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1
Huang, Chiung-shiann. "Singularities in plate vibration problems /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487688507503742.
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Rosen, Oren. "Sturm-Liouville extensions : applications in plate vibration /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
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Bercin, A. N. "High frequency vibration analysis of plate structures." Thesis, Cranfield University, 1993. http://dspace.lib.cranfield.ac.uk/handle/1826/10030.
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Noise and vibration are important design issues for many types of vehicles such as ships, cars, and aeroplanes. Structure borne sound, which may be of relatively high frequency, usually emanates from an engine or some other type of localised source and propagates through the vehicle. Excessive vibration levels, and thus structural damage, may occur while structural acoustic interactions may lead to unacceptable interior noise. In the analysis of energy transmission between plate structures, it is common practice to consider only bending modes (or waves) of the structure. However if the concern is with high frequency vibration analysis, then due allowance may need to be made for the presence of inplane shear and longitudinal modes. Due to the infeasibility of the industry standard technique, the Finite Element Method, at high frequencies, almost all of the studies that have investigated the importance of in-plane energy transmission have used Statistical Energy Analysis (SEA). In this study an existing dynamic stiffness method is extended to include in-plane effects, and used as a benchmark against which SEA is assessed. Additionally the Wave Intensity Analysis (WIA) technique, which is an improved form of SEA, is extended to in-plane vibrations, and used to identify some of the reasons for the poor performance of SEA in certain applications. All three methods are applied to a wide range of plate structures within the frequency range of 600 Hz to 20 kHz. While the response levels as predicted by the WIA are generally quite close to exact results, it has been found that although all of the requirements which are usually postulated for the successful application of SEA are fulfilled, SEA severely underpredicts the energy transmission in large structures because of the diffuse wave field assumption. It is also shown that the exclusion of in-plane modes may lead to sizeable errors in energy predictions unless the structure is very simple.
4
Hanna, Nagy F. "Thick plate theories, with applications to vibration /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487683049374286.
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Robu, Bogdan. "Active vibration control of a fluid/plate system." Phd thesis, Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1103/.
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Cette thèse s’intéresse au problème du contrôle actif des vibrations structurelles d’une aile d’avion induites par le ballottement du carburant dans les réservoirs qu’elle contient. L'étude proposée ici est concentrée sur l'analyse d'un dispositif expérimental composé d'une longue plaque rectangulaire en aluminium équipée d'actionneurs et de capteurs piézoélectriques et d'un réservoir cylindrique. La difficulté principale réside dans le couplage complexe entre les modes de vibration de l’aile et les modes de ballottement du liquide. Un modèle de ce dispositif à l’aide d’équations aux dérivées partielles est tout d’abord construit. Ce modèle de dimension infinie couple une équation des plaques avec l'équation de Bernoulli pour le mouvement du fluide dans le réservoir. En analysant la contribution énergétique des modes, une approximation en dimension finie, de type espace d'état est alors construite. Après une méthode de recalage fréquentiel du modèle, un contrôle est réalisé en utilisant dans un premier temps une méthode par placement de pôle et dans un deuxième temps, la théorie de la commande robuste H-infini. La dimension du modèle et les performances demandées imposent le calcul d’un contrôleur H-infini d'ordre réduit, conçu en utilisant la librairie HIFOO 2. 0 et testé sur le dispositif expérimental pour différents niveaux de remplissage. Finalement, le problème de la correction simultanée avec un correcteur HIFOO d'ordre réduit est aussi analysé<br>We 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
6
Zahn, Michael L. "Flow-induced vibration of a single flexible cylinder in a normal triangular array." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55656.
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Jane, Kuo Chang. "Buckling, postbuckling deformation and vibration of a delaminated plate." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19975.
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Md, Salleh Salihatun. "Active intelligent control of vibration of flexible plate structures." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538085.
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Vergeer, Pieter. "Vibration isolation of dimple plate heat exchangers / Pieter Vergeer." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8455.
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Dimple plate heat exchangers are a new type of welded compact plate
heat exchangers. The dimple plates increase the turbulence of the fluid
flowing over the plate, increasing the efficiency of the heat exchanger
without increasing pressure drop over the heat exchanger. The compact
design of the heat exchanger makes it possible to install the heat
exchanger at the top of condenser columns, reducing the footprint area
of the column by replacing standard shell and tube condensers at the
foot of the column.
After the implementation of these condensers in 2008, Sasol
experienced failures of 12 column-top dimple plate condensers in unit
300. In these cases damage was observed at the weld between the
plates and the bottom header. One possible reason for the damage was
vibration caused by the flow over the dimple plates.
The characteristics of flow-induced vibrations in dimple plate heat
exchangers were studied in the scientific literature. It was, however,
found that although the effect of dimples on channel walls had been wellresearched,
the fluid-elastic vibration of the bluff body containing the
dimples had not been sufficiently studied. A simple aerodynamic model
was constructed to determine the characteristics of the combination of
vibration caused by the bluff body (plate) and the flow over the dimples
on the plate. The experiment showed the generation of two flow-induced
vibration amplitudes.
The structure of the heat exchanger was modelled by using mass,
stiffness and damping elements. With certain assumptions the model
was reduced to a two degrees of freedom system that simulated the
most prominent vibration direction. This model was used to simulate the
effect of design changes to the response of the structure to a range of
forcing frequencies. An experimental model of the column-top condensers was constructed
and the response due to different vibration frequencies was measured.
The measured results were compared with the theoretically predicted
values for cases with the current design and the cases where the
vibration-control concept was implemented. This validated the theoretical
model and the mathematical simulation as a tool to design vibrationcontrol
systems for real heat exchangers.
