We analyse specially the segmented chip formation because its excitation role is not clear in literature. Also, we consider the effects of regenerative excitations, which depend of interaction between cutting conditions and machine-tool dynamic response. Third chapter includes the experimental identification of vibration sources during machining. We have identified and characterized the segmented chip formation and the machine-tool dynamic
Motta, Mariane Prado. "Contribution à l’étude de systèmes de surveillance de l'usinage basés sur des méthodes d‘apprentissage machine et des mesures de vibrations, efforts et température de coupe." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0296.
Machining is an economically important manufacturing process that relies on the use of a sharpened cutting tool to mechanically cut and remove material from a part to achieve a desired geometry. Given the ever-increasing demands for quality, product variability and cost reduction, tool condition and workpiece quality monitoring systems based on artificial intelligence (AI) techniques are a potential solution are a potential solution for a more reliable and economical manufacturing processes. Recent developments in the field of AI, have shown great potential to transform the manufacturing domain with advanced tools dedicated to data analysis and modeling. In particular, supervised machine learning (ML) algorithms are a powerful tool for modeling complex relationships between input and output variables based on a dataset containing examples, i.e., input-output pairs. Nevertheless, one of the main drawbacks of these modeling techniques is that a large amount of data, usually obtained through experiments (often long and expensive to perform), is required to train accurate and reliable models. This fact limits the applicability of these types of models in an industrial context. Considering this context, this study aims to contribute to the identification of methodologies for the development of ML models dedicated to machining monitoring within industrial conditions, in which time and resources for the realization of experiments are often limited. For this purpose, it is considered in this study that, although experiments can be onerous, in the industry it is common that, before starting large scale machining productions with a new tool or material, setup experiments are performed to determine the most appropriate cutting parameters to perform that production. Given this need (or recommendation), it will be investigated in this thesis, the predictive performances that can be achieved if data, obtained from these tuning experiments, are used to generate predictive models for machining monitoring. More precisely, setting experiments from the standardized methodology Couple Tool-Material protocol (NF E 66-520) are considered. In an effort to obtain good predictive performance with a limited amount of experimental data, sensors for measuring cutting forces, temperature and vibrations are chosen as instrumentation for the monitoring system to be developed, given its close relationship with the kinematics of the machining process. In this matter, special attention is given to the feature engineering step. That is, the process of transforming the available raw data, for example, the signals recorded by the sensors, into features, i.e., information, that more accurately represent the problem underlying the predictive model. Finally, since in the industry the changes in cutting tool reference can occur quite often, it will also be investigated whether the models developed for a given target tool can be applied to other slightly different tools (variations on nose radius, substrate and coating) and whether, for the training of ML models, the use of larger databases, but containing observations related not only to the target tool but also to other tools slightly different from it, will be more advantageous, compared to the use of a smaller database specific to the target tool
Ait, Sghir Khalid. "Contribution de la cyclostationnarité et de l'identification aveugle au diagnostic des outils de coupe." Thesis, Saint-Etienne, 2010. http://www.theses.fr/2010STET4012.
The identification of the state of a cutting tool is important in any metal cutting process. An additional cost - in terms of scrapped components, machine tool breakage and unscheduled downtime - occurs as a result of tool defects. The thesis objective is the cutting tool vibration analysis of a milling operation for the diagnosis of their state of degradation. In the first part, the possibilities offered by the synchronous statistics, applied to vibration signal captured from a milling process, are studied to examine the cutting tool condition. The processed vibration signals are cyclostationary, i.e their statistical properties are periodic. Taking into account this property, the use of descriptors able to characterize the process, in conjunction with the kinematics of the mechanical machining operation. Furthermore, when combined with the angular sampling, the cyclostationarity led to the proposed synchronous statistical estimators convenient to implement. First order and second order synchronous statistics, the spectral correlation and the cyclic bispectrum are defined with their interpretations and estimators. A model of milling vibration signal is given. This model aims to demonstrate the cyclostationarity of the signals. The use of these indicators is illustrated on real signals and compared with conventional indicators for diagnosing degradation of cutting tools.In the second part, the blind deconvolution of the impulse response of a cyclostationary process is
Amri, Mohamed. "Étude expérimentale et théorique de l’effet de la vitesse de coupe sur la forabilité des roches sous pression de boue." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM095.
