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電磁共振ダンパによる振動制御井上, 剛志, INOUE, Tsuyoshi, 石田, 幸男, ISHIDA, Yukio, 角, 正貴, SUMI, Masaki 09 1900 (has links)
No description available.
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Simulační analýza vibrací turbodmychadla / Simulation anlysis of turbocharger vibrationsValo, Lukáš January 2019 (has links)
The master thesis deals with computational modeling of a turbocharger vibrations and and assessment of influnce of passive dynamic vibration absorber on vibrations of actuator bracket. The use of dynamic vibration absorber was summarized in the research study. The analysis were performed using finite element method in ANSYS. Several computational models of turbocharger were created with different ways of modeling bolted joints between turbocharger parts. Modal analysis of each model was performed and the results were compared. For the selected model, the response to the kinematic excitation from the internal combustion engine for two load conditions was calculated using harmonic analysis. A simple model of vibration dynamic absorber was applied to the turbocharger model with reduced degrees of freedom and its influnce on vibrations of actuator bracket was investigated. Significant decrease of the maximum acceleration amplitude was achieved in a given frequency range when absorber parameters were optimized.
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A dual reaction-mass dynamic vibration absorber for active vibration controlHeilmann, John 18 September 2008 (has links)
Traditional dynamic vibration absorbers (DVAs) consist of a mass-spring-damper system and are an effective means of attenuating structural vibration over a narrow frequency band. The effective bandwidth of the DVA can be increased by the addition of an externally controlled force, generally applied between the reaction-mass and the primary structure. Such devices are known as hybrid DVAs. This thesis presents a new hybrid DVA configuration which utilizes two reaction-masses in parallel. On this proposed hybrid dual-mass (DM) DVA, the control force is applied between the reaction-masses. It is shown that in broadband control applications, the proposed DM-DVA requires less control force to achieve the same primary attenuation as the traditional hybrid single-mass (SM) DVA. The hybrid DM-DVA was compared to the hybrid SM-DVA with two tests. A numerical simulation of the hybrid DVAs attenuating a single-degree-of-freedom structure was performed. To achieve an equal amount of primary attenuation, the hybrid SM-DVA required 65% higher root-mean-square (RMS) control effort than the hybrid DV-DVA. The numerical model also demonstrated that the hybrid DM-DVA was less sensitive to changes in the system as compared to the hybrid SM-DVA. Additionally, a prototype hybrid DVA was built which could be configured as either the hybrid SM or DM-DVA. The prototype hybrid DVA was used with the feedforward Filtered-X LMS algorithm to control the vibration of a fixed-free beam. The hybrid SM and DM-DVAs attenuated the primary response by a factor of 11.5 and 12.3, while requiring control efforts of 4.9 and 2.7 V/N RMS, respectively. Thus, the hybrid DM-DVA required 45% less control effort while yielding a higher attenuation ratio in this experiment. These results demonstrate the superior performance of the proposed DM-DVA for broadband control applications as compared to the traditional SM-DVA. / Master of Science
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Projeto, análise e otimização de um absorvedor dinâmico de vibrações não linear / Design, analysis and optmization of a nonlinear dynamic vibration absorberGodoy, Willians Roberto Alves de 22 February 2017 (has links)
Absorvedores de vibração são comumente usados em aplicações com intuito de reduzir indesejadas amplitudes de vibração de estruturas e maquinas vibrantes. O conceito de um absorvedor de vibração linear consiste na ideia de projetar um subsistema com frequência de ressonância coincidente com uma dada frequência de interesse, tal que a amplitude de vibração do sistema primário e significativamente reduzida quando comparada a situação original, sem o absorvedor de vibração. Porem, uma deficiência dos absorvedores de vibração lineares típicos e sua estreita faixa de frequência de operação. Para superar essa deficiência, muitas tentativas de solução usando subsistemas não lineares tem sido propostas na literatura, ja que se apropriadamente projetados, eles podem aumentar a faixa de frequência de absorção de vibração e/ou melhorar a redução das amplitudes de vibração do sistema primário. Contudo, a síntese e o projeto de tais absorvedores não lineares não e tão simples e direta como no caso linear. Baseado na geometria de uma topologia proposta e encontrada na literatura, que compreende a inclusão