Current Search: Vibrators (x)
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Title

A midfrequency vibration analysis of a Tbeam.

Creator

Fremiot, Thomas., Florida Atlantic University, Cuschieri, Joseph M.

Abstract/Description

This thesis describes a numerical technique for modeling the vibrational behavior of a complex structure in the midfrequency range. The structure is divided into subsystems, and each subsystem is modeled using Finite Elements. The obtained results are then manipulated to model variations in the response due to nominal variations in the structure. Based on a Component Mode Synthesis representation, the calculations lead to a deterministic energy flow model. The model represents the...
Show moreThis thesis describes a numerical technique for modeling the vibrational behavior of a complex structure in the midfrequency range. The structure is divided into subsystems, and each subsystem is modeled using Finite Elements. The obtained results are then manipulated to model variations in the response due to nominal variations in the structure. Based on a Component Mode Synthesis representation, the calculations lead to a deterministic energy flow model. The model represents the deterministic dynamic behavior of the structure for mid frequencies. However, in mid frequencies, the response is sensitive to perturbations in the properties of the structure. An appropriate way to represent those perturbations is to calculate the response of an ensemble of structures. The ensemble is defined in terms of the statistics of the local natural frequencies. A technique combining a Monte Carlo simulation with the Perturbation approach is used to relate the perturbations in the local natural frequencies to the statistics of the energy flow. This combined method is computationally tractable, being several times faster than a full Monte Carlo simulation of the whole global structure.
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Date Issued

2001

PURL

http://purl.flvc.org/fcla/dt/12739

Subject Headings

Concrete beamsVibration, Finite element methods, Monte Carlo method

Format

Document (PDF)


Title

Thrust Response of a VectoredThruster Unmanned Underwater Vehicle.

Creator

Ackermann, Lloyd E. J., von Ellenrieder, Karl, Florida Atlantic University

Abstract/Description

Towing tank/water flume experiments are conducted to characterize the dynamics of a RemotelyPiloted Unmanned Underwater Vehicle (RPUUV) propelled by a vectoredthruster system. Force and torque measurements are used to determine the coefficients of drag, lift, yawmoment and thrust of the vehicle as a function of the vehicle yaw angle and the vectoredthruster rudder angle. Simultaneously, particle Image Velocimetry (PIV) measurements of the propeller inlet flow are also performed to examine...
Show moreTowing tank/water flume experiments are conducted to characterize the dynamics of a RemotelyPiloted Unmanned Underwater Vehicle (RPUUV) propelled by a vectoredthruster system. Force and torque measurements are used to determine the coefficients of drag, lift, yawmoment and thrust of the vehicle as a function of the vehicle yaw angle and the vectoredthruster rudder angle. Simultaneously, particle Image Velocimetry (PIV) measurements of the propeller inlet flow are also performed to examine the variation of flow conditions at the propeller inlet with rudder angle. The tests are conducted at 0.150 rnls, 0.300 rnls, 0.515 rnls and 0.773 rnls. While the measured drag coefficient is slightly higher than predicted by theory at low Reynolds number (1.44 x10^5 and 2.88 x10^5), the hydrodynamic coefficients data are expected to be useful in predicting the response of vehicles in the field. Additionally, the magnitude of the thrust vector varies nonlinearly with rudder angle and for nonzero rudder angles the thrust vector does not point in the same direction as the thruster axis.
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Date Issued

2007

PURL

http://purl.flvc.org/fau/fd/FA00012500

Subject Headings

Naval architecture, Oceanographic submersiblesHydrodynamics, Vibration (Marine engineering)

Format

Document (PDF)


Title

Rainwindinduced cable vibrations in cablestayed bridges.

Creator

Calle, Oscar F., Reddy, Dronnadula V., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering

Abstract/Description

This research is aimed at investigating and analyzing the rainwindinduced cable vibration phenomena experienced in cables of cablestayed bridges and also the countermeasures employed by engineers to mitigate the largeamplitude vibration problem reported by various researchers around the world. In order to investigate the problem of the water rivulet creation at the top of the cable surface, a singledegreeoffreedom (SDOF) analytical model was developed and analyzed. This thesis studies...
Show moreThis research is aimed at investigating and analyzing the rainwindinduced cable vibration phenomena experienced in cables of cablestayed bridges and also the countermeasures employed by engineers to mitigate the largeamplitude vibration problem reported by various researchers around the world. In order to investigate the problem of the water rivulet creation at the top of the cable surface, a singledegreeoffreedom (SDOF) analytical model was developed and analyzed. This thesis studies the aerodynamic instability of cables in cablestayed bridges by doing literature review of a typical insitu test, developing a single degreeoffreedom (SDOF) analytical model, and an ANSYS finite element model. Furthermore, a linear viscous damper that acts as a countermeasure to the large amplitudes of vibration is reported and analyzed. The suppression characteristics and damper effectiveness of such countermeasure are summarized.
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Date Issued