With the replacement of the very stiff mounts that are used in current
designs with soft rubber mounts, the dynamic forces on the internal
plates was reduced by up to 97.8% for certain forcing frequencies. The
deflection of the internal plates is a main cause of stress in the plates
and, more importantly, the weld fillets connecting the bottom of the plates
to a common header. This repeated stress can easily cause fatigue
failure in the welds. By therefore reducing the amplitude of vibration of
the heat exchangers, the onset of fatigue failure will be substantially
delayed, increasing the reliable lifetime of the column-top condenser.
This concept is not only limited to dimple plate heat exchangers. The
oscillating stress in any internal component can, therefore, be reduced
by isolating the whole system with soft rubber mounts of a determined
stiffness and layout.<br>Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012
10
McHale, Kimberley Paige Perry. "Inequalities for vibration and buckling of a clamped plate /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9842551.
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Julai, Sabariah. "Nature-inspired algorithms for vibration control of flexible plate structures." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531231.
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Liu, Shin-Hwa. "In-plane and flexural vibration in built-up plate structures." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243073.
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Sors, Thomas Christopher. "Active structural acoustic control of sound transmission through a plate." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326822.
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Chattopadhyay, Arka Prabha. "Free and Forced Vibration of Linearly Elastic and St. Venant-Kirchhoff Plates using the Third Order Shear and Normal Deformable Theory." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102661.
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Employing the Finite Element Method (FEM), we numerically study three problems involving free and forced vibrations of linearly and nonlinearly elastic plates with a third order shear and normal deformable theory (TSNDT) and the three dimensional (3D) elasticity theory. We used the commercial software ABAQUS for analyzing 3D deformations, and an in-house developed and verified software for solving the plate theory equations.
In the first problem, we consider trapezoidal load-time pulses with linearly increasing and affinely decreasing loads of total durations equal to integer multiples of the time period of the first bending mode of vibration of a plate. For arbitrary spatial distributions of loads applied to monolithic and laminated orthotropic plates, we show that plates' vibrations become miniscule after the load is removed. We call this phenomenon as vibration attenuation. It is independent of the dwell time during which the load is a constant. We hypothesize that plates exhibit this phenomenon because nearly all of plate's strain energy is due to deformations corresponding to the fundamental bending mode of vibration. Thus taking the 1st bending mode shape of the plate vibration as the basis function, we reduce the problem to that of solving a single second-order ordinary differential equation. We show that this reduced-order model gives excellent results for monolithic and composite plates subjected to different loads.
Rectangular plates studied in the 2nd problem have points on either one or two normals to their midsurface constrained from translating in all three directions. We find that deformations corresponding to several modes of vibration are annulled in a region of the plate divided by a plane through the constraining points; this phenomenon is termed mode localization. New results include: (i) the localization of both in-plane and out-of-plane modes of vibration, (ii) increase in the mode localization intensity with an increase in the length/width ratio of a rectangular plate, (iii) change in the mode localization characteristics with the fiber orientation angle in unidirectional fiber- reinforced laminae, (iv) mode localization due to points on two normals constrained, and (iv) the exchange of energy during forced harmonic vibrations between two regions separated by the line of nearly stationary points that results in a beating-like phenomenon in a sub-region of the plate. This technique can help design a structure with vibrations limited to its small sub-region, and harvesting energy of vibrations of the sub-region.
In the third problem, we study finite transient deformations of rectangular plates using the TSNDT. The mathematical model includes all geometric and material nonlinearities. We compare the results of linear and nonlinear TSNDT FEM with the corresponding 3D FEM results from ABAQUS and note that the TSNDT is capable of predicting reasonably accurate results of displacements and in-plane stresses. However, the errors in computing transverse stresses are larger and the use of a two point stress recovery scheme improves their accuracy. We delineate the effects of nonlinearities by comparing results from the linear and the nonlinear theories. We observe that the linear theory over-predicts the deformations of a plate as compared to those obtained with the inclusion of geometric and material nonlinearities. We hypothesize that this is an effect of stiffening of the material due to the nonlinearity, analogous to the strain hardening phenomenon in plasticity. Based on this observation, we propose that the consideration of nonlinearities is essential in modeling plates undergoing large deformations as linear model over-predicts the deformation resulting in conservative design criteria. We also notice that unlike linear elastic plate bending, the neutral surface of a nonlinearly elastic bending plate, defined as the plane unstretched after the deformation, does not coincide with the mid-surface of the plate. Due to this effect, use of nonlinear models may be of useful in design of sandwich structures where a soft core near the mid-surface will be subjected to large in-plane stresses.<br>Doctor of Philosophy
15
Marcotte, Pierre. "A Study of Distributed Active Vibration Absorbers (DAVA)." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28897.
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DAVAs are distributed active and passive devices that can be numerically modelled to provide optimum control of low frequency (< 1000 Hz) mean square velocity and sound power radiation. A numerical model of a multi-DAVA system was developed using the Rayleigh-Ritz method coupled to a hierarchical finite element set (p-method).