The optimization of the drilling practice requires a better understanding of drillstring harmful vibrations such as stick-slip. This form of torsional vibrations is a typical problem of PDC (Polycristalline Diamond Compact) drillbits. It can reduce the rate of penetration drastically and can raise fatigue of the drilling devices. Many attempts were carried out in the last years in order to determine the causes of stick-slip phenomenon. Field observations show that torque on bit decreases as a function of bit velocity during stick-slip oscillations. Hence, it is widely believed that this decreasing relationship is the root cause of stick-slip.The purpose of this work is to examine cutting speed influence on rock drillability as a function of operating conditions and hydromechanical properties of the drilled formation. For this, a set of drilling tests was performed in three sedimentary rocks of different permeability using a full scale PDC drillbit and a single PDC cutter. In the first step, dry tests were carried out at atmospheric pressure. As previously observed in literature, single-cutter tests showed that drilling forces increase with cutting velocity. In a second step, we performed the same experiments at 20 MPa bottom-hole pressure. It appears that rate effect on cutting forces in the medium and low-permeability rocks is relatively low. By contrast, rate effect in the highly permeable rock increases by one order of magnitude in comparison with dry experiments.In order to understand this phenomenon, a steady state solution of the cutting model is derived in the framework of the theory of poroelastoplasticity. The problem is firstly solved analytically using some assumptions derived from previous works. Then, a numerical resolution based on finite element method is presented to solve the fully coupled problem ensuring the satisfaction of poro-material physics basic equations. Using these two different approaches, we show that pore pressure in shear-dilatant rocks decreases as a function of cutting velocity depending on rock permeability and interstitial fluid properties. This change has a hardening effect resulting in an increase of rock drilling resistance. Comparison between theory and experience shows good agreements
Amri, Mohamed. "Étude expérimentale et théorique de l’effet de la vitesse de coupe sur la forabilité des roches sous pression de boue." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM095.
The optimization of the drilling practice requires a better understanding of drillstring harmful vibrations such as stick-slip. This form of torsional vibrations is a typical problem of PDC (Polycristalline Diamond Compact) drillbits. It can reduce the rate of penetration drastically and can raise fatigue of the drilling devices. Many attempts were carried out in the last years in order to determine the causes of stick-slip phenomenon. Field observations show that torque on bit decreases as a function of bit velocity during stick-slip oscillations. Hence, it is widely believed that this decreasing relationship is the root cause of stick-slip.The purpose of this work is to examine cutting speed influence on rock drillability as a function of operating conditions and hydromechanical properties of the drilled formation. For this, a set of drilling tests was performed in three sedimentary rocks of different permeability using a full scale PDC drillbit and a single PDC cutter. In the first step, dry tests were carried out at atmospheric pressure. As previously observed in literature, single-cutter tests showed that drilling forces increase with cutting velocity. In a second step, we performed the same experiments at 20 MPa bottom-hole pressure. It appears that rate effect on cutting forces in the medium and low-permeability rocks is relatively low. By contrast, rate effect in the highly permeable rock increases by one order of magnitude in comparison with dry experiments.In order to understand this phenomenon, a steady state solution of the cutting model is derived in the framework of the theory of poroelastoplasticity. The problem is firstly solved analytically using some assumptions derived from previous works. Then, a numerical resolution based on finite element method is presented to solve the fully coupled problem ensuring the satisfaction of poro-material physics basic equations. Using these two different approaches, we show that pore pressure in shear-dilatant rocks decreases as a function of cutting velocity depending on rock permeability and interstitial fluid properties. This change has a hardening effect resulting in an increase of rock drilling resistance. Comparison between theory and experience shows good agreements
Orefice, Giovanni. "Description par mobilités énergétiques des échanges vibratoires dans les systèmes couple." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0109.
The energetic mobility is defined: it links the active injected power in a frequency band at a given point on a structure to the squared velocity level at another point. On a single structure it can be used to add the contributions of several active power injection and obtain the frequency averaged squared velocity level at any point. On an assembly it allows predicting the local frequency averaged squared velocity level after coupling using those on the substructures before coupling. The energetic mobility between two uncoupled points is almost invariant after coupling the structure and the energetic mobility is asymptotically invariant if one adds a mass at the injection point. The concept of active power sources in a frequency band is also defined and declaimed. The energetic mean mobility approach (EMMA) allows one to make local energetic predictions using exclusively frequency band averaged quantities. Numeric tests of multipoint (rigid or elastic and dissipative) coupling of homogeneous and heterogeneous plates follow, with the study of the different errors of the method and with an experiment on plate and cylinder assemblies
Castro, Martinez Luis Ricardo Lipinski Paul Vieville Pascal. "Identification des sources de vibration en usinage étude expérimentale et numérique /." [S.l.] : [s.n.], 2006. ftp://ftp.scd.univ-metz.fr/pub/Theses/2006/Castro_Martinez.Luis_Ricardo.SMZ0624.pdf.
Njeh, Mohamed. "Contribution au contrôle des pulsations de couple d'une propulsion hybride." Poitiers, 2011. http://nuxeo.edel.univ-poitiers.fr/nuxeo/site/esupversions/df030f33-74b2-48ca-a265-d7a9aaebe169.