2014

PURL

http://purl.flvc.org/fau/fd/FA00004271, http://purl.flvc.org/fau/fd/FA00004271

Subject Headings

Bridges  Aerodynamics, Bridges  Vibration  Prevention, Cable stayed bridges  Maintenance and repair, Damping (Mechanics), Structural dynamics, Vibration  Mathematical models, Wind resistant design

Format

Document (PDF)


Title

Analysis of blast/explosion resistant reinforced concrete solid slab and TBeam bridges.

Creator

Abdelahad, Firas A., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering

Abstract/Description

This study presents and illustrates a methodology to calculate the capacity of an existing reinforced concrete bridge under a nonconventional blast load due to low and intermediate pressures. ATBlast program is used to calculate the blast loads for known values of charge weight and stand off distance. An excel spreadsheet is generated to calculate ultimate resistance, equivalent elastic stiffness, equivalent elastic deflection, natural period of the beam, the maximum deflection, and the...
Show moreThis study presents and illustrates a methodology to calculate the capacity of an existing reinforced concrete bridge under a nonconventional blast load due to low and intermediate pressures. ATBlast program is used to calculate the blast loads for known values of charge weight and stand off distance. An excel spreadsheet is generated to calculate ultimate resistance, equivalent elastic stiffness, equivalent elastic deflection, natural period of the beam, the maximum deflection, and the maximum rotation in the support for a simple span solid slab and TBeam bridges. The allowable rotation could be taken as to two degrees. Naval Facility Engineering Command (NAVFAC) approach was adopted, where the inputs were material properties, span length, and area of reinforcement. The use of the Fiber Reinforced Polymer for increasing the capacity of an existing bridge is also presented in this study. Parametric studies were carried out to evaluate the performance of the solid slab and TBeam bridges under the assumed blast load.
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Date Issued

2008

PURL

http://purl.flvc.org/fcla/flaent/EN00154040/68_1/98p0132d.pdf, http://purl.flvc.org/FAU/58001

Subject Headings

Concrete beams, Vibration, Bridges, Concrete, Fatigue, Reinforced concrete construction, Bridges, Concrete, Design and construction

Format

Document (PDF)


Title

Dissipation and eddy mixing associated with flow past an underwater turbine.

Creator

Reza, Zaqie, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

The objective of this thesis is to analyze the flow past an ocean current turbine using a finite volume NavierStokes CFD solver. A full 3D RANS approach in a moving reference frame is used to model the flow. By employing periodic boundary conditions, onethird of the flowfield is analyzed and the output is replicated to other sectors. Following validation of the computation with an experimental study, the flow fields and particle paths for the case of uniform and sheared incoming flows...
Show moreThe objective of this thesis is to analyze the flow past an ocean current turbine using a finite volume NavierStokes CFD solver. A full 3D RANS approach in a moving reference frame is used to model the flow. By employing periodic boundary conditions, onethird of the flowfield is analyzed and the output is replicated to other sectors. Following validation of the computation with an experimental study, the flow fields and particle paths for the case of uniform and sheared incoming flows past a generic turbine with various blade pitch angles are evaluated and analyzed. Flow field and wake expansion are visualized. Eddy viscosity effects and its dependence on flow field conditions are investigated.
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Date Issued

2010

PURL

http://purl.flvc.org/FAU/2683537

Subject Headings

Vibration (Aerodynamics), Fine element method, Marine turbines, Mathematical models, Water currents, Forecasting, Computational fluid dynamics

Format

Document (PDF)


Title

Vibration analysis for ocean turbine reliability models.