de uma montagem do tipo snap through truss no lugar da mola linear do absorvedor de vibração, este trabalho tem intenção de apresentar um estudo sobre o projeto e otimização de um absorvedor dinâmico de vibrações não linear. Portanto, o efeito dos parâmetros do absorvedor e analisado quanto as perspectivas de redução das amplitudes de vibração do sistema principal como também de aumento da faixa de frequência de operação. A analise paramétrica do absorvedor foi promovida para responder questões sobre as variáveis de projeto, tanto físicas como geométricas. Realizou-se otimização do absorvedor com objetivo de sintoniza-lo a frequência de trabalho desejada, através de busca extensiva e algoritmos genéticos. Os resultados mostram que o absorvedor não linear proposto pode ser mais efetivo que seu correspondente linear em ambos os aspectos, na redução da máxima amplitude de vibração e no aumento da faixa de frequência de absorção. Portanto, apesar da dificuldade inicial de projeto, esse tipo de absorvedor representa uma alternativa interessante na atenuação das amplitudes de vibração ao longo de uma extensa faixa de frequência. / Dynamic vibration absorbers are commonly used in several applications in order to reduce undesired vibration amplitudes of vibrating machinery and structures. The concept of a linear vibration absorber is based on the idea of designing a subsystem with a resonance frequency coincident with a given frequency of interest such that the vibration amplitude of the primary system is significantly reduced when compared to the original situation (without the vibration absorber). But one of the known handicaps of typical linear vibration absorbers is their narrow frequency range of operation. To overcome this handicap, a number of tentative solutions have been proposed in the literature using nonlinear subsystems. If properly designed, they could enlarge the frequency range of vibration absorption and/or improve vibration reduction of the primary system. However, the synthesis and design of such nonlinear absorbers are not as straightforward as for their linear counterpart. A proposed design found in the open literature consists of replacing the linear spring of the vibration absorber by a nonlinear snap-through truss. This work aims to present a study on the design and optimization of a nonlinear dynamic vibration absorber based on snap-through absorber geometry. The effect of the absorber parameters was analyzed on both, the primary system vibration amplitude reduction and the frequency range of operation. Parametric analyses of the absorber were carried out to answer questions about the physical and geometric design variables. The absorber optimization was performed in two different ways, by extensive search and genetic algorithms, in order to tune it in the desired working frequency. The results show that the proposed nonlinear vibration absorber may be more effective than its linear counterpart both in terms of maximum vibration amplitude reduction and absorption frequency-range. Therefore, despite the increased design complexities such an absorber is an interesting alterna- tive in attenuating vibration amplitudes over a wide frequency range.
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Wave energy capture system ¡V surge motion tankHuang, Kuang-Li 17 February 2011 (has links)
Liquid sloshing in a 2D tank applied on a wave energy capture system and reducing the oscillation of an offshore platform are discussed in this study. A fully nonlinear time-independent finite difference method and the forth-order Runge-Kutta method are implemented to solve the coupled motions of liquid sloshing in a 2D tank with a floating platform. When the external forcing frequency of the Dynamic Vibration Absorber System composed by a tuned liquid damper and a tuned mass damper is identical to the fundamental frequency of the tank, the external force can be effectively diminished by the sloshing-induced force. In the meantime, the maximum effect of tuned mass damper on reducing the amplitude of the floating platform appears. When the frequency of external forcing is close to the first natural frequency of the liquid tank, the coupled effect between the motions of both the tank and the platform can effectively reduce the vibration of the platform and the total energy of the whole system. The Eigenfrequency of a wave capture system is formed by the coupled effect of a liquid tank and a wave capture system. When the excitation frequency of the wave capture system is near its Eigenfrequency, the sloshing-induced force is much larger than that of external and the maximum displacement of the wave energy capture system occurs. As a result, the wave energy capacity of the wave capture system can be averagely increased to 150% by the influence of liquid sloshing in the tank.