The research presented in this PhD thesis concerns the development of new control strategies to attenuate the insanteneous torque ripples of a hybrid diesel/electric propulsion. On a diesel engine, torque ripples are quasiperiodic for a given rotational speed. We present two strategies to control fixed and variable speed to reduce torque ripples. In the first approach, the state model is expressed in a rotating frame at the frequency of the harmonic rejection. This particular model leads to consider a harmonic ripple as a exogenous constant signal. This control strategy is based on a dynamic output feedback synthesis. The second approach is based on internal model control. The controller has a copy of the exogenous disturbance of the model. This is a problem of persistent disturbance rejection and reference tracking. We will adapt these approaches for control of variable speeds. In this case, the system models and controllers are with varying parameters (Linear Parameter Varying). We present a synthesis method based on S-procedure and full-block multipliers to solve the problem of output feedback. These strategies are applied to an experimental benchmark consists of mono-cylinder diesel engine coupled to a permanent magnets synchronous machine
Chibane, Hicham. "Contribution à l'optimisation multi-objectif des paramètres de coupe en usinage et apport de l 'analyse vibratoire : application aux matériaux métalliques et composites." Thesis, Tours, 2013. http://www.theses.fr/2013TOUR4053/document.
Manufacturing processes of mechanical parts by removal of material (turning, milling, drilling ...) have extensive use in aeronautic and automobile industry. The components obtained using these methods must satisfy geometric properties, metallurgical and quality characteristics. To meet these requirements, several experimental tests based on the selection of cutting conditions are often necessary before manufacturing. Currently, these empirical methods based on the experience of manufacturers and users of cutting tools (charts, diagrams with experimental findings, ...) are often very lengthy and costly. However, the high cost of a trial limits the number of experiments, so to have a deserted component with an acceptable cost is a difficult task. The importance of cutting conditions monitored by limitations is related to the type of material to be machined, since it determines the behavior of the machining
Azam, Sufyan. "Electrical Properties and Surface Characterization of Thin Copper Films Subjected to Mechanical Vibrations." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/670604.
Se estudiaron las características mecánicas y eléctricas de películas delgadas de cobre adheridas a laminados epoxi FR4, bajo carga térmica y mecánica. En la 1ª etapa se determinaron de forma experimental y analítica los parámetros modales como las frecuencias naturales y los ratios de amortiguamiento utilizando un método de elementos finitos para cuatro grupos de muestras, con el fin de estudiar los efectos geométricos y la presencia de un agujero central de diferentes diámetros. Se ha descubierto que estos tamaños son adecuados para su uso como placas de circuitos electrónicos que sufren cambios de frecuencia significativos que van desde 40 Hz a 1 kHz. Se encontró que la frecuencia de resonancia fundamental de todas las muestras era inferior a 40 Hz y la influencia de un orificio central no fue significativa para afectar las propiedades modales. Durante la segunda etapa de la investigación realizada, se determinó el efecto de las vibraciones de alta frecuencia sobre las propiedades eléctricas. Se encontró experimentalmente que las tensiones inducidas en las películas delgadas debido a la alta frecuencia y al número de ciclos afectan significativamente la resistencia de la hoja del material y otras propiedades eléctricas como la resistividad y la conductividad. Estas cargas mecánicas finalmente reducen el rendimiento eléctrico de las películas delgadas de cobre (PCB). Las imágenes SEM mostraron la formación de grietas cerca de la zona de alta tensión; estas fisuras propagan posteriormente la avería del equipo. El cambio de temperatura de la superficie de 25ºC a 45ºC mostró un pequeño cambio en la resistencia laminar de las películas delgadas de cobre. Por lo tanto, esta tesis ha sido una contribución a una mejor comprensión de la relación entre la acumulación de daños y el rendimiento eléctrico de las placas de PCB y MEMS y puede conducir a mejoras en su fabricación. Esto hace que los resultados sean de gran importancia práctica y la metodología de ensayo desarrollada se puede extender a otras películas delgadas.