Creator

Wald, Randall David., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science

Abstract/Description

Submerged turbines which harvest energy from ocean currents are an important potential energy resource, but their harsh and remote environment demands an automated system for machine condition monitoring and prognostic health monitoring (MCM/PHM). For building MCM/PHM models, vibration sensor data is among the most useful (because it can show abnormal behavior which has yet to cause damage) and the most challenging (because due to its waveform nature, frequency bands must be extracted from...
Show moreSubmerged turbines which harvest energy from ocean currents are an important potential energy resource, but their harsh and remote environment demands an automated system for machine condition monitoring and prognostic health monitoring (MCM/PHM). For building MCM/PHM models, vibration sensor data is among the most useful (because it can show abnormal behavior which has yet to cause damage) and the most challenging (because due to its waveform nature, frequency bands must be extracted from the signal). To perform the necessary analysis of the vibration signals, which may arrive rapidly in the form of data streams, we develop three new waveletbased transforms (the Streaming Wavelet Transform, ShortTime Wavelet Packet Decomposition, and Streaming Wavelet Packet Decomposition) and propose modifications to the existing ShortTIme Wavelet Transform. ... The proposed algorithms also create and select frequencyband features which focus on the areas of the signal most important to MCM/PHM, producing only the information necessary for building models (or removing all unnecessary information) so models can run on less powerful hardware. Finally, we demonstrate models which can work in multiple environmental conditions. ... Our results show that many of the transforms give similar results in terms of performance, but their different properties as to time complexity, ability to operate in a fully streaming fashion, and number of generated features may make some more appropriate than others in particular applications, such as when streaming data or hardware limitations are extremely important (e.g., ocean turbine MCM/PHM).
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Date Issued

2012

PURL

http://purl.flvc.org/FAU/3359158

Subject Headings

Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Vibration, Measurement, Stochastic processes

Format

Document (PDF)


Title

Vibration, buckling and impact of carbon nanotubes.

Creator

Pentaras, Demetris., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

Natural frequencies of the double and triplewalled carbon nanotubes are determined exactly and approximately for both types. Approximate solutions are found by using BubnovGalerkin and PetrovGalerkin methods. For the first time explicit expressions are obtained for the natural frequencies of double and triplewalled carbon nanotubes for different combinations of boundary conditions. Comparison of the results with recent studies shows that the above methods constitute quick and effective...
Show moreNatural frequencies of the double and triplewalled carbon nanotubes are determined exactly and approximately for both types. Approximate solutions are found by using BubnovGalerkin and PetrovGalerkin methods. For the first time explicit expressions are obtained for the natural frequencies of double and triplewalled carbon nanotubes for different combinations of boundary conditions. Comparison of the results with recent studies shows that the above methods constitute quick and effective alternative techniques to exact solution for studying the vibration properties of carbon nanotubes. The natural frequencies of the clampedclamped doublewalled carbon nanotubes are obtained; exact solution is provided and compared with the solution reported in the literature. In contrast to earlier investigation, an analytical criterion is derived to establish the behavior of the roots of the characteristic equation. Approximate BubnovGalerkin solution is also obtained to compare natural frequencies at the lower end of the spectrum. Simplified version of the BresseTimoshenko theory that incorporates the shear deformation and the rotary inertia is proposed for free vibration study of doublewalled carbon nanotubes. It is demonstrated that the suggested set yields extremely accurate results for the lower spectrum of doublewalled carbon nanotube. The natural frequencies of doublewalled carbon nanotubes based on simplified versions of Donnell shell theory are also obtained. The buckling behavior of the doublewalled carbon nanotubes under various boundary conditions is studied. First, the case of the simply supported doublewalled carbon nanotubes at both ends is considered which is amenable to exact solution., Then, approximate methods of BubnovGalerkin and PetrovGalerkin are utilized to check the efficacy of these approximations for the simply supported doublewalled carbon nanotubes. Once the extreme accuracy is demonstrated for simply supported conditions, the approximate techniques are applied to two other cases of the boundary conditions, namely to clampedclamped and simply supportedclamped doublewalled carbon nanotubes. For the first time in the literature approximate expression for the buckling loads are reported for these boundary conditions. The dynamic deflection of a singlewalled carbon nanotube under impact loading is analyzed by following a recently study reported on the energy absorption capacity of carbon nanotubes under ballistic impact.
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Date Issued

2009

PURL

http://purl.flvc.org/FAU/186764

Subject Headings

Nanostructured materials, Buckling (Mechanics), Plates (Engineering), Vibration, Mathematical models, Structural analysis

Format

Document (PDF)


Title

Simulation and modeling of flow field around a horizontal axis wind turbine (HAWT) using RANS method.