The numerical model was validated and used to optimize DAVA configurations using lightweight treatments (< 10 % the weight of the base plate weight). The optimizations were performed using genetic algorithms implemented in parallel. They were used to minimize, either passively or actively, the mean square velocity and sound power radiation of different plates having arbitrary boundary conditions (free, simply supported or clamped). Some optimization were also
used to determine the optimum number of DAVAs needed, as well as to compare DAVA attenuations with attenuations obtained from optimum Active Constraining Layer Damping (ACLD) treatments. Preliminary results on the passive minimization of the mean square velocity of a simply supported plate with three devices showed that DAVA treatments produce better attenuations than ACLD treatments in the frequency range of interest [2-1000 Hz], and these increased attenuations were due in part to the better capabilities of DAVA treatments to tackle the plate first bending modes. Apart from the free plate, which showed anyway a very low baseline sound transmission,
excellent attenuations were obtained both passively and actively for minimizing the mean square velocity and sound power radiation of the simply supported and clamped plates.
Following, numerical studies of a DAVA treatment around the optimum solution showed that changing the DAVA top plate stiffness resulted in decreased attenuation, while increasing the DAVA foam layer loss factor increased the attenuation, and decreasing the foam loss factor resulted in decreased attenuation. Finally, by varying the area of the single optimum DAVA that passively minimizes the sound power of the plate, it has been shown that both smaller/lighter and larger/heavier DAVA treatments lead to decreased passive attenuation upon the optimum single DAVA
passive solution.
Finally, experimental results have further validated the DAVA numerical model, and DAVA treatments have shown excellent passive and active experimental attenuations over various flexible plate structures.<br>Ph. D.
16
Ismail, Rainah. "Vibration analysis of a plate with an arbitrarily orientated surface crack." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4002/.
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This research presents a vibration analysis for a thin isotropic plate containing an arbitrarily orientated surface crack. The work has been motivated by the well known applicability of various vibrational techniques for structural damage detection in which the detection and localisation of damage to thin plate structures at the earliest stage of development can optimise subsystem performance and assure a safer life, and is intended to be an enhancement to previous work on cracked plates for which the orientation of the crack angle was not included. The novelty of this research activity has been in the assimilation of a significantly enhanced crack model within the analytical model of the plate, in modal space, and taking the form of a specialised Duffing equation. The governing equation of motion of the plate model with enhanced crack modelling is proposed to represent the vibrational response of the plate and is based on classical plate theory into which a developed crack model has been assimilated. The formulation of the angled crack is based on a simplified line-spring model, and the cracked plate is subjected to transverse harmonic excitation with arbitrarily chosen boundary conditions. In addition, the nonlinear behaviour of the cracked plate model is investigated analytically from the amplitude-frequency equation by use of the multiple scales perturbation method. For both cracked square and rectangular plate models, the influence of the boundary conditions, the crack orientation angle, crack length, and location of the point load is demonstrated. It is found that the vibration characteristics and nonlinear characteristics of the cracked plate structure can be greatly affected by the orientation of the crack in the plate. The dynamics and stability of the cracked plate model are also examined numerically using dynamical systems tools for representing the behaviour of this system for a range of parameters. Finally the validity of the developed model is shown through comparison of the results with experimental work and finite element analysis in order to corroborate the effect of crack length and crack orientation angle on the modal parameters, as predicted by the analysis. The results show excellent predictive agreement and it can be seen that the new analytical model could constitute a useful tool for subsequent investigation into the development of damage detection methodologies for generalised plate structures.
17
Boennen, Dennis. "Analytical beam and annular plate models for automotive disc brake vibration." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/34130.
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Research in brake squeal has been conducted for over fifty years in many different areas and still it is not completely understood. Experimental testing is very time consuming, therefore, there is a need for the development of an analytical model to simulate the test results prior to the prototype stage has arisen in order to gain a deeper understanding of the physics of the system. In this thesis analytical beam and annular plate models in order to investigate the vibrational behaviour of an automotive brake discs are presented and compared to experimental measurements.
18
Ashour, Osama Naim. "Nonlinear Control of Plate Vibrations." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/26266.
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A nonlinear active vibration absorber to control the vibrations of plates is investigated. The absorber is based on the saturation phenomenon associated with dynamical systems with quadratic nonlinearities and a two-to-one internal resonance. The technique is implemented by coupling a second-order controller with the plate's response through a sensor and an actuator. Energy is exchanged between the primary structure and the controller and, near resonance, the plate's response saturates to a small value.
Numerical as well as experimental results are presented for a cantilever rectangular plate. For numerical studies, finite-element methods as well as modal analysis are implemented. The commercially available software ABAQUS is used in the finite-element analysis together with a user-provided subroutine to model the controller. For the experimental studies, the plate is excited using a dynamic shaker. Strain gages are used as sensors, while piezoelectric ceramic patches are used as actuators. The control technique is implemented using a dSPACE digital signal processing board and a modeling software (SIMULINK). Both numerical and experimental results show that the control strategy is very efficient.
A numerical study is conducted to optimize the location of the actuators on the structure to maximize its controllability. In this regard, the control gain is maximized for the PZT actuators. Furthermore, a more general method is introduced that is based on a global measure of controllability for linear systems.
Finally, the control strategy is made adaptive by incorporating an efficient frequency-measurement technique. This is validated by successfully testing the control strategy for a non-conventional problem, where nonlinear effects hinder the application of the non-adaptive controller.<br>Ph. D.
19
Lin, Tian Ran. "Vibration of finite coupled structures, with applications to ship structures." University of Western Australia. School of Mechanical Engineering, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0093.
