Rozprawy doktorskie na temat „Structure vibration”
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Griffin, Steven F. "Acoustic replication in smart structure using active structural/acoustic control". Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13085.
Pełny tekst źródłaKari, Leif. "Structure-borne sound properties of vibration isolators /". Stockholm, 1998. http://www.lib.kth.se/abs98/kari0312.pdf.
Pełny tekst źródłaSénéchal, Aurélien. "Réduction de vibrations de structure complexe par shunts piézoélectriques : application aux turbomachines". Phd thesis, Conservatoire national des arts et metiers - CNAM, 2011. http://tel.archives-ouvertes.fr/tel-00862517.
Pełny tekst źródłaPurohit, Ashish. "Aeroacoustics of a vibrating structure in flow". Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7077.
Pełny tekst źródłaSun, Xiangkun. "Elastic wave propagation in periodic structures through numerical and analytical homogenization techniques". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC041/document.
Pełny tekst źródłaIn this work, the multi-scale homogenization method, as well as various non homogenization methods, will be presented to study the dynamic behaviour of periodic structures. The multi-scale method starts with the scale-separation, which indicates a micro-scale to describe the local behaviour and a macro-scale to describe the global behaviour. According to the homogenization theory, the long-wave assumption is used, and the unit cell length should be much smaller than the characteristic length of the structure. Thus, the valid frequency range of homogenization is limited to the first propagating zone. The traditional homogenization model makes use of material properties mean values, but the practical validity range is far less than the first Bragg band gap. This deficiency motivated the development of new enriched homogenized models. Compared to traditional homogenization model, higher order homogenized wave equations are proposed to provide more accuracy homogenized models. Two multi-scale methods are introduced: the asymptotic expansion method, and the homogenization of periodic discrete media method (HPDM). These methods will be applied sequentially in longitudinal wave cases in bi-periodic rods and flexural wave cases in bi-periodic beams. Same higher order models are obtained by the two methods in both cases. Then, the proposed models are validated by investigating the dispersion relation and the frequency response function. Analytical solutions and wave finite element method (WFEM) are used as references. Parametric studies are carried out in the infinite case while two different boundary conditions are considered in the finite case. Afterwards, the HPDM and the CWFEM are employed to study the longitudinal and transverse vibrations of framed structures in 1D case and 2D case. The valid frequency range of the HPDM is re-evaluated using the wave propagation feature identified by the CWFEM. The relative error of the wavenumber by HPDM compared to CWFEM is illustrated in the function of frequency and scale ratio. Parametric studies on the thickness of the structure is carried out through the dispersion relation. The dynamics of finite structures are also investigated using the HPDM and CWFEM
Dayou, Jedol. "Global control of flexural vibration of a one dimensional structure using tuneable vibration neutralisers". Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310842.
Pełny tekst źródłaBaran, Ismet. "Optimization Of Vibration Characteristics Of A Radar Antenna Structure". Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612978/index.pdf.
Pełny tekst źródłas performance in an adverse manner. The influence of deformations and vibrations are important on array antenna structures, since they cause a change in orientation of elements of the phased array antenna which affects the gain of the antenna negatively. In this study, vibration characteristics of a particular radar antenna structure are optimized using topology and stiffener design optimization methods such that negative effects of mechanical vibrations on functional performance of radar antenna are minimized. Topology and stiffener design optimization techniques are performed separately by the use of ANSYS Finite Element (FE) software in order to modify the design of the radar antenna structure such that its critical natural frequencies in the range of 0-500 Hz are shifted out of the dominant peak sinusoid frequency range of the air platform. As a result of this, it will be possible to minimize the vibration response of the phased array elements in the frequency range of 0-500 Hz
hence better antenna performance can be achieved. In addition to this, it will also be possible to minimize the broadband random vibration response of base excitation coming from air platform.
Tratch, Jorge. "Vibration transmission through machinery foundation and ship bottom structure". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15216.
Pełny tekst źródłaMICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Includes bibliographical references.
by Jorge Tratch Junior.
Mech.E
Thomas, Benjamin. "Dynamique d’une structure complexe à non linéarités localisées sous environnement vibratoire évolutif : Application à l'isolation vibratoire d'un équipement automobile". Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0106/document.
Pełny tekst źródłaThis research work regards the development of a complex structure model with non-linear viscoelastic components. The purpose of this study is to simulate the response of this structure submitted to a random vibration excitation based on a power spectral density definition (PSD). The industrial applicative case is the vibratory insulation of a automotive engine cooling module supported by elastomer mounts. A brief review of elastomers behavior depending on solicitations types enables to identify the parameters of the different investigated models. Preliminary tests have been conducted to define the range of amplitudes of excitations and evaluate the internal warming of rubbers during the full structure validation test. The experimental characterization of the suspension is based on rubbers mounts and their interfaces with the cooling module, in order to take into account in a unique model all nonlinearities due to the viscoelastic behavior, the slidings, and the friction. Measured force-deflection hysteretic cycles in axial and radial direction are post-processed with an expert system developed to obtain the parameters of the retained model: the modified Dahl’s model, generalized to viscoleastic aspect. This process has been developed with Octave/Matlab code. Interpolation and extrapolation methods enable to obtain a good model response on the global operating range. These methods have been coded in an Abaqus UserSubroutine. Imposing random vibration excitation of a non linear mechanical system based on PSD imposes to take into account signal processing aspects. To evaluate response levels versus norms requirements, it’s mandatory to consider the time-frequency transfer. In addition, the size and the complexity of the total finite element model of the industrial structure don’t allow a global resolution in the time domain for all the degrees of freedom. Homogenization and dynamic reduction techniques are used to evaluate the response of the system submitted to large frequency range excitations, and to analyse the behavior of the suspension
Thomas, Benjamin. "Dynamique d’une structure complexe à non linéarités localisées sous environnement vibratoire évolutif : Application à l'isolation vibratoire d'un équipement automobile". Electronic Thesis or Diss., Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0106.