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Absorvedor dinâmico de vibração tipo lâmina vibrante / Vibrating blade dynamic vibration absorberKotinda, Giovanni Iamin 08 July 2005 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work is dedicated to the design of a vibrating blade dynamic vibration absorber
(ADVLV), which is composed by a blade that is subjected to an initial traction T , and contains
a concentrated mass m that is fixed at a given position d along the blade. These three
parameters can be adjusted so that the ADVLV is tuned. For this aim, a finite element model of
the system was built, leading to a design methodology for the absorber. Also, design of
experiment techniques were performed to obtain the most interesting configurations for the
system, both for the computational and experimental models. Special care was taken with
respect to the boundary conditions for the finite element model, so that the dynamic responses
could correspond to the physical aspects of the problem, accordingly. Besides, an experimental
prototype was constructed and tested under laboratory conditions. The experimental results
were compared with those obtained from mathematical simulation. From this comparison, it was
concluded that the finite element model had to be updated in such a way that experimental
results could match. A vibrating string dynamic vibration absorber (ADVCV) was also studied.
However, this DVA configuration presented two anti-resonant frequencies due to the coupling of
the first vibration mode along the horizontal and vertical directions with a concentrated mass.
Another phenomenon that was observed is the tridimensional motion of the vibrating string
around its equilibrium position, leading to an ellipsoid-shape movement when a harmonic
excitation whose frequency coincides with the primary system resonance frequency is applied to
the system. This way, the ADVCV is not able to attenuate the vibration amplitude of the primary
system satisfactorily. It is worth mentioning that the proposed ADVLV presents a good dynamic
behavior besides a wide frequency range along which the DVA can be tuned. Besides, the
present vibration absorbing device is simple and can be easily connected to the primary system
both to mechanical and civil engineering structures. / Este trabalho aborda o projeto de um absorvedor dinâmico de vibrações do tipo lâmina
vibrante (ADVLV), sendo este constituído por uma lâmina sujeita a uma tração inicial T com
uma massa concentrada m que pode ser fixada em uma posição d da lâmina. Este três
parâmetros podem ser alterados a fim de se obter a sintonia do ADVLV. Para realizar o estudo
deste, foi elaborado um modelo de elementos finitos do sistema, permitindo assim obter a
metodologia para seu projeto. Também foram usadas técnicas de planejamento de
experimento para obter as melhores configurações, tanto para os ensaios computacionais
como experimentais. Foram tomados cuidados na criação das condições de contorno do
modelo de elementos finitos, a fim de se obter respostas que representem adequadamente os
aspectos físicos do problema. Também foi construído um protótipo e este foi ensaiado no
laboratório. Os resultados obtidos foram comparados com os obtidos através da simulação
computacional. A partir desta comparação verificou-se a importância de realizar ajustes no
modelo de elementos finitos para adequar este à realidade. Também foi estudado o absorvedor
dinâmico de vibração do tipo corda vibrante. Entretanto este ultimo ADV apresentou duas
freqüências de anti-ressonância devido ao acoplamento do primeiro modo de vibrar nas
direções horizontal e vertical da corda vibrante com uma massa concentrada. Outro fenômeno
observado foi o movimento tridimensional da corda vibrante em torno da sua posição de
equilíbrio, resultando uma forma semelhante a um elipsóide de revolução quando uma
excitação harmônica com freqüência igual à freqüência de ressonância do sistema primário é
aplicada sobre o sistema. Desta forma, o ADVCV não consegue cumprir a sua função de
atenuar a amplitude de vibração da estrutura primária, sendo, portanto, completamente
ineficiente neste caso. O ADVLV, proposto neste trabalho, apresentou comportamento
dinâmico satisfatório, além de uma grande faixa de freqüências na qual o ADV pode ser
sintonizado. Este dispositivo é de fácil construção e acoplamento, tanto a sistemas mecânicos,
como a estruturas de construção civil. / Mestre em Engenharia Mecânica