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[Truncated abstract] Shipbuilding is fast becoming a priority industry in Australia. With increasing demands to build fast vessels of lighter weight, shipbuilders are more concerned with noise and vibration problems in ships than ever. The objective of this thesis is to study the vibration response of coupled structures, in the hope that the study may shed some light in understanding the general features of ship vibration. An important feature characterizing the vibration in complex structures is the input mobility, as it describes the capacity of structures in accepting vibration energy from sources. The input mobilities of finite ribbed plate and plate/plate coupled structures are investigated analytically and experimentally in this study. It is shown that the input mobility of a finite ribbed plate is bounded by the input mobilities of the uncoupled plate and beam(s) that form the ribbed plate and is dependent upon the distance between the source location and the stiffened beam(s). Off-neutral axis loading on the beam (point force applied on the beam but away from the beam’s neutral axis) affects the input power, kinetic energy distribution in the component plates of the ribbed plate and energy flow into the plates from the beam under direct excitation ... solutions were then used to examine the validity of statistical energy analysis (SEA) in the prediction of vibration response of an L-shaped plate due to deterministic force excitations. It was found that SEA can be utilized to predict the frequency averaged vibration response and energy flow of L-shaped plates under deterministic force (moment) excitations providing that the source location is more than a quarter of wavelength away from the plate edges. Furthermore, a simple experimental method was developed in this study to evaluate the frequency dependent stiffness and damping of rubber mounts by impact test. Finally, analytical methods developed in this study were applied in the prediction of vibration response of a ship structure. It was found that input mobilities of ship hull structures due to machinery excitations are governed by the stiffness of the supporting structure to which the engine is mounted. Their frequency averaged values can be estimated from those of the mounting structure of finite or infinite extents. It was also shown that wave propagation in ship hull structures at low frequencies could be attenuated by irregularities imposed to the periodic locations of the ship frames. The vibration at higher frequencies could be controlled by modifications of the supporting structure.
20
Rubenstein, Stephen P. "An experiment in state-space vibration control of steady disturbances on a simply-supported plate." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-03172010-020629/.
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Chu, Pearl. "Nonaxisymmetric radiation patterns of a vibrating elastic plate." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17902.
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Ullah, Israr. "Vibration-based structural health monitoring of composite structures." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/vibrationbased-structural-health-monitoring-of-composite-structures(f21abb03-5b46-4640-9447-0552d5e0c7d6).html.
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Composite materials are in use in several applications, for example, aircraft structural components, because of their light weight and high strength. However the delamination which is one of the serious defects often develops and propagates due to vibration during the service of the structure. The presence of this defect warrants the design life of the structure and the safety. Hence the presence of such defect has to be detected in time to plan the remedial action well in advance. There are a number of methods in the literature for damage detection. They are either 'baseline free/reference free method' or using the data from the healthy structure for damage detection. However very limited vibration-based methods are available in the literature for delamination detection in composite structures. Many of these methods are just simulated studies without experimental validation. Grossly 2 kinds of the approaches have been suggested in the literature, one related to low frequency methods and other high frequency methods. In low frequency approaches, the change in the modal parameters, curvatures, etc. is compared with the healthy structure as the reference, however in the high frequency approaches, excitation of structures at higher modes of the order of few kHz or more needed with distributed sensors to map the deflection for identification of delamination. Use of high frequency methods imposes the limitations on the use of the conventional electromagnetic shaker and vibration sensors, whereas the low frequency methods may not be feasible for practical purpose because it often requires data from the healthy state which may not be available for old structures. Hence the objective of this research is to develop a novel reference-free method which can just use the vibration responses at a few lower modes using a conventional shaker and vibration sensors (accelerometers/laser vibrometers). It is believed that the delaminated layers will interact nonlinearly when excited externally. Hence this mechanism has been utilised in the numerical simulations and the experiments on the healthy and delaminated composite plates. Two methods have been developed here - first method can quickly identify the presence of the delamination when excited at just few lower modes and other method identify the location once the presence of the delamination is confirmed. In the first approach an averaged normalised RMS has been suggested and experimentally validated for this purpose. Latter the vibration data have then been analysed further to identify the location of delamination and its size. Initially, the measured acceleration responses from the composite plates have been differentiated twice to amplify the nonlinear interaction clearly in case of delaminated plate and then kurtosis was calculated at each measured location to identify the delamination location. The method has further been simplified by just using the harmonics in the measured responses to identify the location. The thesis presents the process of the development of the novel methods, details of analysis, observations and results.
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Chantalakhana, Chak. "Model-based control of plate vibrations using active constrained layer damping." Thesis, University of Sheffield, 2000. http://etheses.whiterose.ac.uk/14796/.
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In this thesis, the author presents a numerical and experimental study of the application of active constrained layer damping to a clamped-clamped plate. Piezoelectric actuators with modal controllers are used to improve the performance of vibration suppression from the passive constrained layer damping treatment. Surface damping treatments are often effective at suppressing higher frequency vibrations in thin-walled structures such as beams, plates and shells. However, the effective suppression of lower frequency modes usually requires the additional of an active vibration control scheme to augment the passive treatment. Advances in the technologies associated with so-called smart materials are dramatically reducing the cost, weight and complexity of active structural control and make it feasible to consider active schemes in an increasing number of applications. Specifically, a passive constrained layer damping treatment is enhanced with an active scheme employing a piezoceramic (PZT) patch as the actuator. Starting with an established finite element formulation it is shown how model updating and model reduction are required to produce a low-order state-space model which can be used as the basis for active control. The effectiveness of the formulation is then demonstrated in a numerical study. Finally, in the description of the experimental study it is shown how modes in the frequency range from 0 to 600 Hz are effectively suppressed: the two lowest modes (bending and torsional) through active control, the higher modes (around ten in number) by the passive constrained damping layer. The study'S original contribution lies in the experimental demonstration that given a sufficiently accurate model of the plate and passive constrained damping layer, together with a suitable active feedback control algorithm, spillover effects are not significant even when using a single sensor and single actuator. The experimental traces show, in some instances, minor effects due to spillover. However, it can be concluded that the presence of the passive layer introduces sufficient damping into the residual modes to avoid any major problems when using only the minimum amount of active control hardware.