Pełny tekst źródłaThis research work regards the development of a complex structure model with non-linear viscoelastic components. The purpose of this study is to simulate the response of this structure submitted to a random vibration excitation based on a power spectral density definition (PSD). The industrial applicative case is the vibratory insulation of a automotive engine cooling module supported by elastomer mounts. A brief review of elastomers behavior depending on solicitations types enables to identify the parameters of the different investigated models. Preliminary tests have been conducted to define the range of amplitudes of excitations and evaluate the internal warming of rubbers during the full structure validation test. The experimental characterization of the suspension is based on rubbers mounts and their interfaces with the cooling module, in order to take into account in a unique model all nonlinearities due to the viscoelastic behavior, the slidings, and the friction. Measured force-deflection hysteretic cycles in axial and radial direction are post-processed with an expert system developed to obtain the parameters of the retained model: the modified Dahl’s model, generalized to viscoleastic aspect. This process has been developed with Octave/Matlab code. Interpolation and extrapolation methods enable to obtain a good model response on the global operating range. These methods have been coded in an Abaqus UserSubroutine. Imposing random vibration excitation of a non linear mechanical system based on PSD imposes to take into account signal processing aspects. To evaluate response levels versus norms requirements, it’s mandatory to consider the time-frequency transfer. In addition, the size and the complexity of the total finite element model of the industrial structure don’t allow a global resolution in the time domain for all the degrees of freedom. Homogenization and dynamic reduction techniques are used to evaluate the response of the system submitted to large frequency range excitations, and to analyse the behavior of the suspension
Dhruna, Chetan J. "Experimentally-Based Analytical Prediction of Structural Vibration". Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35875.
Pełny tekst źródłaMaster of Science
Ng, S. L. D. "Transmission of ground-borne vibration from surface railway trains". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243156.
Pełny tekst źródłaBadiane, Doudou. "Simulation numérique et étude expérimentale d'un viscosimètre à principe vibrant". Thesis, Orléans, 2012. http://www.theses.fr/2012ORLE2057/document.
Pełny tekst źródłaKnowing the viscosity becomes increasingly a major challenge in leading-edge technologies (biomedical, petrochemical, printing, cosmetic, food industry, etc). This study presents a viscosity sensor based on a thin beam immersed in a newtonian fluid and subjected to transverse vibrations due to an electromechanical excitation system. The damped vibration can be used to evaluate the fluid viscosity and density by measuring the beam’s resonance characteristics (amplitude, frequency). This measurement is done by an electromagnetic feedback circuit. In this work, numerical model and experimental studies of the vibrating viscometer are conducted to better understand the influencing factors of the sensor’s operation. The different investigations carried out in this work are of great importance for the viscometer optimization on one hand. On the other hand, it’s a contribution to all studies dealing with the aspect of fluid-structure-electromagnetism coupling
Asyikin, Muhammad Tedy. "CFD Simulation of Vortex Induced Vibration of a Cylindrical Structure". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18814.
Pełny tekst źródłaSANTEE, DONALD MARK. "NONLINEAR VIBRATION AND STRUCTURE STABILITY ANALYSIS OF IMPERFECTION SENSITIVE ELEMENTS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1897@1.
Pełny tekst źródłaO objetivo desta tese é estudar os mecanismos de escape em sistemas estruturais sensíveis a imperfeições quando submetidos a certas classes de carregamentos dinâmicos, identificar os parâmetros que controlam o escape e criar critérios capazes de prever a fronteira de escape e a perda de estabilidade da estrutura no espaço dos parâmetros de controle. Isto permitirá um melhor entendimento dos processos de perda de estabilidade e servirá de base para o cálculo e controle da integridade dessas estruturas. Após a descrição dos fenômenos que podem ocorrer na dinâmica dessa classe de estruturas, são testados e adaptados alguns critérios existentes na literatura, que verificam a estabilidade de uma estrutura a partir do conhecimento dos parâmetros de controle. Em seguida estuda-se a evolução da estabilidade global do conjunto das soluções medida pela área da bacia de atração, e pelas características de sua fronteira. Desenvolvem-se expressões gerais para o critério de Melnikov, e mostra-se, a partir de perturbações aleatórias nos parâmetros de controle e na força externa, que essas expressões podem ser tomadas como um limite inferior para o carregamento de escape e conseqüentemente como uma contribuição para o desenvolvimento de critérios de projeto. Verifica-se também que os valores obtidos pelos critérios de escape podem ser tomados como limites superiores para o valor da força de escape.
The purpose of this thesis is to study the escape mechanisms in imperfection sensitive structural systems under certain dynamical loading conditions. Other objectives are to identify the parameters that control the escape phenomenon and to create some criteria capable of predicting the escape boundary and the structures stability in the control parameters space. This will allow a better understanding of the stability loss process and can serve as a basis to the integrity control and design of these structures. After a description of the phenomena that can occur in the dynamics of this class of structures, some predictive criteria, found in literature, that verify the structure stability based on the control parameters knowledge, are adapted and tested. Following is a study of the evolution of the global stability of the set of solutions measured by the basin of attraction area, and by the characteristics of its boundary. Some general expressions for the Melnikov criterion are developed, and it is shown by randomly perturbing the control parameters and the external force, that these expressions can be taken as a lower bound for the escape load, and consequently as a contribution to the development of design criteria. It is also observed that the values obtained by the escape criteria can be taken as an upper bound for the values of the escape force.