Creator

Sargsyan, Armen., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

The principal objective of the proposed CFD analysis is to investigate the flow field around a horizontal axis wind turbine rotor and calculate the turbine's power. A full three dimensional computational fluid dynamics method based on Reynolds Averaged Navier Stokes approach was used in this study. The wind turbine has three blades and a rotor diameter of six meters. One third of the wind turbine rotor was modeled by means of 120o periodicity in a moving reference frame system. The power...
Show moreThe principal objective of the proposed CFD analysis is to investigate the flow field around a horizontal axis wind turbine rotor and calculate the turbine's power. A full three dimensional computational fluid dynamics method based on Reynolds Averaged Navier Stokes approach was used in this study. The wind turbine has three blades and a rotor diameter of six meters. One third of the wind turbine rotor was modeled by means of 120o periodicity in a moving reference frame system. The power coefficient curve obtained from the CFD results is compared with experimental data obtained by NREL Phase VI rotor experiment. The numerical result for the power coefficient curve shows close agreement with the experimental data. The simulation results include the velocity distribution, pressure distribution along the flow direction, turbulent wake behind the wind turbine, and the turbine's power. The discussion will also include the effect of wind speed on turbine's power.
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Date Issued

2010

PURL

http://purl.flvc.org/FAU/2979383

Subject Headings

Wind turbines, Aerodynamics, Computer simulation, Fluid dynamics, Computational methods, Vibration (Aerodynamics)

Format

Document (PDF)


Title

Helicopter stability during aggressive maneuvers.

Creator

Mohan, Ranjith., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

The dissertation investigates helicopter trim and stability during level bankangle and diving bankangle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are:...
Show moreThe dissertation investigates helicopter trim and stability during level bankangle and diving bankangle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are: 1) to assess the sensitivity of the trim and stability predictions to the approximations in modeling stall, 2) to correlate the trim predictions with the UH60A flight test data, and 3) to demonstrate the feasibility of routinely using the exact fastFloquet periodic eigenvector method for mode identification in the stability analysis. The UH60A modeling and analysis are performed using the comprehensive code RCAS (Army's Rotorcraft Comprehensive Analysis System). The trim and damping predictions are based on quasisteady stall, ONERAEdlin vi (Equations Differentielles Lineaires) and LeishmanBeddoes dynamic stall models. From the correlation with the test data, the strengths and weaknesses of the trim predictions are presented.
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Date Issued

2012

PURL

http://purl.flvc.org/FAU/3342237

Subject Headings

Helicopters, Aerodynamics, Helicopters, Control systems, Rotors (Helicopters), Aerodynamics, Stability of helicopters, Vibration (Aeronautics), Damping

Format

Document (PDF)


Title

Convex identification and nonlinear random vibration analysis of elastic and viscoelastic structures.

Creator

Fang, Jianjie, Florida Atlantic University, Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

This dissertation deals with the identification of boundary conditions of elastic structures, and nonlinear random vibration analysis of elastic and viscoelastic structures through a new energybased equivalent linearization technique. In the part of convex identification, convex models are utilized to represent the degree of uncertainty in the boundary condition modification. This means that the identification is actually the identification of the convex model to which the actual boundary...
Show moreThis dissertation deals with the identification of boundary conditions of elastic structures, and nonlinear random vibration analysis of elastic and viscoelastic structures through a new energybased equivalent linearization technique. In the part of convex identification, convex models are utilized to represent the degree of uncertainty in the boundary condition modification. This means that the identification is actually the identification of the convex model to which the actual boundary stiffness profile belongs. Two examples are presented to illustrate the application of the method. For the beam example the finite element analysis is performed to evaluate the frequencies of a beam with any specific boundary conditions. For the plate example, the Bolotin's dynamic edge effect method, generalized by Elishakoff, is employed to determine the approximate natural frequencies and normal modes of elastically supported isotropic, uniform rectangular plates. In the part of nonlinear random analysis, first a systematic finite element analysis procedure, based on the element's energy formulation, through conventional stochastic linearization technique, is proposed. The procedure is applicable to a wide range of nonlinear random vibration problem as long as element's energy formulations are presented. Secondly, the new energybased stochastic linearization method in finite element analysis setting is developed to improve the conventional stochastic linearization technique. The entire formulation is produced in detail for the first time. The theory is applied to beam problem subjected to spacewise and timewise white noise excitations. Finally, the new energybased stochastic linearization technique is applied to treat nonlinear vibration problems of viscoelastic beams.
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Date Issued

1996

PURL

http://purl.flvc.org/fcla/dt/12467

Subject Headings

Elasticity, Viscoelasticity, Structural dynamicsMathematical models, VibrationMathematical models

Format

Document (PDF)


Title

Experimental determination of motioninduced force coefficients of longspan bridge models in a water channel.