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Jeffers, Ann E. "Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/36299.
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The purpose of this research is to analyze a new type of vibration isolator consisting of two pre-bent struts which are clamped at both ends and intermediately bonded with a viscoelastic filler. The proposed isolation device has the ability to support a relatively large static load with little deflection and offers a low axial resistance under dynamic excitation, making it ideal for isolating vertical vibrations. In this research, four of these vibration isolators are used to support a rigid, square plate. The symmetric case is analyzed first. Then the plate has a center of mass which is located at some distance from the geometric center of the plate. When the system is subjected to vertical harmonic base excitations, this eccentric weight introduces rotational as well as vertical motions of the plate. This research will investigate the effects of various eccentricities on the efficiency of the vibration isolators in the configuration described.
The displacement transmissibility will be the measure of the isolators' effectiveness at mitigating vibrations transmitted from the base to the rigid plate. For each case, the nonlinear equilibrium equations and the governing equations of motion for small vibrations about equilibrium are numerically solved, and the transmissibility is calculated and plotted over a wide range of frequencies. These plots are used to recognize ranges of frequencies for which isolation is achieved and frequencies at which resonance occurs in the system. At the resonant frequencies, the physical behavior of the system is analyzed to determine the types of vibration modes which occur in the system. A free vibration analysis is also performed to obtain a better understanding of resonances in the system.<br>Master of Science
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Lee, Yong Keat. "Active vibration control of a piezoelectric laminate plate using spatial control approach." Title page, abstract and table of contents only, 2005. http://hdl.handle.net/2440/37711.
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This thesis represents the work that has been done by the author during his Master of Engineering Science candidature in the area of vibration control of flexible structures at the School of Mechanical Engineering, The University of Adelaide, between March 2003 and June 2004. The aim of this research is to further extend the application of the Spatial Control Approach for two-dimensional flexible structures for attenuating global structural vibration with the possible implication of reduction in noise radiation. The research was concentrated on a simply supported thin flexible plate, using piezoelectric ceramic materials as actuators and sensors. In this work, active controllers were designed for the purpose of controlling only the first five vibration modes (0-500Hz) of the plate. A spatial controller was designed to minimize the total energy of the spatially distributed signal, which is reflected by the spatial H2 norm of the transfer function from the disturbance signal to the vibration output at every point over the plate. This approach ensures the vibration contributed by all the in bandwidth (0-500 Hz) vibration modes is minimized, and hence is capable of minimizing vibration throughout the entire plate. Within the control framework, two cases were considered here; the case when the prior knowledge of the incoming disturbance in terms of reference signal is vailable and the case when it is not available. For the case when the reference signal is available, spatial feedforward controller was designed; whereas for the case when the reference signal is not available, spatial feedback controller was designed to attenuate the global disturbance. The effectiveness of spatial controllers was then compared with that of the standard point-wise controllers numerically and experimentally. The experimental results were found to reflect the numerical results, and the results demonstrated that spatial controllers are able to reduce the energy transfer from the disturbance to the structural output across the plate in a more uniform way than the point-wise controllers. The research work has demonstrated that spatial controller managed to minimize the global plate vibrations and noise radiation that were due to the first five modes.<br>Thesis (M.Eng.Sc.)--School of Mechanical Engineering, 2005.
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Zheng, Dingyang. "Vibration and stability analysis of plate-type structures under moving loads by analytical and numerical methods /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20933320.
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Tan, Su-Ting, and 譚夙婷. "Application of Triangular Plate Added Damping and Stiffness Devices to the Vibration Attenuation of Buildings." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/723486.
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碩士<br>國立成功大學<br>土木工程學系碩博士班<br>92<br>The methods of the earthquake resistance ability in structure are raised with the developments of various kinds of structure control technology. Except the general tenacity design, the damping device or earthquake resistance system is added in structure to consume or reduce the energy that produces by earthquake. The application of energy consumption technology is used in the earthquake resistance of structure and is regarded as an effective method gradually. When the concept of energy consumption device is proposed, the relative researches are expanded in all respects and various kinds of damper devices are developed. There are no specific conclusions to all kinds of damper devices that can reach the best effect of earthquake attenuation for the building. The design of adding damper devices is needed to investigate further.
This research studies the Triangular Plate Added Damping and stiffness Device (TPADS). First, we carry on the experiments to probe into the energy consumption behavior of TPADS, and the ability consumption of TPADS is verified according to the stable hysteresis loop. Second, finite element analyses and the theoretical solution are used to compare the mechanics behavior. Finally, the nonlinear structure analysis is performed to investigate the efficiency of TPADS and diagonal brace to buildings. The result can be provided for some other persons as an effective basis to design the buildings that need adding the energy consumption devices.
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Hsu, Wen-Chang, and 許文昌. "Investigation of Triangular Plate Element." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/26367660935963773945.
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CHEN, JUN-CHENG, and 陳俊成. "The study of various triangular plate elements." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/97953536811177584077.
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Lin, Shih-Po, and 林詩渤. "A Simple Triangular Plate Element For Nonlinear Analysis." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/67726296366318510957.
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Chou, Chung-Che, and 周中哲. "Plastic Models for Steel Triangular Plate Energy Absorbers." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/60109095840058009817.