EL objetivo de esta tesis es estudiar los mecanismos de escape en sistemas extructurales que son sensibles a imperfecciones cuando son sometidos a ciertas clases de cargas dinámicas. Outro objetivo es identificar los parámetros que controlan el escape y crear criterios capaces de preveer la frontera de escape y la pérdida de estabilidad de la extructura en el espacio de los parámetros de control. Esto permitirá una mejor comprensión de los procesos de pérdida de estabilidad y servirá de base para el cálculo y control de la integridad de esas extructuras. Después de describir los fenómenos que pueden ocurrir en la dinámica de esta clase de extructuras, se prueban y adaptan algunos criterios existentes en la literatura, que verifican la estabilidad de una extructura a partir del conocimiento de los parámetros de control. Seguidamente, se estudia la evolución de la estabilidad global del conjunto de las soluciones, se dearrollan expresiones generales para el criterio de Melnikov, y se muestra, a partir de perturbaciones aleatorias en los parámetros de control y en la fuerza externa, que esas expresiones pueden ser tomadas como límite inferior para la carga de escape y conseqüentemente como una contribución para el desarrollo de criterios de proyecto. Se verifica también que los valores obtenidos por los criterios de escape pueden ser tomados como límites superiores para el valor de la fuerza de escape.
Wang, Wei-Hui. "Modelling machine induced noise and vibration in a ship structure". Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/2823.
Pełny tekst źródłaKim, Seungbo. "Structure-borne noise transmission through a multi-dimensional vibration isolator /". The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486399451959589.
Pełny tekst źródłaMartins, Daniel. "Vibration control on a tensegrity structure using shape memory alloys /". Bauru, 2019. http://hdl.handle.net/11449/183354.
Pełny tekst źródłaBanca: Marcos Silveira
Banca: Carlos de Marqui Junior
Resumo: Um sistema de tensegrity é composto por dois tipos de elementos, elementos de tração e compressão, os quais promovem a estabilidade estrutural do sistema, neste trabalho as partes de tração são cabos (cabos de aço), e as partes compressivas são barras de aço. Uma característica atrativa de uma estrutura de tensegridade é a capacidade de ser retrátil, por esta razão, é interessante para aplicações espaciais devido ao pequeno volume que ocupa um possível transporte para uma estação espacial. Em geral, essas estruturas podem ser grandes com muitas células repetitivas. Neste trabalho, estuda-se uma estrutura de tensegrity composta por dez células periódicas de barras e cabos. O modelo matemático, obtido pelo método dos elementos finitos, é validado experimentalmente considerando o caso de uma célula estrutural. Para tornar o sistema adaptável à excitação externa, um dos cabos de aço na célula elementar é substituído por um fio de liga de memória de forma (SMA) que permite que as características dinâmicas do sistema sejam alteradas de acordo com uma corrente elétrica aplicada no SMA, para que através do efeito Joule a liga seja aquecida. Diferentes configurações para a colocação do cabo SMA são estudadas com o objetivo de reduzir as amplitudes de vibração para uma excitação de força harmônica.
Abstract: A tensegrity system is composed by two types of elements, tensile and compressive parts, which promotes the structural stability of the system, in this case the tensile parts are cables (steel cables), and the compressive parts are bars, in this work made of steel. An attractive characteristic of a tensegrity structure is the capability to be deployable, for this reason, is interesting for space applications due to the small volume that it occupies in a possible transport to a station outside the Earth. In general, these structures can be large with many repetitive cells. In this work, a tensegrity boom structure consisting of ten periodic cells made of bars and cables is studied. The mathematical model, obtained by finite element method is validated experimentally considering the case of one structural cell. In order to make the system adaptable to external excitation, one of the steel cables in the elementary cell is replaced by a SMA (shape memory alloy) wire (Nitinol) allowing the dynamics characteristics of the system to be changed according to an electrical current applied to the SMA, to heat the alloy through Joule effect. Different configurations for placing the SMA cable are studied with the objective of reducing the vibration amplitudes for harmonic force excitation.
Mestre
Fraser, Grant. "Structure borne sound in motor-vehicles using statistical energy analysis". Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/1285.
Pełny tekst źródłaCôté, François. "Développement par éléments finis de la région active d'une structure intelligente multi-couches". Sherbrooke : Université de Sherbrooke, 2002.
Znajdź pełny tekst źródłaZhang, Qingwen. "Models of a standing human body in structural vibration". Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/models-of-a-standing-human-body-in-structural-vibration(00dfea7a-dbff-4396-b816-8e81a1891fa8).html.
Pełny tekst źródłaMURUGAN, JAYA MAHESH. "Vibration monitoring and control of industrial structures". Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2858351.
Pełny tekst źródłaHui, Yi. "Development and experimental validation of vibration based damage indicator on a specific twin-wall sandwich structure". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC032.
Pełny tekst źródłaStructural health monitoring (SHM) has attracted much attention in many engineering fields like civil, aeronautic, mechanical industry, etc. since it is important to monitor the healthy condition of the operational structure in order to avoid unpredicted structural failure which may have severe consequences. The four-level damage identification process: existence, localization, severity and prediction of damage evolution, can be partly realized if a suitable indicator is chosen. It exists different damage indicators whose application range of frequency spans from vibrational response at low frequencies to the ultrasonic regimes in the mega hertz range.The sandwich structures are widely used in various engineering applications due to its exceptionally high flexural stiffness-to-weight ratio compared to monocoque structures. In this thesis a specified twin-wall sandwich structure in polypropylene was studied and vibration-based indicators were designed by taking use of its relative high damping and propagation directivity characteristics. Numerical investigations on different damage scenarios (i.e., different types of defect and their combinations) and an associated discussion on the range of application were first carried out. Experimental configuration was easily realized with the help of a scanning laser doppler vibrometer (SLDV). Defect was successfully detected by the proposed indicators
Ozsoy, Serhan. "Vibration Induced Stress And Accelerated Life Analyses Of An Aerospace Structure". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12606966/index.pdf.
