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Title: Power flow analysis of simple structures.
Creator: Rassineux, Jean-Louis Maurice., Florida Atlantic University, Cuschieri, Joseph M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A Power Flow approach, where the vibrational Power Flow is expressed in terms of mobility functions is analytically investigated for simple connected structures. Using a Power Flow approach the global structure is divided into a series of substructures and the vibrational Power Flow between the substructures expressed in terms of input and transfer mobilities. Depending on the type and shape of the junction, line or point mobilities may be used. While in the case of point joints, the mobility...
Show moreA Power Flow approach, where the vibrational Power Flow is expressed in terms of mobility functions is analytically investigated for simple connected structures. Using a Power Flow approach the global structure is divided into a series of substructures and the vibrational Power Flow between the substructures expressed in terms of input and transfer mobilities. Depending on the type and shape of the junction, line or point mobilities may be used. While in the case of point joints, the mobility functions are only functions of frequency, for line joints the mobility functions are variables of not just the frequency but also of space. In this thesis the application of the Power Flow method is first demonstrated for an L-shaped beam and the method is then extended to the application of a line junction between two plates forming an L-shaped plate. The results obtained in the two cases are compared to results obtained using Finite Element Analysis or Statistical Energy Analysis.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14439
Subject Headings: Structural dynamics
Format: Document (PDF)

Title: In-plane and out-of-plane components of structural intensity in thick structures.
Creator: Grandclement, Cyrille Nicolas., Florida Atlantic University, Cuschieri, Joseph M.
Abstract/Description: In thick structures, vibrational power can propagate by both in-plane and out-of-plane waves. In performing measurements of power flow or structural intensity, it would be required that the components associated with the in-plane or out-of-plane waves be identified. Using a frequency wavenumber approach, the measured structural intensity can be decomposed into its different wave components. In this thesis, simulated structural intensity measurements are presented to demonstrate the use of...
Show moreIn thick structures, vibrational power can propagate by both in-plane and out-of-plane waves. In performing measurements of power flow or structural intensity, it would be required that the components associated with the in-plane or out-of-plane waves be identified. Using a frequency wavenumber approach, the measured structural intensity can be decomposed into its different wave components. In this thesis, simulated structural intensity measurements are presented to demonstrate the use of this frequency wavenumber technique. The results obtained show the distribution of the structural intensity into the wave components. The implementation of this technique using a laser based instrument is discussed. The required characteristics of the instrument, the number of channels, the spacing between the channels, and the phase accuracy, are described. Also, a table to perform the scanning for the frequency wavenumber analysis is presented.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14707
Subject Headings: Structural dynamics, Structural analysis (Engineering)
Format: Document (PDF)

Title: Structural intensity measurements in thick structures.
Creator: Vallory, Joelle., Florida Atlantic University, Cuschieri, Joseph M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Structural intensity is propagated through a thick structure by both in-plane and out-of-plane (transverse) waves. These waves propagate at different phase speeds and therefore it is important to distinguish the components of the structural intensity associated with each wave type. To show the presence of these different wave components, experimental results are performed on a thick beam. Using a frequency-wavenumber analysis, the different waves and contributions to the structural intensity...
Show moreStructural intensity is propagated through a thick structure by both in-plane and out-of-plane (transverse) waves. These waves propagate at different phase speeds and therefore it is important to distinguish the components of the structural intensity associated with each wave type. To show the presence of these different wave components, experimental results are performed on a thick beam. Using a frequency-wavenumber analysis, the different waves and contributions to the structural intensity are identified. The significance of the contributions to the structural intensity are a function of both frequency and thickness of the structure. Using simulated measurements on a thick L-shaped plate, the relative importance between the in-plane and out-of-plane contributions to structural intensity as a function of frequency and thickness is demonstrated. It is shown that in-plane wave contributions increase in importance as frequency or thickness increases.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14697
Subject Headings: Structural dynamics, Noise, Vibration
Format: Document (PDF)

Title: Dynamic stability of fluid-conveying pipes on uniform or non-uniform elastic foundations.
Creator: Vittori, Pablo J., Florida Atlantic University, Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The dynamic behavior of straight cantilever pipes conveying fluid is studied, establishing the conditions of stability for systems, which are only limited to move in a 2D-plane. Internal friction of pipe and the effect of the surrounding fluid are neglected. A universal stability curve showing boundary between the stable and unstable behaviors is constructed by finding solution to equation of motion by exact and high-dimensional approximate methods. Based on the Boobnov-Galerkin method, the...
Show moreThe dynamic behavior of straight cantilever pipes conveying fluid is studied, establishing the conditions of stability for systems, which are only limited to move in a 2D-plane. Internal friction of pipe and the effect of the surrounding fluid are neglected. A universal stability curve showing boundary between the stable and unstable behaviors is constructed by finding solution to equation of motion by exact and high-dimensional approximate methods. Based on the Boobnov-Galerkin method, the critical velocities for the fluid are obtained by using both the eigenfunctions of a cantilever beam (beam functions), as well as the utilization of Duncan's functions. Stability of cantilever pipes with uniform and non-uniform elastic foundations of two types are considered and discussed. Special emphasis is placed on the investigation of the paradoxical behavior previously reported in the literature.
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Date Issued: 2004
PURL: http://purl.flvc.org/fcla/dt/13167
Subject Headings: Strains and stresses, Structural dynamics, Structural stability, Fluid dynamics, Vibration
Format: Document (PDF)