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Projeto, análise e otimização de um absorvedor dinâmico de vibrações não linear / Design, analysis and optmization of a nonlinear dynamic vibration absorberWillians Roberto Alves de Godoy 22 February 2017 (has links)
Absorvedores de vibração são comumente usados em aplicações com intuito de reduzir indesejadas amplitudes de vibração de estruturas e maquinas vibrantes. O conceito de um absorvedor de vibração linear consiste na ideia de projetar um subsistema com frequência de ressonância coincidente com uma dada frequência de interesse, tal que a amplitude de vibração do sistema primário e significativamente reduzida quando comparada a situação original, sem o absorvedor de vibração. Porem, uma deficiência dos absorvedores de vibração lineares típicos e sua estreita faixa de frequência de operação. Para superar essa deficiência, muitas tentativas de solução usando subsistemas não lineares tem sido propostas na literatura, ja que se apropriadamente projetados, eles podem aumentar a faixa de frequência de absorção de vibração e/ou melhorar a redução das amplitudes de vibração do sistema primário. Contudo, a síntese e o projeto de tais absorvedores não lineares não e tão simples e direta como no caso linear. Baseado na geometria de uma topologia proposta e encontrada na literatura, que compreende a inclusão de uma montagem do tipo snap through truss no lugar da mola linear do absorvedor de vibração, este trabalho tem intenção de apresentar um estudo sobre o projeto e otimização de um absorvedor dinâmico de vibrações não linear. Portanto, o efeito dos parâmetros do absorvedor e analisado quanto as perspectivas de redução das amplitudes de vibração do sistema principal como também de aumento da faixa de frequência de operação. A analise paramétrica do absorvedor foi promovida para responder questões sobre as variáveis de projeto, tanto físicas como geométricas. Realizou-se otimização do absorvedor com objetivo de sintoniza-lo a frequência de trabalho desejada, através de busca extensiva e algoritmos genéticos. Os resultados mostram que o absorvedor não linear proposto pode ser mais efetivo que seu correspondente linear em ambos os aspectos, na redução da máxima amplitude de vibração e no aumento da faixa de frequência de absorção. Portanto, apesar da dificuldade inicial de projeto, esse tipo de absorvedor representa uma alternativa interessante na atenuação das amplitudes de vibração ao longo de uma extensa faixa de frequência. / Dynamic vibration absorbers are commonly used in several applications in order to reduce undesired vibration amplitudes of vibrating machinery and structures. The concept of a linear vibration absorber is based on the idea of designing a subsystem with a resonance frequency coincident with a given frequency of interest such that the vibration amplitude of the primary system is significantly reduced when compared to the original situation (without the vibration absorber). But one of the known handicaps of typical linear vibration absorbers is their narrow frequency range of operation. To overcome this handicap, a number of tentative solutions have been proposed in the literature using nonlinear subsystems. If properly designed, they could enlarge the frequency range of vibration absorption and/or improve vibration reduction of the primary system. However, the synthesis and design of such nonlinear absorbers are not as straightforward as for their linear counterpart. A proposed design found in the open literature consists of replacing the linear spring of the vibration absorber by a nonlinear snap-through truss. This work aims to present a study on the design and optimization of a nonlinear dynamic vibration absorber based on snap-through absorber geometry. The effect of the absorber parameters was analyzed on both, the primary system vibration amplitude reduction and the frequency range of operation. Parametric analyses of the absorber were carried out to answer questions about the physical and geometric design variables. The absorber optimization was performed in two different ways, by extensive search and genetic algorithms, in order to tune it in the desired working frequency. The results show that the proposed nonlinear vibration absorber may be more effective than its linear counterpart both in terms of maximum vibration amplitude reduction and absorption frequency-range. Therefore, despite the increased design complexities such an absorber is an interesting alterna- tive in attenuating vibration amplitudes over a wide frequency range.