Pełny tekst źródła#8217
s dynamic characteristics and varying loadings. Therefore, experimental, numerical or a combination of both methods are used for fatigue evaluations. Fatigue failure can occur on systems and platforms as well as components to be mounted on the platform. In this thesis, a helicopter&
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s Missile Warning Sensor - Cowling assembly is analyzed. Analytical, numerical and experimental approaches are used wherever necessary to perform stress and fatigue analyses. Operational flight tests are used for obtaining the loading history at the analyzed location by using sensors. Operational vibration profiles are created by synthesizing the data (LMS Mission Synthesis). Numerical fatigue analysis of the assembly is done for determining the natural modes and the critical locations on the assembly by using a finite element model (MSC Fatigue). In addition, numerical multiaxial PSD analysis is performed for relating the experimental results (Ansys). Residual stresses due to riveting are determined (MSC Marc) and included in experimental analysis as mean stresses. Bolt analysis is performed analytically (Hexagon) for keeping the v assembly stresses in safe levels while mounting the experimental prototype to the test fixture. Fatigue tests for determining the accelerated life parameters are done by an electromagnetic shaker and stress data is collected. Afterwards, fatigue test is performed for determining whether the assembly satisfies the required operational life. Resonance test is performed at the frequency in which the critical location is at resonance, since there was no failure observed after fatigue testing. A failure is obtained during resonance test. At the end of the study, an analytical equation is brought up which relates accelerated life test durations with equivalent alternating stresses. Therefore, optimization of the accelerated life test duration can be done, especially in military applications, by avoiding the maximum stress level to reach or exceed the yield limit.
Iu, Vai-pan, i 姚偉彬. "Nonlinear vibration analysis of multilayer sandwich structure by incremental finite elements". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31230623.
Pełny tekst źródłaPriest, Eric M. "Free Vibration Response Comparison of Composite Beams with Fluid Structure Interaction". Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/17443.
Pełny tekst źródłaThe analysis of the dynamic response of a vibrating structure in contact with a fluid medium can be interpreted as an added mass effect known as the Fluid Structure Interaction (FSI) problem. This effect is critical in the study of composites for marine applications since the densities of the composites and water are relatively close to one another. In this study, experimental testing was conducted to compare the free vibration response of composite beams in air with those in FSI immersed in water. Composite beams with six layers of non-biased, plain weave, 6 oz E-glass were used with two different layer orientations and boundary conditions. Five samples were layered at the 0 and 90 degree orientations and five samples were layered at the plus and minus 45 degree orientation. The Digital Image Correlation (DIC) technique was used to test each of the ten samples in a cantilever boundary condition with an initial displacement to induce a free vibration response both in air and immerse in water. A High Speed Camera (HSC) was also used to gain further frequency information during each of these tests. A second set of two composite beams were constructed with 16 layers at both of the described orientations. These were instrumented with accelerometers to conduct a modal analysis from an impact hammer test. These tests were conducted with the beams in a free-free boundary condition while in air and immersed in water. Prior to conducting these tests, an aluminum beam was tested with the same conditions to verify the waterproofing of the accelerometers and to ensure valid data was collected. The findings of this study will provide a better understanding for the use of composite materials in marine applications where various excitations can occur.
Brandsen, Jacobus Daniel. "Prediction of axial compressor blade vibration by modelling fluid-structure interaction". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85616.
Pełny tekst źródłaENGLISH ABSTRACT: The Council for Scientific and Industrial Research has developed a vibration excitation system. The system is designed to excite the rotor blades of an axial compressor in the specified vibration mode and at the specified frequency. The vibration excitation system was tested on Stellenbosch University’s Rofanco compressor test bench. A two-way staggered fluid-structure interaction (FSI) model was created that was capable of simulating the vibration of the rotor blades excited by the system. The results of the FSI model were verified using available experimental data. It was concluded that the FSI model is able to recreate the vibration excited by the system to within the desired level of accuracy. In addition, the results of the FSI model showed that the vibration excitation system should be able to excite the blades in the selected vibration mode and at the selected frequency provided that the excitation frequency is close the natural frequency of the first bending mode. The results also suggested that a transient computational fluid dynamics model should be sufficient for the prediction of the aerodynamic forces acting on the rotor blades. Furthermore, a one-way staggered FSI model should be adequate for calculating the motions of the blades.
AFRIKAANSE OPSOMMING: Die Wetenskaplike en Nywerheidnavorsingsraad het ’n vibrasie-opwekkingstelsel ontwerp om die rotorlemme van ’n aksiaalvloei kompressor in die gespesifiseerde vibrasiemodus en teen die gespesifiseerde frekwensie op te wek. Die vibrasieopwekkingstelsel is met behulp van die Universiteit Stellenbosch se Rofanco kompressortoetsbank getoets. Daarna is ’n tweerigting vloeistof-struktuur-interaksie model geskep om die vibrasie van die rotorlemme, wat deur die stelsel opgewek is, te simuleer. Beskikbare eksperimentele data is gebruik om die resultate van die vloeistof-struktuur-interaksie model te bevestig. Die gevolgtrekking is gemaak dat die model wél die vibrasie van die lemme met die nodige akkuraatheid kan simuleer. Die resultate van die vloeistof-struktuur-interaksie model toon ook dat die stelsel die lemme in die gekose vibrasiemodus en teen die gekose frekwensie behoort te kan opwek, solank die opwekkingsfrekwensie na aan die natuurlike frekwensie van die eerste buigmodus is. Voorts dui die resultate daarop dat ’n berekeningsvloeimeganika model die aërodinamiese laste van die lemme sal kan voorspel. ’n Eenrigting vloeistof-struktuur-interaksie model behoort voldoende te wees om die beweging van die rotorlemme te bereken.