Mechanical and electrical characteristics of thin copper films bonded to FR4 epoxy laminates, under thermal and mechanical loading, were studied. At the 1st stage modal parameters such as Natural frequencies and damping ratios were determined experimentally and analytically using a finite element method for four groups of samples, in order to study the geometric effects and the presence of a central hole of different diameters. It has been found that these sizes are suitable to be used as electronic circuit boards that undergo significant frequency changes ranging from 40 Hz to 1 kHz. The fundamental resonance frequency of all the specimens was found to be less than 40 Hz and the influence of a central hole was not significant to affect the modal properties. During the second stage of the accomplished research, the effect of high frequency vibrations on the electrical properties were determined. It was found experimentally that the stresses induced in the thin films due to high frequency and number of cycles significantly affect material sheet resistance and other electrical properties such as resistivity and conductivity. These mechanical loadings ultimately reduces electrical performance of thin copper films (PCBs). SEM images showed formation of cracks near the high stress zone; these cracks later propagates the failure of the equipment. The surface temperature change from 25ºC to 45ºC showed a little change in sheet resistance of thin copper films. This thesis has thus been a contribution to a better understanding of the relationship between damage accumulation and electrical performance of PCB boards and MEMS and may lead to improvements of their fabrication. This makes the results of great practical importance and the developed assay methodology can be extended to other thin films.
Wu, Hailong. "Modelization and control of synchronous reluctance machines for the torque ripple minimization - study of vibrational and acoustic behavior." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCA003.
This thesis aims to study the control and optimization of a synchronous reluctance machine for the purpose of improving the vibrational performance. The main works of the thesis can be classified into three parts: the proposed torque ripple reduction method, the factors which can influence the proposed method and the influence of the proposed method.At first, the torque ripple of synchronous reluctance machine is reduced by a control method. Firstly, a torque equation is proposed in order to present the relationship between torque ripple and the optimal currents. Then a new parameter, torque function, is put forward. Based on the torque function, the torque ripple reduction strategy is presented. Two different torque ripple minimizations are proposed by applying different torque function harmonics. They are analyzed and compared in order to define the optimal method. In order to test the proposed method further, the selected torque ripple minimization approach is applied to three SynRMs. The results of finite element simulations imply that the proposed method is effective to decrease the torque ripples of these three SynRMs. The proposed torque ripple reduction method is verified according to the models built in MATLAB/Simulink and the experiment results respectively.Then the factors which could influence the proposed torque ripple reduction method are analyzed. Firstly, torque function is a function of rotor position, current angle and saturation. Based on the model in Simulink, the influence of different starting position on the performance of the studied SynSR is analyzed. Besides, the estimated position errors produced by senserless control could also affect the toque ripple minimization by changing torque function. At last, the influence of saturation on the proposed torque ripple reduction method is introduced because the amplitudes of the optimal currents are increased.In addition, the influence of torque ripple reduction on the other perfomances of SynRM is analyzed. The optimal currents have more harmonics than the original sinusoidal currents. So three losses (copper losses, iron losses and inverter losses) are modeled, calculated, analyzed and compared. According to the results, the copper losses are the most sensible losses. The iron losses and the inverter losses are a little increased and the increased parts can be neglected. Besides, reducing torque ripple by adding stator currents could influence the vibro-acoustic of the studied SynRM. Thus this section aims to explain the relationship between torque ripple reduction and acoustic noise. An analytical equation is proposed in order to evaluate the variation of noise produced by torque ripple reduction. Simulations in Flux 2D have been performed in order to calculate the variation of noise resulted by torque ripple reduction. At last, the software Manatee which is professional in studying the vibration and noise is applied for the purpose of comparing the results with those of the finite element analysis
Yang, Kang. "Numerical and semi analytical models for electromagnetic ring expansion test." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2350.
High stain rate material deformations are prevalent during high speed impacts, high speed forming/welding, cutting, crimping, blast etc. Characteristics of materials under high strain rate deformation do not follow the same as it occurs under the quasi-static loading conditions. However, characterization of materials under high strain rate deformation is always challenging and it requires sophisticated equipment. Thanks to the development in electromagnetic forming technology, the electromagnetic ring expansion test shows a great potential to be used to characterize materials under high strain rate conditions. During the electromagnetic ring expansion test, the workpiece can reach deformation velocities in the order of 100 m/s and a strain rate of up to 104 s-1. Consequently, this test can be used to predict the material parameters such as the strain rate hardening and ductility under extremely high strain rates (strain rates in the order of 103 – 104 s-1). In order to achieve this goal, an appropriate model is required to describe the process. The model should contain an electromagnetic-mechanical-thermal coupling to obtain the accurate multi-physics nature of the problem. There exist two main modeling methods in literature, viz., the semi-analytical methods and finite element methods (sometime combined with boundary element method). Normally, the semi-analytical methods require short calculation time while it provides lower accuracy in comparison with finite element methods. However, due to the complexity of multi-physics coupling, the calculation error is difficult to be analyzed. Moreover, errors in calculation and identification