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Chang, Kao-Liang, and 張國亮. "Vibration Analysis of Plates by Plate-Type Dynamic Vibration." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/88008829251486836923.
Full textAbstract:
碩士<br>國立中央大學<br>機械工程學系<br>86<br>In this paper,a plate-type dynamic vibration absorber is
presented for behaviorof vibration of mainplate under random
excitation and impact excitation,which boundary condition is
simple supported.This system consists of a dynamic absorbing
plate under free boundary condition as the main plate and with
uniformly distributed connecting springs and dampersbetween the
main and dynamic absorbing plates.By way of defection of mean
squareresponse minimum we can obtain optimum frequency ratio,
damper ratio,and positionserveral parameters.At lest we use
method of steepest decent when main plate underrandom excitation
and impact excitation progress in dynamic absorbers analysisand
design.The numerical calculations demonstrate the effectiveness
the plate-typedynamic absorbers and it can applies for industry.
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Lin, Chang-Hsi, and 林章熹. "Vibration Analysis of Triangular Spatial Beam-Like Lattice Girders." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/15194027088680494307.
Full textAbstract:
碩士<br>國立成功大學<br>造船工程學系<br>85<br>A modify structural-simplification-method(SSM) that can
achieve reasonableaccuracy for ssolving the vibration problem of
triangular spatial beam-like lattice girders was studied. In
corporated with the simplification method, an optimum transfer
matrix for arriving at better accuracy in natural frequencieswas
presented. By modified the diagonal coefficients rkk of the
transfer matrix [r2] & [r5],the better accuracy in natural
frequencies can be achieved. An ptimization method was used to
modify the former coefficients rkk with its as active
variables and relative difference between natural frequencies
solving by FEM and SSM as a objective function. Numerical
results show that the SSM methods with an optimum transfer
matrix is suitable for the vibration analysis of the triangular
X-braced, Pratt or Warren spatial beam-like latticegirders. For
a 20-bay spatial X-braced lattice girder with rigid joints, the
SSM method needs comupter time less than 1.7% of that required
by the FEM method and achieves an average accuracy higher
than 95% in natural frequencies.
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Kao-Liang, Chang, and 張國亮. "Vibration Analysis of Plates by Plate-Type Dynamic Vibration Absorbers." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/93606596534914299921.
Full textAbstract:
碩士<br>國立中央大學<br>機械工程研究所<br>87<br>esented for behavio
rof vibration of mainplate under random excitation and impact excitation,which
boundary condition is simple supported.This system consists of a dynamic abso
rbing plate under free boundary condition as the main plate and with uniformly
distributed connecting springs and dampersbetween the main and dynamic absorb
ing plates.By way of defection of mean squareresponse minimum we can obtain op
timum frequency ratio,damper ratio,and positionserveral parameters.At lest we
use method of steepest decent when main plate underrandom excitation and impac
t excitation progress in dynamic absorbers analysisand design.The numerical ca
lculations demonstrate the effectiveness the plate-typedynamic absorbers and i
t can applies for industry.
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hu, Wen Chou, and 胡文超. "Vibration of the plate with voids." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/80468088965010191693.
Full textAbstract:
碩士<br>國立中興大學<br>應用數學系<br>85<br>In this paper,a function of static beam under a point load is
used as a shape function of the plate with voids,and Rayleigh-
Ritz method is used to solve thefrequency.In order to solve the
discontinuous rigidity, Extended Dirac function is used.
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Hwang, Jyh shing, and 黃志興. "VIBRATION ANALYSIS OF HEATED COMPOSITE PLATE." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/13047569139061143776.
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Mohanty, Regal. "Vibration Analysis of Cracked Composite Plate." Thesis, 2015. http://ethesis.nitrkl.ac.in/7165/1/Vibration_Mohanty_2015.pdf.
Full textAbstract:
Composite materials are widely used in different arenas such as aircraft, naval and automobiles. Main motive behind that is the distinctive property of weight reduction, which is important for greater speeds, improved payloads and efficient fuel consumption. Various damages like cracks or delamination are inevitable during service period. They may be due to impact load, chemical decay or change in temperature or pressure conditions. It has been experimentally proved that confined damage in a structure causes the reduction in local structural stiffness, resulting in deviations in dynamic performance of the structure. Additional resonance or crack proliferation induce large displacements resulting in the failure of the structure. In this study, efforts have been made to determine the natural frequency of vibration of composite plate in different boundary conditions and the multiple parameters of crack have been varied and the results have been established. The tests on composite plate is done experimentally to find natural frequency using FFT analyser and the results are validated using ANSYS. The work is done with varying crack parameters like depth, length and orientation. The frequency decreases with increase in crack dimensions and decreases with increasing orientations. For different boundary conditions, frequency increases with decreasing degrees of freedom. This will help in designing structures resistant to earthquakes and other disasters, given that the resonance frequency is known earlier. It will help in building a safe structure and will prolong its life for many years.
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Chen, Jyh-Liang, and 陳志良. "The Vibration Analysis of Damped Thin Plate." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/71123680061170916872.
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Liu, Yan Jane. "Development of the MIN-N family of triangular anisoparametric Mindlin plate elements." 2002. http://wwwlib.umi.com/dissertations/fullcit/3057369.
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Su, J. H., and 蘇瑞翔. "Impingement Cooling over a Flat Plate under Vibration." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/83943737518862233600.