Title: Data gateway for prognostic health monitoring of ocean-based power generation.
Creator: Gundel, Joseph., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: On August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development. Their focus is the research and development of open-ocean current systems and associated infrastructure needed to development and testing prototypes. The generation of power is achieved by using a specialized electric generator with a rotor called a turbine. As with all machines,...
Show moreOn August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development. Their focus is the research and development of open-ocean current systems and associated infrastructure needed to development and testing prototypes. The generation of power is achieved by using a specialized electric generator with a rotor called a turbine. As with all machines, the turbines will need maintenance and replacement as they near the end of their lifecycle. This prognostic health monitoring (PHM) requires data to be collected, stored, and analyzed in order to maximize the lifespan, reduce downtime and predict when failure is eminent. This thesis explores the use of a data gateway which will separate high level software with low level hardware including sensors and actuators. The gateway will v standardize and store the data collected from various sensors with different speeds, formats, and interfaces allowing an easy and uniform transition to a database system for analysis.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3342111
Subject Headings: Machinery, Monitoring, Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics
Format: Document (PDF)

Title: Wavelet de-noising applied to vibrational envelope analysis methods.
Creator: Bertot, Edward Max, Khoshgoftaar, Taghi M., Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: In the field of machine prognostics, vibration analysis is a proven method for detecting and diagnosing bearing faults in rotating machines. One popular method for interpreting vibration signals is envelope demodulation, which allows a technician to clearly identify an impulsive fault source and its severity. However incipient faults -faults in early stages - are masked by in-band noise, which can make the associated impulses difficult to detect and interpret. In this thesis, Wavelet De...
Show moreIn the field of machine prognostics, vibration analysis is a proven method for detecting and diagnosing bearing faults in rotating machines. One popular method for interpreting vibration signals is envelope demodulation, which allows a technician to clearly identify an impulsive fault source and its severity. However incipient faults -faults in early stages - are masked by in-band noise, which can make the associated impulses difficult to detect and interpret. In this thesis, Wavelet De-Noising (WDN) is implemented after envelope-demodulation to improve accuracy of bearing fault diagnostics. This contrasts the typical approach of de-noising as a preprocessing step. When manually measuring time-domain impulse amplitudes, the algorithm shows varying improvements in Signal-to-Noise Ratio (SNR) relative to background vibrational noise. A frequency-domain measure of SNR agrees with this result.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004080, http://purl.flvc.org/fau/fd/FA00004080
Subject Headings: Fluid dynamics, Signal processing, Structural dynamics, Wavelet (Mathematics)
Format: Document (PDF)

Title: Software framework for prognostic health monitoring of ocean-based power generation.
Creator: Bowren, Mark., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: On August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development of prototypes for open-ocean power generation. Maintenance on ocean-based machinery can be very costly. To avoid unnecessary maintenance it is necessary to monitor the condition of each machine in order to predict problems. This kind of prognostic health monitoring (PHM) requires a...
Show moreOn August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development of prototypes for open-ocean power generation. Maintenance on ocean-based machinery can be very costly. To avoid unnecessary maintenance it is necessary to monitor the condition of each machine in order to predict problems. This kind of prognostic health monitoring (PHM) requires a condition-based maintenance (CBM) system that supports diagnostic and prognostic analysis of large amounts of data. Research in this field led to the creation of ISO13374 and the development of a standard open-architecture for machine condition monitoring. This thesis explores an implementation of such a system for ocean-based machinery using this framework and current open-standard technologies.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3342035
Subject Headings: Machinery, Monitoring, Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics
Format: Document (PDF)

Title: Power flow analysis of a structure subjected to distributed excitation.
Creator: Cimerman, Benjamin Pierre., Florida Atlantic University, Cuschieri, Joseph M.
Abstract/Description: An analytical investigation based on the Power Flow Method is presented for the prediction of vibrational Power Flow in simple connected structures subjected to various forms of distributed excitations. The principle of the power flow method consists of dividing the global structure into a series of substructures which can be analyzed independently and then coupled through the boundary conditions. Power flow expressions are derived for an L-shaped plate structure, subjected to any form of...
Show moreAn analytical investigation based on the Power Flow Method is presented for the prediction of vibrational Power Flow in simple connected structures subjected to various forms of distributed excitations. The principle of the power flow method consists of dividing the global structure into a series of substructures which can be analyzed independently and then coupled through the boundary conditions. Power flow expressions are derived for an L-shaped plate structure, subjected to any form of distributed mechanical excitation or excited by an acoustic plane wave. In the latter case air loading is considered to have a significant effect on the power input to the structure. Fluid-structure interaction considerations lead to the derivation of a corrected mode shape for the normal velocity, and the determination of the scattered pressure components in the expressions for the Power Flow.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/14578
Subject Headings: Structural dynamics, Plates (Engineering)--Vibration
Format: Document (PDF)