Chaudhari, Devendra. "Experiments on the vibration control of a flexible structure using FPGA". Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10014956.
Pełny tekst źródłaThe goal of this project is to develop, implement and test experimentally a state-feedback controller for the vibration control of a flexible structure, using an Active Mass Damper (AMD). Based on a previously developed model of the structure, a state-feedback controller with full observer has been implemented in the LabView (Laboratory Virtual Instrument Engineering Workshop) computational environment using the myRIO FPGA board (Field Programmable Gate Array). Experimental results show that the controller improves the structural response significantly by reducing the amplitude and duration of the response when the structure is subject to random earthquake-like excitations.
Iu, Vai-pan. "Nonlinear vibration analysis of multilayer sandwich structure by incremental finite elements /". [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12322945.
Pełny tekst źródłaRobu, Bogdan. "Active vibration control of a fluid/plate system". Phd thesis, Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1103/.
Pełny tekst źródłaWe consider the problem of the active reduction of structural vibrations of a plane wing induced by the sloshing of large masses of fuel inside partly full tank. This study focuses on an experimental device composed of an aluminum rectangular plate equipped with piezoelectric actuators/sensors at the clamped end and with a cylindrical tip-tank, more or less filled with liquid, at the opposite free end. The control is performed through piezoelectric actuators and the main difficulty comes from the complex coupling between the flexible modes of the wing and the sloshing modes of the fuel. First, a partial derivative equation model is computed by coupling a plate equation with a Bernoulli equation for the fluid motion. After analyzing the energetic contribution of each mode, a state space approximation is established. After a model matching procedure, a control is computed by using the pole placement method and the H-infinity theory. Due to the large scale of the synthesis model and to the simultaneous performance requirements, a reduced-order H-infinity controller is computed using the HIFOO 2. 0 package and tested on the experimental device for different filling levels. Finally, the problem of simultaneous control with a reduced order HIFOO controller is tackled. Experimental results of this non-convex optimization problem are given and commented
Deng, Fengyan. "Contrôle modal autoadaptatif de vibrations de structures évolutives". Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00749905.
Pełny tekst źródłaDickens, John D. Aerospace & Mechanical Engineering Australian Defence Force Academy UNSW. "Dynamic characterisation of vibration isolators". Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace and Mechanical Engineering, 1998. http://handle.unsw.edu.au/1959.4/38675.
Pełny tekst źródłaJubinville, François. "Calcul de la réponse d'une structure soumise à une excitation aléatoire". Sherbrooke : Université de Sherbrooke, 2001.
Znajdź pełny tekst źródłaDucarne, Julien. "Modélisation et optimisation de dispositifs non-linéaires d’amortissement de structures par systèmes piézoélectriques commutés". Thesis, Paris, CNAM, 2009. http://www.theses.fr/2009CNAM0633/document.
Pełny tekst źródłaIn order to reduce the vibrations of a mechanical structure, one can use piezoelectric elements connected to passive electrical circuits. The goal is to achieve the same efficiency as active vibration control without the associated complexity and energy consumption. First the use of a resistor (with an effect similar to viscous damping) and eventually of an inductor (allowing the creation of a tuned resonator) for the circuit is considered. These systems have interesting properties, but are not very efficient, except in the case of a finely tuned inductor. In order to obtain good performance without requiring a precise tuning, a switching circuit is considered. The switching process is synchronized on the vibrations, and the effect of the free electric charge (similar to a dry damping) reduces the vibrations. This system is self-adaptive and can be self-powered. However, the strong non-linearities create a high frequency excitation which may disturb the switch timing. Two different reduced electromechanical models (analytical and finite element) are proposed, allowing a description of the whole system dynamics with accuracy and to emphasize the coupling between one vibration mode and the circuit. This coupling is found to be decisive for the performance in vibration reduction. A study of the influence of various parameters allow the optimisation of the piezoelectric elements, electric circuits and switch timing. These results are experimentally tested and a good agreement with the predictions is obtained ; the difficulty of switch timing is also noticed
Pan, Zhifang. "AB initio calculation of vibration frequencies, infrared intensities, and structures for: H₄+, LI₂H₂+ and LI₄+, and deuterated analogs : AB initio study of potential surface for decomposition of H₄ cluster derived from charge neutralization of H₄+Ion : AB initio study of the structures and vibrational frequencies of CF₄-and CF₃CL-". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/27073.
Pełny tekst źródłaBail, Justin L. "Non-desctructive investigation & FEA correlation on an aircraft sandwich composite structure". Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1196702586.
Pełny tekst źródła"December, 2007." Title from electronic thesis title page (viewed 02/25/2008) Advisor, Wieslaw Binienda; Faculty readers, Craig Menzemer, Robert Goldbert; Department Chair, Wieslaw Binienda; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
Zäll, Emma. "Footbridge Dynamics : Human-Structure Interaction". Licentiate thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224527.