assumptions may also result from heterogeneous deformations or localized specific phenomena (such as local necking at multi points or electric current localization, skin effect, edge effect of Lorentz force etc.) that could influence identification work as well as stress and strain states. Therefore, this thesis mainly focused on the analysis and modeling methods of ring expansion test including local behaviors and dynamic phenomena with the help of experimental and numerical tools. Moreover, this thesis also includes a development of a semi-analytical method with multi-physics coupling capabilities, which has been validated using a theoretical model and experimental frameworks. Experimental measurements were obtained using high-speed cameras and photonic Doppler velocimetry (PDV) for various test cases are used together with numerical models to investigate the process and material parameters. The models used to analyze the stress and stain states during a ring expansion test show that the ring expansion test is not a pure uniaxial tensile test as claimed by researchers. Besides, another potential process behavior, the vibration phenomena that occurs during the elastic recovery was investigated using multi-physics simulations and PDV systems. This investigation of the elastic recovery helps to understand the potential influencing parameters of the test those are applicable and could be used to control the springback phenomenon during other electromagnetic forming processes. The semi-analytical modeling method for ring expansion test including four calculation parts (mechanical part, eddy current, Lorentz force calculation, thermal part) were analyzed with the help of numerical simulations. The results obtained from analytical work closely resemble with the numerical simulations for both theoretical model and an experimental case study. The error analysis of various physical aspects allows improving the accuracy of semi-analytical calculation that could be used as an additional platform to obtain rapid calculation of the test conditions. This semi-analytical method could be extended in the future to identify material parameters under high strain rate deformations
Belhadi, M'hamed. "Étude de machines à réluctance variable pour une application de traction électrique : réduction des ondulations de couple et des efforts radiaux." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112185.
This report deals with switched reluctance motor by offering design solutions to the drawbacks of torque ripples and radial forces in the same time. Torque ripples reduce the user comfort and radial forces are the origin of noise. In the first part, an axial structure characterized by low radial force is analysed. Indeed, an axial configuration with two stators and one rotor is the most appropriate to replace the reference radial machine. Ones the rules of passage from one structure to another are established, the axial structure is then compared to the reference one. A first passage is made by keeping the same volume and a second one by sizing the axial machine with the same specifications as the radial one. In the second part, the work concerns the modification of radial structure of the reference machine and its optimization. Several modifications are proposed including a structure with a magnetic wedge which is the most efficient. Geometric optimization using genetic algorithm are then performed on operating points to remedy the both problems. In the end, several optimized structures are proposed. The choice of the most suitable machine can be done by making a compromise between the torque maximization, reducing its ripples and reducing radial forces
Fairhurst, Charles. "Contribution a l'amelioration de l'abattage mecanique de roches agressives : le pic assiste et le pic vibrant." Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0111.
Mejri, Seifeddine. "Identification et modélisation du comportement dynamique des robots d'usinage." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22688/document.
Machining robots have major advantages over cartesian machine tools because of their flexibility, their ability to reach inaccessible areas on a complex part, and their important workspace. However, their lack of rigidity and precision is still a limit for precision tasks. The stresses generated by the cutting forces and inertia are important and cause static and dynamic deformations of the structure which result in problems of workpiece surface. The aim of the thesis work is to characterize the dynamic behavior of robots during machining operation. This work followed a three-step approach : Modeling a first model considered as a reference where the robot is at rest. Then the identification of the dynamic behavior in service. Finally, the prediction of the cutting stability using the robot dynamic model. The originality of this work is the development of new operational modal identification methods. They integrate the machining conditions and result into a more accurate model than the first model of reference without being biased by harmonics. Finally, guidlines of robot’s configurations and excitation forces’ direction are proposed to ensure the robotic machining stability
Nguyen, Duy-Minh. "Commande intermittente de la machine à réluctance variable à double saillance." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS197/document.
The intermittent control aims to increase the efficiency of the machine-converter system by reducing the losses. In the purpose to maintain the average torque of the machine required by the load, this control increases the reference torque and turns off some phases during each electrical period or each mechanical period. By this fact, it reduces the converter losses and the ferromagnetic losses of the machine. It also has a freedom in the selection of the activated phases which influences the generated frequencies of the current, the radial force and the torque. Therefore, this strategy of the intermittent control, which is called sliding strategy, can avoid the excitation of the natural frequencies of the stator, or those of the drivetrain. It aims to reduce the negative effects of the intermittent control vis-à-vis the vibration of the stator and the pulsation of the drivetrain which are respectively at the origins of acoustic noise and mechanical jerks. Finally, the intermittent control is validated on driving cycles and can save up to 5.17 % of the consumed electrical energy
Rognon, Hervé. "Comportement en fatique sous environnement vibratoire : prise en compe de la plasticite au sein des methodes spectrales." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00864892.
Gadari, M’hammed El. "Étude expérimentale et numérique du comportement des joints à lèvre." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2304/document.