Creator

Wei, Li., Florida Atlantic University, Su, TsungChow, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

Wind loads on a bridge may be classified into two types: the buffeting loads and the selfexcited loads. The research reported in this thesis is concerned with experimental determination of the selfexcited loads in the frequency domain, in particular, their nondimensional coefficients, called flutter derivatives. The experiments were conducted in a water channel with water substituting for air. Five bridgesection models of different shapes were tested, each of which was driven to move...
Show moreWind loads on a bridge may be classified into two types: the buffeting loads and the selfexcited loads. The research reported in this thesis is concerned with experimental determination of the selfexcited loads in the frequency domain, in particular, their nondimensional coefficients, called flutter derivatives. The experiments were conducted in a water channel with water substituting for air. Five bridgesection models of different shapes were tested, each of which was driven to move harmonically by linkages, and the forces on the linkages were measured to determine the fluid loads. A thinplate model, simulating an airfoil, was also tested and the results were compared with those obtained from the thin airfoil theory. The setup of the experiments and data acquisition, processing and analysis are presented herein.
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Date Issued

1993

PURL

http://purl.flvc.org/fcla/dt/14959

Subject Headings

Bridges, Longspan, Windpressure, BridgesVibration, Structural dynamics

Format

Document (PDF)


Title

Vibration tailoring of inhomogeneous beams and circular plates.

Creator

Pentaras, Demetris., Florida Atlantic University, Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

The vibrational behavior of inhomogeneous beams and circular plates is studied, utilizing the semiinverse method developed by I. Elishakoff and extensively discussed in his recent monograph (2005). The main thread of his methodology is that the knowledge of the mode shape is postulated. The candidate mode shapes can be adopted from relevant static, dynamic or buckling problems. In this study, the exact mode shapes are sought as polynomial functions, in the context of vibration tailoring, i.e...
Show moreThe vibrational behavior of inhomogeneous beams and circular plates is studied, utilizing the semiinverse method developed by I. Elishakoff and extensively discussed in his recent monograph (2005). The main thread of his methodology is that the knowledge of the mode shape is postulated. The candidate mode shapes can be adopted from relevant static, dynamic or buckling problems. In this study, the exact mode shapes are sought as polynomial functions, in the context of vibration tailoring, i.e. designing the structure that possesses the prespecified value. Apparently for the first time in the literature, several closedform solutions for vibration tailoring have been derived for vibrating inhomogeneous beams and circular plates. Twelve new closedform solutions for vibration tailoring have been derived for an inhomogeneous polar orthotropic plate that is either clamped or simply supported around its circumference. Also, the vibration tailoring of a polar orthotropic circular plate with translational spring is analyzed. There is considerable potential of utilizing the developed method for design of functionally graded materials.
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Date Issued

2006

PURL

http://purl.flvc.org/fcla/dt/13344

Subject Headings

Acoustical engineering, Plates (Engineering)VibrationMathematical models, Buckling (Mechanics), Structural analysis

Format

Document (PDF)


Title

Analysis of ship hull and plate vibrations caused by wave forces.

Creator

Lakitosh, Fnu, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

In the present dissertation, the hydrodynamic and hydroelastic characteristics of ship hull and plate vibrations are analyzed using theoretical and numerical methods. The wave forces are determined using a suite of methods which include the FroudeKrylov method for incident wave forces, Wagner's method and ABS rules for the slamming wave force, and numerical methods for nonlinear wave radiation forces. Finite difference methods are developed to determine the wave forced vibrations of ship...
Show moreIn the present dissertation, the hydrodynamic and hydroelastic characteristics of ship hull and plate vibrations are analyzed using theoretical and numerical methods. The wave forces are determined using a suite of methods which include the FroudeKrylov method for incident wave forces, Wagner's method and ABS rules for the slamming wave force, and numerical methods for nonlinear wave radiation forces. Finite difference methods are developed to determine the wave forced vibrations of ship hull plates which are modeled using a range of plate theories including nonlinear plate theory with and without material damping and orthotropic plate theory for stiffened hull plates. For small amplitude deformation of thin plates, a semitheoretical superposition method is used to determine the free and forced vibrations. The transient ship hull vibration due to whipping is also analyzed using the finite difference method. Results, in the form of deformations and stress distributions, are obtained for a range of scantling and wave parameters to identify key parameters to consider in ship structural design.
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Date Issued