Pełny tekst źródłaPå grund av estetiska skäl och en ökad efterfrågan på kostnadseffektiva och miljövänliga konstruktioner är merparten av de gångbroar som konstrueras idag förhållandevis lätta och slanka. Med anledning av detta ökar risken för att stora svängningar uppstår på grund av dynamisk belastning från människor på bron. För att motverka att detta inträffar kräver dagens normer att komforten verifieras för gångbroar med egenfrekvenser inom området för människans stegfrekvens. Komforten verifieras genom att säkerställa att ett visst accelerationskriterium inte överskrids. För detta ändamål finns handböcker som tillhandahåller förenklade beräkningsmetoder för uppskattning av accelerationsnivåer. Brister i dessa beräkningsmetoder har emellertid identifierats. För det första kan olika typer av människa-bro-interaktion (HSI) ha en betydande inverkan på responsen hos vissa broar. Exempel på en HSI-effekt är att brons modala egenskaper förändras när människor befinner sig på bron; i huvudsak sker en ökning av brons dämpning. Om denna effekt inte tas i beaktande föreligger stor risk att överskatta förväntade accelerationsnivåer. För det andra är kraften från en löpare större än kraften från en gående person vilket gör att en ensam löpare på en gångbro kan ge upphov till accelerationsnivåer som överskrider gränsvärdena för komfort. Löpande personer är därför ett mycket relevant lastfall. Befintliga normer uttrycker inte explicit att någon av dessa aspekter bör tas i beaktande. Behovet av förbättrade riktlinjer för hur normerna bör tillämpas är därför mycket stort och i framtiden kan det bli nödvändigt att kräva att både HSI-effekter och löparlaster tas i beaktande. Därför syftar denna licentiatavhandling till att bidra till en fördjupad förståelse inom dessa två ämnen, med huvudfokus på ovan nämnda HSI-effekt i allmänhet och hur den kan beaktas på ett enkelt, noggrant och tidseffektivt sätt i synnerhet. En numerisk undersökning av HSI-effekten och dess inverkan på den vertikala responsen hos en gångbro genomfördes. Resultaten visar att HSI-effekten reducerar den maximala accelerationen och att störst reduktion erhålls då folksamlingen och bron har ungefär samma egenfrekvens och då folksamlingens massa är stor i förhållande till brons massa. Vidare utvärderades två förenklade metoder för beaktande av HSI-effekten vilka kan implementeras av konstruktörer med grundläggande kunskaper inom strukturdynamik. Det konstaterades att båda metoderna uppskattar HSI-effekten såväl som brons respons förhållandevis väl samtidigt som de reducerar beräkningstiden något jämfört med mer avancerade metoder. Effekten av löpare på gångbroar studerades genom en fallstudie med fältmätningar. Utifrån resultaten från dessa fältmätningar kunde det konstateras att accelerationsgränsen som anges i normerna överskreds när en ensam löpare sprang över bron men inte när en grupp på sju personer gick i takt över samma bro. Därför drogs slutsatsen att löparlaster bör tas i beaktande vid dimensionering av en gångbro.
QC 20180320
Robert, Séverine. "Description globale de la structure de vibration-rotation de la molécule d'acétylène". Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210307.
Pełny tekst źródłaConcernant l'isotopologue principal, $H^{12}C^{12}CH$, 14 nouvelles bandes ont été mises à jour à partir de spectres enregistrés en CRDS à Grenoble par A. Campargue et al. Une analyse rovibrationnelle globale a été effectuée jusqu'à une énergie de 8600 cm$^{-1}$. 10750 raies ont été ajustées simultanément sur les 12137 attribuées dans la littérature. 266 paramètres ont été déterminés par la méthode de moindres-carrés. La déviation standard sans dimension du fit est de 0.92. La bande $u_{5}$-$u_{4}$, centrée vers 117 cm$^{-1}$ a été simulée. La valeur du moment de transition associé, $
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
PONTE, ELAINE CRISTINA RODRIGUES. "EVALUATION OF REFINED MODELS FOR INSTABILITY AND VIBRATION OF TWO-DIMENSIONAL STRUCTURE". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11334@1.
Pełny tekst źródłaEste trabalho consiste em desenvolver e avaliar modelos clássicos de elementos finitos combinados com funções polinomiais adicionais, para a obtenção de cargas críticas de instabilidade e freqüências naturais de estruturas planas, com seus respectivos modos. O objetivo consiste em buscar uma sistemática confiável para obter estimativas de deformações localizadas em regime próximo ao colapso. Utiliza-se o método dos Elementos Finitos em combinação com o método clássico de Rayleigh-Ritz. Como elemento fundamental para tal estudo, emprega-se o elemento retangular de Barber-Weaver, que contém quatro nós, cada nó com duas translações e duas rotações independentes (equivalentes a uma rotação e uma distorção angular). Esse elemento é enriquecido com funções de deslocamentos adicionais internas e de contorno, em forma de séries polinomiais gerais. Esse conjunto de funções é incorporado nas expressões de energia para levar ao estabelecimento de matrizes de rigidez elástica, geométrica e de massa. Tais matrizes permitem estabelecer problemas generalizados de autovalor para obtenção de cargas críticas e freqüências, e respectivos modos de flambagem e vibração. Para os estudos numéricos comparativos apresentados nos exemplos, são implementadas diversas rotinas usando o software Maple 9.0. Os resultados mostram que a metodologia apresentada pode ser usada no desenvolvimento de uma técnica aplicável à obtenção de modos globais e localizados de instabilidade, quando há a combinação de efeitos não lineares geométricos e de material.
This work consists in developing and evaluating classical of finite element models combined with additional polynomial functions, to obtain critical loads of instability and natural frequencies of plane structures, and respective modes. The objective is to search for a reliable technique to get estimates of localized deformations near to collapse. The Finite Elements method is used in combination with the classic method of Rayleigh-Ritz. As a basic element for such study, the rectangular element of Barber-Weaver is used, containing four nodes, each one with two translations and two independent rotations (equivalents to a rotation and an angular distortion). This element is enriched with additional internal displacement functions and with functions on the boundary, forming general polynomial series. These nodal functions are incorporated in the energy expressions leading to the establishment of elastic stiffness, geometric, and mass matrices. Such matrices allow the establishment of generalized eigenvalue problems to obtain critical loads and frequencies, and the respective modes of buckling and vibration. For the comparative numerical studies presented in the examples, several routines are implemented using software Maple 9.0. The results show that the methodology presented herein can be used in the development of an applicable technique to the ascertainment of instability in global and located modes, when there is a combination of geometric nonlinear and material effects.