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Internal Resonances in Vibration Isolators and Their Control Using Passive and Hybrid Dynamic Vibration AbsorbersDu, Yu 06 May 2003 (has links)
Conventional isolation models deal with massless isolators, which tend to overestimate the isolator performance because they neglect the internal resonances (IRs) due to the inertia of the isolator. Previous researches on the IR problem is not adequate because they only discussed this problem in terms of vibration based on single degree-of-freedom (SDOF) models. These studies did not reveal the importance of the IRs, especially from the perspective of the noise radiation. This dissertation is novel compared to previous studies in the following ways: (a) a three-DOF (3DOF) model, which better represents practical vibration systems, is employed to investigate the importance of the IRs; (b) the IR problem is studied considering both vibration and noise radiation; and (c) passive and hybrid control approaches using dynamic vibration absorbers (DVAs) to suppress the IRs are investigated and their potential demonstrated.
The 3DOF analytical model consists of a rigid primary mass connected to a flexible foundation through three isolators. To include the IRs, the isolator is modeled as a continuous rod with longitudinal motion. The force transmissibility through each isolator and the radiated sound power of the foundation are two criteria used to show the effects and significance of the IRs on isolator performance. Passive and hybrid DVAs embedded in the isolator are investigated to suppress the IRs. In the passive approach, two
DVAs are implemented and their parameters are selected so that the IRs can be effectively attenuated without significantly degrading the isolator performance at some other frequencies that are also of interest. It is demonstrated that the passive DVA enhanced isolator performs much better than the conventional isolator in the high frequency range where the IRs occur. The isolator performance is further enhanced by inserting an active force pair between the two passive DVA masses, forming the hybrid control approach. The effectiveness and the practical potential of the hybrid system are demonstrated using a feedforward control algorithm. It is shown that this hybrid control approach not only is able to maintain the performance of the passive approach, but also significantly improve the isolator performance at low frequencies. / Ph. D.
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Usure ondulatoire en transport ferroviaire: Mécanismes et réduction/Rail Corrugation in Railway Transport: Mechanism and MitigationCollette, Christophe G. R. L. 05 July 2007 (has links)
L'usure ondulatoire des rails associée aux vibrations de torsion des essieux de métro a été mise en évidence il y a près d'un demi siècle. L'utilisation d'absorbeurs dynamiques comme solution potentielle à ce problème a été suggérée pour la première fois dans le projet américain du TCRP "Rail Corrugation Mitigation in Transit" en 1998. Cette thèse, réalisée dans le cadre du projet européén "Wheel-rail CORRUGATION in Urban transport", a pour objectif de concevoir un absorbeur dynamique et d'étudier son influence sur la réduction de l'usure ondulatoire liée aux vibrations de torsion. Dans le cadre de ce travail, d'autres types d'usure ondulatoire ont également été traités par des absorbeurs dynamiques.
Les trois premiers chapitres de cette thèse sont dédiés à la description des différents types d'usure ondulatoire et à la présentation des méthodes de prédiction. La méthode de dimensionnement des absorbeurs dynamiques est présentée au chapitre 4, ainsi que quelques perspectives de leur efficacité à réduire l'usure ondulatoire. Dans le chapitre 5, un tronçon réel du RER parisien a été étudié. D'une part les prédictions obtenues par différentes méthodes ont été comparées aux mesures sur site. D'autre part, le bénéfice résultant de l'utilisation d'un absorbeur dynamique a été étudié numériquement. Dans le chapitre 6, le cas de l'usure ondulatoire liée aux vibrations de torsion a été étudié spécifiquement. Un absorbeur dynamique a été développé pour réduire ce type d'usure ondulatoire. Son efficacité a été évaluée théoriquement et numériquement, avec un modèle multi-corps flexible du véhicule et de la voie. Dans le chapitre 7, un absorbeur dynamique visant à réduire les vibrations de torsion d'un essieu de métro à échelle réduite a été construit au laboratoire. Son efficacité a été validée expérimentalement en reproduisant les conditions d'apparition des vibrations de torsion de l'essieu sur le banc d'essais du Laboratoire des Technologies Nouvelles de l'INRETS. La correspondance entre les prédictions d'usure à échelle réduite et à échelle réelle a été établie. Une demande de brevet a été déposée par le Laboratoire des Structures Actives pour ce système (N° 06120344.4).