2012

PURL

http://purl.flvc.org/FAU/3342196

Subject Headings

Vibration (Marine engineering), Hulls (Naval architecture), Ships, Hydraulic impact, Ocean waves, Mathematical models, Fluid dynamics, Mathematical models

Format

Document (PDF)


Title

Science fiction girlfriends transgender politics and US science fiction television, 1990–present.

Creator

Cava, Peter, Scodari, Christine, Florida Atlantic University, Dorothy F. Schmidt College of Arts and Letters, School of Communication and Multimedia Studies

Abstract/Description

The 1990s ushered in what historian Susan Stryker describes as “a tremendous burst of new transgender activism” in the United States. Concomitantly, the success of Star Trek: The Next Generation led to a renaissance of US science fiction television. This dissertation asks, what is the relation between transgender (trans) politics and US science fiction (sf) television from 1990 to the present? The theoretical framework is Trans/Elemental feminism, a new paradigm developed in the dissertation....
Show moreThe 1990s ushered in what historian Susan Stryker describes as “a tremendous burst of new transgender activism” in the United States. Concomitantly, the success of Star Trek: The Next Generation led to a renaissance of US science fiction television. This dissertation asks, what is the relation between transgender (trans) politics and US science fiction (sf) television from 1990 to the present? The theoretical framework is Trans/Elemental feminism, a new paradigm developed in the dissertation. The method is multiperspectival cultural studies, which considers how the production, content, and reception of media texts and their metatexts collectively determine the texts’ meaning. The data include trade articles about the television industry; published interviews with producers; 3,175 hours of televisual content; commercial advertisements for television programs; films, novels, and webisodes (Web episodes) in selected media franchises; professional reviews; online discussion boards; fan fiction; and fan videos.
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Date Issued

2015

PURL

http://purl.flvc.org/fau/fd/FA00004435, http://purl.flvc.org/fau/fd/FA00004435

Subject Headings

Computer science., Computers., Artificial intelligence., Applied mathematics., Engineering mathematics., Statistical physics., Dynamical systems., Vibration., Dynamics., Computer Science.

Format

Document (PDF)


Title

Noise radiation from an open grid bridge.

Creator

Tournour, Michel Andre., Florida Atlantic University, Cuschieri, Joseph M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering

Abstract/Description

When a vehicle crosses the grid section of an open grid or bascule bridge, a tonal noise is generated. The tonal character of the noise is a consequence of the periodic excitation of both the tire and the grid, that comes from the interaction between the vehicle tire and the periodic grid members. In this thesis, the parameters that control the level and frequency of the generated noise are investigated, with emphasis on understanding the contribution to the overall noise level from the...
Show moreWhen a vehicle crosses the grid section of an open grid or bascule bridge, a tonal noise is generated. The tonal character of the noise is a consequence of the periodic excitation of both the tire and the grid, that comes from the interaction between the vehicle tire and the periodic grid members. In this thesis, the parameters that control the level and frequency of the generated noise are investigated, with emphasis on understanding the contribution to the overall noise level from the vibrations of the grid. Field and laboratory measurements have been performed, together with analytical analysis, on sample grid designs. By determining the acoustic radiation efficiency of the grid, the noise contribution from the grid vibrations is estimated by combing the radiation efficiency with the field measured vibration levels. The results of this study show that the contribution from the grid is small compared to that which may be coming from the vibration of the tire. Without first reducing tire noise, structural modifications to the grid in the form of damping or acoustic baffles will not produce any significant noise reduction.
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Date Issued

1994

PURL

http://purl.flvc.org/fcla/dt/15046

Subject Headings

BridgesDesign and construction, Bridges, Steel plate deck, BridgesNoise, Noise control, BridgesVibration

Format

Document (PDF)
Pages