Lu, Ya Nan. "Static and forced vibration analysis of plane truss structure with geometrical nonlinearity". Thesis, University of Macau, 2015. http://umaclib3.umac.mo/record=b3335487.
Pełny tekst źródłaHsieh, Chih-Wei, i 謝志瑋. "Study of vibrational structure of vibration-based microgenerator". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/80537360038039425709.
Pełny tekst źródła國立中山大學
機械與機電工程學系研究所
92
The main components of the vibration-based microgenerator incorporate vibratile structure, magnetic thin film, and coils. In this thesis work, bulk-micromachining technology and laser-micromachining technology were used to fabricate the vibratile structure of the microgenerator. And this is the beginning of the development of the microgenerator. Bulk-micromachining technology was widely used in micro-electromechanical system (MEMS). The most advantage of the technology is that it can be integrated with IC process in the future. And the roughness of the wafer is the key point of the etching process. In addition, 355nm UV Nd:YAG laser was also used to fabricate the vibratile structure. The period of fabricating prototype can be shortened by laser-micromachining. In laser-micromachining system, the dual-prism was used to change the direction of the laser beam by adjusting the initial phase of one of the prisms. When the laser beam moves relatively to workstation, the cutting process can be proceeded. By this system, the cutting linewidth is controllable. This technology has be used to fabricate the microstructure successfully, and the aspect ratio is up to 10, and the feature size is 50µm. Circular spiral spring structure was fabricated successfully, and it is to be the vibratile structure of the microgenerator. Finite element software ANSYS was used to simulate the dynamic characterization of the vibratile structure and the vibration testing experiment was carried out. The result shows that the experimental resonant frequency is very close to the simulative resonant frequency. So this vibratile structure can be used in microgenerator.
Chen, Kuan-Chih, i 陳冠智. "Vibration Reduction Analysis of Dynamic Vibration Absorber in Beam Structure". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/wz8ssn.
Pełny tekst źródła國立臺北科技大學
製造科技研究所
105
In this paper, based on continuous system beam structure as a dynamic vibration absorber and analyzed the vibration reduction of beam structure. The equation of motion of the beam structure with base excitation is derived by using energy principle. The dynamic vibration absorber model of the continuous system is derived from the dynamic vibration absorber model with two-degree of freedom, and then the effect of vibration absorber on the structure of viscous damped beam is analyzed by Transfer Matrix Method. The influence of design parameters, which are the mass ratio and damping ratio, is analyzed to research the vibration reduction of the first two modes of the beam structure. When the resonance frequencies of the vibration absorber are the same as the excitation frequencies of the base, the amplitude of the free end of the beam structure is the smallest. Finally, the results show that the viscous damping is located on the maximum bending moment of the beam structure or absorber can reduce the amount of displacement in the resonance.
Li, Tai-Wei, i 李泰緯. "Vibration Control of a Frame Structure". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/62940964616049122921.
Pełny tekst źródłaChang, Sheng-Tien, i 張勝添. "Vibration Analysis of LCD TV Neck Structure". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/7yf5bd.
Pełny tekst źródła國立臺北科技大學
製造科技研究所
98
In the numerous liquid crystal product design, the neck design is very important. It will affect television''s balance, the unstable balanced design easy to create liquid crystal''s falling and to cause the product broken or falls to make consumer being injured. The major part of neck designs are use die casting, mainstream is light and thin design, so this article will to use punch method to manufacture neck to replace die casting method. This study is mainly using “finite element method” to simulate different strengthens form design and process in Modal analysis and Transient analysis. The result of research showed that from the transient analysis simulation and use of applied 20N force on LCD TV. Type3 is better than Type1 and Type2,it can effectively reduce time and improve the vibration attenuation phenomenon.
Hsu, Yu-Hsiung, i 言午裕雄. "Suspended Sediment Concentration Monitoring by Structure Vibration". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/72954591816062687641.
Pełny tekst źródła逢甲大學
土木暨水利工程博士學位學程
99
This study proposed an innovative method for real-time monitoring and testing of fluid density and suspended sediment concentration (SSC) based on the principle of acoustic vibration. Loading effects on the boundary of a vibrating tube from the surrounding fluids cause regular variations in the resonance frequencies in a vibrating tube or plate. Physical properties and variation mechanisms of the density and SSC influencing the test fluid were investigated. Measuring devices on established vibrating tubes and plates were used to measure the properties of resonance frequencies, and acoustic vibrations in the tubes and plates were tested using fluids of various densities and conditions. A strain gauge that could sense high frequencies was installed on the vibrating bodies and measured the vibration properties of the tubes or plates. The vibration signals were analyzed by Fourier transform to obtain the main resonance frequency. The preliminary experiment investigated the influences of immersion depth, structure, and arrangement (level or upright) of the vibrating bodies; the formal experiment investigated the impacts of fluid density, sediment particle size, SSC, and structural properties of the vibrating body on the resonance frequencies of the tube or plate. The results were further discussed and analyzed. This study also applied finite element analysis in COMSOL Multiphysics to construct a model and carry out a simulation, the results of which confirmed the experimental results. After comparison of the simulated results and experimental results under the various conditions of vibration tube and plate properties and fluid densities, regularities were found among the combinations of different modes with the structural properties of various vibrating bodies. The results of the sediment concentration experiment specifically indicated a corresponding trend between calibration concentration and resonance frequency, thereby establishing a relationship between SSC and resonance frequency.