It's about sixty years that we are interested in understanding and modeling the Elastohydrodynamic behavior (EHD) of rotary lip seals. However, we can consider that, until now, their modeling has not been accurately treated. Even though many studies have been devoted to this model, several questions have been raised and are still the subject of controversy among researchers, namely the parameters influencing on the rotary lip seals performance, such as: the shaft surface textured, the law adopted for the mechanical behavior of lip seals, the approach used to develop the matrix of compliance, the importance of assuming the smooth or rough shaft, and finally the ratio between the width of contact and the wavelength according the circumferential direction of the lip roughness.The main goal of this thesis is to answer rigorously these questions by developing and validating a numerical tool for EHD rotary lip seals modeling, that takes into account: the lip law behavior, the compliance matrix rigorously validated by assuming smooth shaft case, or rough and textured shaft case. In addition, an analytical approach is proposed, models the vibratory behavior of the "squeeze film". This implies a nonlinear comportment that is taken into account
Bel, Mabrouk Imen. "Etude des effets des charges aérodynamiques sur le comportement dynamique non linéaire des éoliennes à axe vertical." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMIR17.
This thesis focuses on the study of the aerodynamic loads effects on the nonlinear dynamic behavior of Darrieus--type vertical axis wind turbine. The latter has received more attention due to its efficiency in urban regions compared to other wind turbines. In fact, the wind flow speed in urban regions continuously changes direction and is extremely turbulent. The inherent characteristics of its omni-directionality make it more suitable to harnessing this kind of flow. It is known that Darrieus wind turbine is characterized by an inherently unsteady aerodynamic behavior and a complex flow around rotor blades. The non-stationary behavior of the mentioned turbine increases vibration. These aerodynamic vibrations are transmitted to the gearing mechanism. We have, firstly, developed a numerical simulation, allowing to simulate the complexity of the unsteady aerodynamic phenomena keeping a compromise between the reliability of prediction and the rapidity of calculation. This numerical simulation has been carried out using a two-dimensional unsteady Computational Fluid Dynamics (CFD) method. Simulation results compared to those available in the literature are in good agreement. The Darrieus turbine efficiency is also optimized; thus introducing a significant scientific contribution. The latter is the objective of analyzing the aerodynamic load impact in the dynamic behavior of the Darrieus turbine in non-stationary regime. In this context, a parametric study has been developed in order to find optimal functioning of the studied turbine, which is characterized by the most performing aerodynamic torque associated with acceptable levels of dynamic vibration. In general, it is difficult to predict the dynamic response of the wind turbine with a good level of accuracy due to the aerodynamic loads turbulence and uncertain characteristics. It becomes necessary to take into account the uncertainty in the input parameters to ensure the robustness of the Darrieus turbine geared system. In a robustness study objective, the Polynomial Chaos method is adopted to predict the nonlinear dynamic behavior of the gearing system taking into account uncertainties which are associated to the performance coefficient of the input aerodynamic torque. This leads to an important scientific research contribution. The results have shown a large dispersion of the random parameter in the dynamic response of the gearing system compared to the deterministic study. That proves the insufficiency of that study for a robustness analyses. They have also proved that the Polynomial Chaos method is an efficient probabilistic tool for uncertainty propagation. Finally, the new proposed robust mechanical analysis indicates a good capacity to investigate the dynamic behavior of the Darrieus turbine thanks to its superior predictive capabilities in coupling complex aerodynamic phenomena with a mechanical gearing system vibration. Where the originality of such correlation in our work
Cebrecos, Ruiz Alejandro. "Transmission, reflection and absorption in Sonic and Phononic Crystals." Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/56463.