Full textAbstract:
碩士<br>國立成功大學<br>航空太空工程學系<br>88<br>Experiments are performed to study the effect of convectived heat transfer when the steady flow impinge on a uniform heated surface which is constant heat flux of the flat plate model. It is static or vibrating parallel to the fluid with variable excition of frequency and amplitude.
Experimentally, linking with source of electric current to thin metal Ti stripes, and they are covered over the plate surface. The oscillation of the plate model is provided by the electric motor and the cam. The range of needed frequency is from 0 to 15 Hz, amplitude is 0.5, 1 and 1.5mm.
The range of Reynolds number for the cross uniform flow is from 1000 to 2750 by small low-speed wind tunnel. The distribution of wall temperatures are measured by the K-Type thermocouples. According to the local and average Nusselt numbers the effect of vibrative frequency and amplitude on heat transfer from flat plate model could be analysis.
Conclude the results, the more higher vibrative frequency the plate model has, the more better heat transfer efficiency on the plate surface it gets, in addition to the stagnation and the near wake region. And the more greater vibrative amplitude the plate model has, the more better heat transfer efficiency on the plate surface it gets, also in addition to the stagnation and the near wake region. In this experiments, if the proportion of distance to model''s surface is more than z/b=8，the convectived heat transfer will be no appreciable change. However, when the z/b=2, the average and stagnation point Nusselt number will be maximum. And there is more better heat transfer efficiency on the surface of plate, when the vibrative amplitude is greater to greater.
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Chen, Yao-Pang, and 陳耀邦. "Free vibration analysis of delaminated sandwich beam-plate." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/03806763448048016618.
Full textAbstract:
碩士<br>國立成功大學<br>航空太空工程學系<br>86<br>Abstract:The effect of delamination on the natural frequency of
a delaminated sandwich beam was investigated by Finite Element
Method. Bending theory of sandwich beams were employed for the
analysis. The deflection due to bending and shear of sandwich
beams were described by a third order polynomial.. The effect of
delamination length, delamination location, thickness ratio of
face to core, boundary condition and material properties were
studied. Results show that beam with longer delamination, the
vibration mode tends to be local.
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Wen-YuLiang and 梁文宇. "Axisymmetric Free Vibration of Transversely Isotropic Circular Plate." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/95425663704912517736.
Full textAbstract:
碩士<br>國立成功大學<br>土木工程學系碩博士班<br>98<br>On the basis of the state space approach, the axisymmetric free vibration of transversely isotropic circular plate is analyzed. The state equation of axisymmetric free vibration of transversely isotropic circular plate is established from three-dimensional basic equations of elasticity in the cylindrical coordinates. By using separation of variables, the components of displacements and stresses are expressed as a superposition of two sets of particular solutions of the state equation with enough coefficients to satisfy arbitrary boundary conditions and determine the frequencies for the free vibration of plate. The results for the transversely isotropic and the isotropic plates are presented, and the latter are compared with those based on the linear shear-deformation Mindlin plate theory.
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Hsu, Ting-Wei, and 許庭瑋. "The vibration analysis of partial electrode piezoelectric plate." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/20653742744967510316.
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碩士<br>國立臺灣大學<br>應用力學研究所<br>95<br>We first discuss the effect of mesa design for QCM system. The energy trapping effect will disappear under the specific geometry of QCM, and we call dropping effect. When this phenomenon occurs, the measurement will generate a lot of frequency drift and decrease the accuracy of QCM.
To avoid the phenomenon of dropping effect, we use finite element method and the numerical method to analyze the approximately geometry and the reasons for dropping effect. Until now, we can not find out the real reasons of dropping effect occurs, but we use the solution of simulations and analytic approaches to find out its regularities and possible sizes.
In the model of dual-electrode QCM, one electrode will have influence on the other during operation, further reducing accuracy. Hence, this thesis is to find out the extent of impact and the corresponding relation to minimize it through the mesa design.
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Huang, Chien-Hang, and 黃健航. "Vibration Analysis of Circular Plate with Radial Crack." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/13520947757655095453.
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碩士<br>中原大學<br>機械工程研究所<br>94<br>ABSTRACT
The analysis of vibration for the simply supported circular plate with an edge crack is presented. The governing equation and displacement function of classical theory is considered in vibration analysis. Using the frequency values of Yuan, Young and Dickinson solved by Rayleigh-Ritz method to fitting a fundamental natural frequency polynomial and curve. The vibration analysis includes free vibration and force vibration. The equations of vibration are reduced to an ordinary differential equation by assuming mode shapes and Galerkin’s procedure. Then compare the error percentage of fundamental natural frequency for different authorities. By using of the Runge-Kutta method, the amplitude for different crack ratios and excited frequency with free vibration and force vibration are determined from the Mathieu equation. The results and diagrams are provided in this study dividedly. One can find that during the vibration of the cracked circular plate, the natural frequency decreases with the crack depth. The unsteady relation of vibration with frequency and amplitude for cracked circular plate is the major accomplishment in this study.
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高金海. "The vibration control of four-point-supported plate." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/33068930337075909872.
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Ravi. "Vibration and Buckling Behaviour of Laminated Composite Plate." Thesis, 2013. http://ethesis.nitrkl.ac.in/5003/1/Vibration_and_Buckling_Behaviour_of_Laminated_Composite_Plate.pdf.