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[en] VIBRATION CONTROL OF SLENDER TOWERS WITH A PENDULUM ABSORBER / [pt] ABSORSOR PENDULAR PARA CONTROLE DE VIBRAÇÕES DE TORRES ESBELTASDIEGO ORLANDO 24 July 2006 (has links)
[pt] Nesse trabalho, estuda-se o desempenho de um absorsor
pendular no
controle de vibrações de torres altas e esbeltas,
ocasionadas por carregamentos
dinâmicos, tais como, por exemplo, cargas ambientais. Em
virtude da
possibilidade de oscilações de grande amplitude, considera-
se na modelagem do
problema a não-linearidade do pêndulo. O principal
objetivo é estudar o
comportamento do sistema torre-pêndulo, submetido a um
carregamento
harmônico, no regime não-linear, abordando-se aspectos
gerais ligados à
estabilidade dinâmica. Apresenta-se, inicialmente, a
formulação necessária para
obter o funcional de energia do sistema coluna-pêndulo,
tanto para o caso linear
quanto para o caso não-linear, do qual derivam-se as
equações diferenciais
parciais de movimento. A partir das equações lineares,
obtêm-se as freqüências
naturais e modos de vibração para alguns casos relevantes
de coluna. A seguir,
com base na análise modal do sistema coluna-pêndulo,
deriva-se um modelo de
dois graus de liberdade capaz de descrever com precisão o
comportamento do
sistema na vizinhança da freqüência fundamental da coluna,
do qual obtêm-se as
equações de movimento e as equações de estado não-
lineares. Uma análise
paramétrica detalhada das oscilações não-lineares do
sistema coluna-pêndulo
demonstra que o absorsor pendular passivo pode reduzir ou
amplificar a resposta
da coluna. No estudo da influência da não-linearidade
geométrica do pêndulo,
verifica-se a importância dessa na resposta do sistema,
evidenciando que a nãolinearidade
não pode ser desprezada nessa classe de problema. Por fim,
com base
nos resultados, propõe-se um absorsor pendular híbrido. Os
estudos revelam que
este controle é mais eficiente que o passivo e que não
requer grande gasto de
energia. / [en] In the present work the performance of a pendulum absorber
in the vibration
control of tall and slender towers, caused by dynamic
loads, such as,
environmental loads, is studied in detail. Due to the
possibility of large amplitude
oscillations, the non-linearity of the pendulum is
considered in the modeling of
the problem. The main objective of this research is to
study the behavior of the
tower-pendulum system, submitted to a harmonic load, in
the nonlinear regimen,
with emphasis on general aspects related to its dynamic
stability. It is presented,
initially, the formulation necessary for the derivation of
the system´s energy
functional, both for the linear and the nonlinear cases,
from which the partial
differential equations of motion are derived and the
vibration frequencies and
related vibration modes are obtained. Then, based on the
modal analysis of the
column-pendulum system, a two degrees of freedom model,
capable of describing
with precision the behavior of the system in the
neighborhood of the fundamental
frequency of the column is derived, from which the
equations of motion and the
nonlinear state-space equations are obtained. A detailed
parametric analysis of the
nonlinear oscillations of the system is carried out. It
shows that the pendulum may
reduce or amplify the response of the column. The results
show a marked
influence of the geometric not-linearity of the pendulum
on the response of the
system, showing that its not-linearity cannot be neglected
in this class of
problems. Finally, based on the results, a hybrid control
approach is proposed.
These studies show that this control strategy is more
efficient than the passive
control alone and that it does not require a large amount
of energy.
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