[ES] Los cristales fonónicos son materiales artificiales formados por una disposición periódica de inclusiones en un medio, pudiendo ambos ser de carácter sólido o fluido. Controlando la geometría y el contraste de impedancias entre los materiales constituyentes se pueden controlar las propiedades dispersivas de las ondas. Cuando una onda propagante se encuentra un medio con diferentes propiedades físicas puede ser transmitida y reflejada, en medios sin pérdidas, pero también absorbida, si la disipación es tenida en cuenta. La presente tesis está dedicada al estudio de diferentes efectos presentes en cristales sónicos y fonónicos relacionados con la transmisión, reflexión y absorción de ondas, así como el desarrollo de una técnica para la caracterización de sus propiedades dispersivas, descritas por la estructura de bandas. En primer lugar, se estudia el control de la propagación de ondas en transmisión en sistemas conservativos. Específicamente, nuestro interés se centra en mostrar cómo los cristales sónicos son capaces de modificar la dispersión espacial de las ondas propagantes, dando lugar al control del ensanchamiento de haces de sonido. Haciendo uso de las curvas de dispersión espacial extraídas del análisis de la estructura de bandas, se predice primero la difracción nula y negativa de ondas a frecuencias cercanas al borde de la banda, resultando en la colimación y focalización de haces acústicos en el interior y detrás de un cristal sónico 3D, y posteriormente se demuestra mediante medidas experimentales. La eficiencia de focalización de un cristal sónico 3D está limitada debido a las múltiples reflexiones existentes en el interior del cristal. Para superar esta limitación se consideran estructuras axisimétricas trabajando en el régimen de longitud de onda larga, como lentes de gradiente de índice. En este régimen, las reflexiones internas se reducen fuertemente y, en configuración axisimétrica, la adaptación de simetría con fuentes acústicas radiando haces de sonido incrementa la eficiencia drásticamente. Además, la teoría de homogenización puede ser empleada para modelar la estructura como un medio efectivo con propiedades físicas efectivas, permitiendo el estudio del frente de ondas en términos refractivos. Se mostrará el modelado, diseño y caracterización de un dispositivo de focalización eficiente basado en los conceptos anteriores. Considérese ahora una estructura periódica en la que uno de los parámetros de la red, sea el paso de red o el factor de llenado, cambia gradualmente a lo largo de la dirección de propagación. Los cristales chirp representan este concepto y son empleados aquí para demostrar un mecanismo novedoso de incremento de la intensidad de la onda sonora basado en un fenómeno conocido como reflexión "suave". Este incremento está relacionado con una ralentización progresiva de la onda conforme se propaga a través del material, asociado con la velocidad de grupo de la relación de dispersión local en los planos del cristal. Un modelo basado en la teoría de modos acoplados es propuesto para predecir e interpretar este efecto. Se observan dos fenómenos diferentes al considerar pérdidas en estructuras periódicas. Por un lado, si se considera la propagación de ondas sonoras en un array periódico de capas absorbentes, cuyo frente de ondas es paralelo a los planos del cristal, se produce una reducción anómala en la absorción combinada con un incremento simultáneo de la reflexión y transmisión a las frecuencias de Bragg, de forma contraria a la habitual reducción de la transmisión, característica de sistemas periódicos conservativos a estas frecuencias. En el caso de la misma estructura laminada en la que se cubre uno de sus lados mediante un reflector rígido, la incidencia de ondas sonoras desde un medio homogéneo, cuyo frente de ondas es perpendicular a los planos del cristal, produce un gran incremento de la fuerza de
[CAT] Els cristalls fonònics són materials artificials formats per una disposició d'inclusions en un medi, ambdós poden ser sòlids o fluids. Controlant la geometría i el contrast d'impedàncies dels seus materials constituents, és poden controlar les propietats dispersives de les ondes, permetent una gran varietatde fenòmens fonamentals interessants en el context de la propagació d'ones. Quan una ona propagant troba un medi amb pèrdues amb propietats físiques diferents es pot transmetre i reflectir, però també absorbida si la dissipació es té en compte. Aquests fenòmens fonamentals s'han explicat clàssicament en el context de medis homogenis, però també ha sigut un tema de creixent interés en el context d'estructures periòdiques en els últims anys. Aquesta tesi doctoral tracta de l'estudi de diferents efectes en cristalls fonònics i sònics lligats a la transmissió, reflexió i absorció d'ones, així com del desenvolupament d'una tècnica de caracterització de les propietats dispersives, descrites mitjançant la estructura de bandes. En primer lloc, s'estudia el control de la propagació ondulatori en transmissió en sistemes conservatius. Més específicament, el nostre interés és mostrar com els cristalls sonors poden modificar la dispersió espacial d'ones propagants donant lloc al control de l'amplària per difracció dels feixos sonors. Mitjançant les corbes dispersió espacial obtingudes de l'anàlisi de l'estructura de bandes, es prediu, en primer lloc, la difracció d'ones zero i negativa a freqüències próximes al final de banda. El resultat és la collimació i focalització de feixos sonors dins i darrere de cristalls de so. Després es mostra amb mesures experimentals. L'eficiència de focalització d'un cristall de so 3D està limitada per la gran dispersió d'ones dins