Wu, Tong-Ching, i 吳東憬. "Vibration Analysis of Cone-type Shell Structure". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/12763223632869555808.
Pełny tekst źródła國立交通大學
機械工程系
88
In this thesis, vibration characteristics of the conical shell structures are studied, especially the characteristics of concentric modes with circumferential wave numbers equaling to one. For given edge loads, modal characteristics and responses in frequency range from 1k Hz to 10k Hz are determined for different shell structures. The changes of the modal frequencies and mode shapes are presented with different conical angles, profiles, boundary conditions, and material constants. In analyzing thicker conical shells, shear along the thickness direction is considered based on the first-order shear deformation. The finite element analysis of the shell structures is achieved using the commercial code MSC NASTRAN. Experiments have been performed to verify the accuracy of the theoretical predictions. The effects of material properties on the behaviors of the shell structures have also been studied. It has been found composite conical shells have different behaviors from the isotropic ones. Both theoretical and experimental results on isotropic and composite conical shells are given for comparison.
陳家誠. "Vibration Measurement and Suppression for Scanner Structure". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/09873025694305635913.
Pełny tekst źródła國立成功大學
航空太空工程學系
87
The subject of this thesis is to study the noise stimulated by the structure when the scanner is under operation,and adopting rubber cushion to eliminate the amount of noise. We use six models with different structural conditions to test,and do the experiments to analysis the vibrations resulted from the structure and the air in the scanner respectively,in order to find the source of noise from vibration. We use Structural Dynamics Modification (SDM) to predict the influence of structure vibration by adding rubber with different materials.
YEN-CHIN, CHIANG, i 江彥瑾. "Using Optic Fiber Sensor in Structure Vibration Control". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/32884822327786971669.
Pełny tekst źródła國立臺灣大學
應用力學研究所
82
We present experimental methods for practical implementati -onof few-mode cycle-core sensora. Techniques for desenstizing the lead-in and lead-out fibers are descussed and resuults of a vibration sensors embedded in a graphite-epoxy composite are pr- sented. A scheme using a single mide fiber as the lead-out fiber is successfully impemented. Detection techniques for few- mode fibersensors are reviewed and a novel fringe-counting method to unambiguously detect the amplitude and direction of dynamic str- ain is reported for the first time.
Yu-ShengLu i 呂毓笙. "Vibration Control of Compliant Structure Using Acceleration Feedback". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/95769534796384877843.
Pełny tekst źródła國立成功大學
機械工程學系
102
Automatic optical inspection (AOI) systems adapted on a movable gantry have been widely used in modern large area inspection tasks. The performance of motion control directly affects the accuracy and perhaps the yield of the entire process. To maximize process yield, the gantry should maneuver as fast as possible in order to maximize the throughput. However, this action will generate significant motion-induced vibration that excites the flexible modes of the systems, which may increase the settling time and reduce the inspection efficiency. As a result, a trade-off exists between the speed of movement and the achieved settling time. An alternative approach is to mount AOIs on a controllable stage and to eliminate the relative vibration between the AOI and the corresponding object to be inspected. By this approach, the effective bandwidth can be improved. However, to realize this concept, conventional position sensors cannot be used due to lacks of an absolute reference. An alternative solution is to use accelerometer for providing relative displacement by integrating the measurable accelerations. This solution brings potentially two problems: first, the possible drifting of low frequency signals and second, a re-design of feedback control scheme. By experiments, we successfully develop the anti-drift integrator, which combines two second-order Sallen-Keys high-pass filters and original model of hardware integrator for enhancing the drifting rejection. Otherwise, three controllers of acceleration feedback was designed to enhance the vibration of double clam beam test platform, Nevertheless, through detail step and sinusoidal tests simulation and experimental correlations and interactions, these three controllers have been successfully implemented.In the study, we have realized the integration of acceleration feedback controller and the model of anti-drift integrator for suppressing low frequency drifting by combining of the models of the hardware integrator and two Sallen-Key high-pass filters.. Second, by both simulation and experimental investigation, the acceleration feedback controllers have gotten less effect than the displacement feedback controllers. Although this study was motivated by the needs of AOI vibration control, it is not limited in this application only. The methodology proposed can be used in other applications related to precision positioning control using inertial sensor, such as active vibration control in precision semiconductor processing equipment.
Kang, Po Shyang, i 康博翔. "The hybrid control for vibration of equipment-structure". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/48461673694967982313.
Pełny tekst źródła國立中央大學
土木工程研究所
82
The dynamic response behavior of equipment-structures controlled by a hybrid control system is studied in this research.The hybrid control system used in this studied is constituted by the passive resilient-friction base isolators (RFBI) and the active actuator.Dynamic responses of equipment- structure installed on the floor are analyzed by using the floor response spectrum approach.For passive control system, the stiffness and friction coefficients of RFBI system dominate the controlled effectiveness of the base isolators.To reduce the relative displacement of isolators, the active actuator is used for which the control force is determined by using the classical optimal closed-loop control law. In order to gain the desired objective, the active actuator is designed to contribute damping force only. Thus, the performance weighting matrix, Q, of active actuator has been derived in this report to obtain the desired system damping ratio when the hybrid control system is used.The performance of the hybrid control system is presented in the form of response spectra.Parameters studied in this report are friction coefficient of RFBI system and coefficients of the performance weighting matrix, Q. Numerical results have shown that, although, the RFBI system can reduce the dynamic responses of equipment-structure very effectively.The hybrid control system can provide much better results than the RFBI system alone.