Full textAbstract:
Free vibration and buckling responses of laminated composite plate in the framework of first order shear deformation theory is analysed. The model has been developed in ANSYS using ANSYS parametric design language code. The model has been developed in ANSYS using ANSYS parametric design language code. In this study two shell elements (SHELL181/SHELL281) have been chosen from the ANSYS element library to discretise and obtain the elemental equations. The governing differential eigenvalue equations have been solved using Block-Lanczos algorithm. The solution predicts fundamental natural frequencies and critical buckling load of laminated composite plate. To establish the correctness of the proposed model, a convergence study has been done and the results obtained by using the model are compared with the available published literature. Effect of different parameters such as the thickness ratios, the aspect ratios, the modular ratios and the boundary conditions on the free vibration and buckling behavior of laminated composite plate is discussed.
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Bankar, Suraj Sitaram. "Vibration and Acoustic Analysis of Laminated Composite Plate." Thesis, 2015. http://ethesis.nitrkl.ac.in/7160/1/Vibration_Bankar_2015.pdf.
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Conventional materials such as steel, aluminium etc. are used in industries because of their high strength and stiffness. But composite materials have taken their places because they are giving excellent strength and stiffness with low weight. Currently, many industries such as automobile, aerospace, trains, buildings are using sandwich materials to reduce noise level. These sandwich materials consist of sheets of conventional materials which are bonded by polymers, plastics to reduce vibration and noise. In this study, vibration and acoustic analysis of laminated composite plate are carried out experimentally. Carbon fibre reinforced polymer and glass fibre reinforced polymer plates are used to study low frequency vibration and their effect of surrounding air medium. Combined modes shapes are formed because of resonance of natural frequencies of the structure and acoustic cavity. These combined mode shapes generally occur in low frequency region and possesses both high-order displacement and high-order pressure amplitude. The effect of number of plies and ply angle are investigated on the natural frequency and the pressure amplitude. The finite element simulation model is developed to validate the results obtained from experiment
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Jena, Rini. "Free Vibration and Buckling Analysis of Sandwich Plate." Thesis, 2016. http://ethesis.nitrkl.ac.in/9201/1/2016_MT_RJena.pdf.
Full textAbstract:
The present study deals with the free vibration analysis of a three layered sandwich plate. It consists of a damping layer which is viscoelastic in nature being sandwiched or glued in between two elastic face plates; one being the basic plate at the bottom and another one is the constraining layer at the top. The finite element modeling is based on first order shear deformation theory. The mathematical calculation is done by Finite Element Method in which each layer of the plate is discretized into small elements and by using the governing equations of motion, the static and dynamic characteristics of a sandwich plate like its frequency and its buckling load capacity is determined. Here we have a four-noded sandwich plate element which has seven degrees of freedom at each node in order to have same transverse displacement. The equations of motion are determined by Hamilton’s principle. Then the required validation is done by comparing the results of the theoretical method with those obtained from analysis using ANSYS. The analysis is done by using ANSYS (APDL) software and its natural frequencies and their nodal displacements were found out by taking simply supported end condition on all the four sides of a sandwich plate.
For studying the buckling analysis of plates, a uniaxial compressive load was applied on the edge and the effect of various geometric parameters on critical buckling load was determined. The convergence of buckling load with mesh size was studied .The results obtained were same as the reference values with good accuracy.
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Abhiman, Tompe Umesh. "Vibration Analysis of Nano-Plate Using Nonlocal Elasticity." Thesis, 2016. http://ethesis.nitrkl.ac.in/9298/1/2016_MT_TUAbhiman.pdf.
Full textAbstract:
In last decade, nanoplates were used in various types of industries such as electronics, aircraft, satellite. Gas sensors and flexible electronics are other potential applications. Graphene nano-plate is a transparent conductor it can be used in applications such as touch screens, light panels and solar cells. New types of composite materials based on graphene nano-plate with high strength and light weight could also become interesting for use in aircraft and satellites. These types of the structure are under the different type of loading such as electric loading, aerodynamic loading. Due to these loadings, there will be a vibrations occurs which affects the performance and working life of the nano-plate panel. The fundamental frequency/first mode of vibration is always associated with maximum amplitude and it produces large compression and/or tension which lead to breakdown of the structural component. Therefore, the vibration analysis of nano-plate becomes significant. In this work, the free vibration behavior of the nano-plate is analyzed using nonlocal elasticity theory. The model has been developed using higher order shear deformation theory and discretised through suitable finite element steps. The responses are computed numerically through a customized computer code developed in MATLAB environment. The effect of aspect ratio, size and nonlocal on the frequency response is analyzed in detail.
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Chen, Cheng-Yi, and 陳政憶. "Vibration Reduction of the Formation of Multiple-TMDs on a Vibration Rigid Plate." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75408651947577497013.
Full textAbstract:
碩士<br>淡江大學<br>航空太空工程學系碩士班<br>101<br>This study proposed an economical and effective method of reducing vibration in a rigid-plate mechanism. The prime vibrating mechanism comprised a rigid body plate joined by a cubic nonlinear spring at each of the four corners to simulate a transversal and out-of-plane vibration of the plate. A torsional spring was also attached to simulate the in-plane torsional vibration. Four combinations of multiple TMDs (plate edge lined, plate cross, plate edged box, and plate diagonal lined locations) were attached under the plate. Lagrange’s equation was used to derive the motion of the rigid plates. Vibration reduction effect was studied analytically and numerically following attachment of the TMD at different fixed positions in the system. We employed the method of multiple scales (MOMS) to find the fixed points solutions and the associated frequency responses. The numerical simulation was carried on by the RK-4 method. Both numerical and analytical solutions agreed with each other. The results show that the box or cross combinations of multiple TMDs locations reveal the most effective in reducing the amplitude of vibrations of the plates, when the force was applied on the 1st quadrant or the plate origin