del cristall, que és característic del règim difractiu. Per a superar aquesta limitació, estructures axisimètriques que treballen en el règim de llargues longituds d'ona, i es comporten com a lents de gradient d'índex. En aquest règim, la dispersió es redueix enormement i, en una configuració axisimètrica, a causa de l'acoblament de la simetría amb les fonts acústiques que radien feixos sonors, l'eficiència de radiació s'incrementa significativament. D'altra banda, la teoria d'homogeneïtzació es pot utilitzar per a modelar, dissenyar i caracteritzar un dispositiu eficient de focalització basat en aquests conceptes. Considerem ara una estructura periòdica en la qual un dels seus paràmetres de xarxa, com ara la constant de xarxa o el factor d'ompliment canvia gradualment al llarg de la direcció de propagació. Els cristalls chirped representen aquest concepte i s'utilitzen ací per a demostrar un mecanisme nou d'intensificació d'ones sonores basat en el fenòmen conegut com a reflexió "suau". La intensificació està relacionada amb la alentiment progressiva de l'ona conforme propaga al llarg del material, que està associada amb la velocitat de grup de la relació de dispersió local en els diferents plànols del cristall. Es proposa un model basat en la teoria de modes acoblats per a predir i interpretar este efecte. Dos fenòmens diferents cal destacar quan es tracta d'estructures periòdiques amb dissipació. Per un costat, al considerar la propagació d'ones sonores en el plànol en un array periòdic de capes absorbents, s'observa una disminució anòmala de l'absorció i es combina amb un augment simultani de reflexió i transmissió en les freqüències de Bragg que contrasta amb la usual disminució de transmissió, característica dels sistemes conservatius a eixes freqüències. Per a un medi similar de capes, amb un reflector rígid darrere, les ones fora del pla incidint l'estructura des de un medi homogeni, augmentaran considerablement la interacció. En altres paraules, el retràs temporal de les ones sonores dins del sistema periòdic augmentarà significativament produint un augmen
Cebrecos Ruiz, A. (2015). Transmission, reflection and absorption in Sonic and Phononic Crystals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/56463
TESIS
Premiado
Moreau, Vincent. "Etude dynamique de l'usinage et de l'interaction pièce-outil par mesure des déplacements : application au fraisage et au tournage." Phd thesis, 2010. http://pastel.archives-ouvertes.fr/pastel-00005924.
Jhuang, Kai-Lin, and 莊凱麟. "Theoretical Analysis of Free Vibrations on Two Piezoelectric Plates Couple with Bounded Fluids." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/07488560423902119488.
國立臺灣科技大學
機械工程系
104
This study investigated the vibration characteristics of two piezoelectric plates coupled with bounded compressible inviscid fluid by theoretical analysis. The Rayleigh–Ritz method and the coupled equation of hydrostatic equilibrium were developed to study two kinds of Fluid-Structure Interaction (FSI) system. The first FSI system in this study is two piezoelectric circular plates placed on the top and the bottom of a cylindrical container, respectively. The governing equation of piezoelectric circular plate is obtained by using the constitutive equations of piezoelectric plate and the equilibrium of mechanic. The governing equation of fluid is obtained from acoustic wave equation. The FSI between the piezoelectric plate and bounded fluid are obtained by employing the integral transformation technique. The frequency eigenfuction of the FSI system can be derived by the Rayleigh–Ritz method. Finally, the dynamic characteristic of the FSI system, including resonant frequencies, corresponding mode shapes, and pressure field of the fluid can be obtained from theoretical solution. The second FSI system in this study is two piezoelectric retangular cantilever plates immersed in the wall of rectangular container which is symmetric to the middle plane of container. The vibration displacement of piezoelectric retangular cantilever plate is obtained by the governing equation of piezoelectric plate and the superposition method. The governing equation of fluid is obtained from acoustic wave equation. The FSI between the piezoelectric plate and fluid are obtained by employing the integral transformation technique. The frequency eigenfuction of the FSI system can be derived by the coupled equation of hydrostatic equilibrium. Resonant frequencies, corresponding mode shapes, and pressure field of the fluid can be obtained by solving the characteristics equation.The vibration characteristics of theoretical analysis are verified with the results from finite element method(FEM). Furthermore, the theoretical solution was used to discuss the effects of the compressibility, density, depth of fluid on the resonant frequency.
Yaqub, Sajid. "Proposition d'une démarche pour identifier les efforts de coupe en présence de talonnage." Phd thesis, 2011. http://pastel.archives-ouvertes.fr/pastel-00552052.
Moraru, George-Florin. "Etude du comportement du système "Pièce-Outil-Machine" en régime de coupe vibratoire." Phd thesis, 2002. http://tel.archives-ouvertes.fr/tel-00005711.
Guibert, Nicolas. "Etude et modélisation de l'influence des phénomènes de coupe sur les performances du forage vibratoire." Phd thesis, 2008. http://tel.archives-ouvertes.fr/tel-00360827.
Rouleau, Alexandre. "Évaluation de stratégies visant la réduction des contraintes physiques pour les membres supérieurs associées au boulonnage à la clé à chocs pneumatique sur le plan horizontal et vertical dans les secteurs des services à l'automobile." Mémoire, 2010. http://www.archipel.uqam.ca/2746/1/M11313.pdf.