Title: Blast/explosion resistant analysis of composite steel girder bridge system.
Creator: Zhou, Fang., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: The design of bridge structures to resist explosive loads has become more of a concern to the engineering community. This thesis proposes a method to evaluate the effects of conventional blast loads on a two span continuous composite steel girder bridge system. The bridge design is based on AASHTO LRFD method. Resistance capacities of bridge deck and composite steel girder are calculated according to AASHTO specifications. Equivalent blast pressures on the bridge components are obtained....
Show moreThe design of bridge structures to resist explosive loads has become more of a concern to the engineering community. This thesis proposes a method to evaluate the effects of conventional blast loads on a two span continuous composite steel girder bridge system. The bridge design is based on AASHTO LRFD method. Resistance capacities of bridge deck and composite steel girder are calculated according to AASHTO specifications. Equivalent blast pressures on the bridge components are obtained. Response and performance of concrete deck, steel girders, and supporting piers are evaluated under typical blast loads. The blast induced force in the bridge components are computed in the static analyses for varying amounts of TNT. The blast effects in the supporting pier are determined using both static and dynamic analyses. Further research needs to be done in the dynamic analysis of the bridge system subjected to blast loads.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/227976
Subject Headings: Steel, Structural, Testing, Bridges, Design and construction, Structural dynamics
Format: Document (PDF)

Title: Response analysis of structures including effects of soil-structure interaction.
Creator: Yu, Jun., Florida Atlantic University, Yong, Yan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The objective of the study is to determine the structural response to external force and earthquake excitations with consideration of soil-structure interaction. The physical model concerned herein is an N-story building on a rigid or flexible foundation embedded in a layered soil medium. In this substructure approach, the soil medium and the structure are treated as one-dimensional waveguides and their motions are characterized as wave scattering. To include effects of soil-structure...
Show moreThe objective of the study is to determine the structural response to external force and earthquake excitations with consideration of soil-structure interaction. The physical model concerned herein is an N-story building on a rigid or flexible foundation embedded in a layered soil medium. In this substructure approach, the soil medium and the structure are treated as one-dimensional waveguides and their motions are characterized as wave scattering. To include effects of soil-structure interaction, the foundation response is expressed as a summation of influence functions, which are defined as the response to a simple stress distribution over the contact surface between the soil and foundation. The analysis, therefore, is carried out without solving integral equations. The coupling effect is recovered by using equilibrium, compatibility and reciprocal conditions. As a result, the structural response solution is expressed in terms of parameters of a seismic source and external excitations, and can be used in a statistical analysis if uncertainties of these parameters are taken into account.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/12425
Subject Headings: Soil-structure interaction, Earthquake engineering, Structural dynamics, Foundations
Format: Document (PDF)

Title: Design and analysis of an ocean current turbine performance assessment system.
Creator: Young, Matthew T., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis proposes a sensor approach for quantifying the hydrodynamic performance of Ocean Current Turbines (OCT), and investigates the influence of sensor-specific noise and sampling rates on calculated turbine performance. Numerical models of the selected sensors are developed, and then utilized to add stochastic measurement error to numerically-generated, non-stochastic OCT data. Numerically-generated current velocity and turbine performance measurements are used to quantify the relative...
Show moreThis thesis proposes a sensor approach for quantifying the hydrodynamic performance of Ocean Current Turbines (OCT), and investigates the influence of sensor-specific noise and sampling rates on calculated turbine performance. Numerical models of the selected sensors are developed, and then utilized to add stochastic measurement error to numerically-generated, non-stochastic OCT data. Numerically-generated current velocity and turbine performance measurements are used to quantify the relative influence of sensor-specific error and sampling limitations on sensor measurements and calculated OCT performance results. The study shows that the addition of sensor error alters the variance and mean of OCT performance metric data by roughly 7.1% and 0.24%, respectively, for four evaluated operating conditions. It is shown that sensor error results in a mean, maximum and minimum performance metric to Signal to Noise Ration (SNR) of 48.6% and 6.2%, respectively.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3359164
Subject Headings: Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Stochastic processes, Rotors, Design and construction, Testing
Format: Document (PDF)

Title: Development of an integrated computational tool for design and analysis of composite turbine blades under ocean current loading.
Creator: Zhou, Fang., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A computational tool has been developed by integrating National Renewable Energy Laboratory (NREL) codes, Sandia National Laboratories' NuMAD, and ANSYS to investigate a horizontal axis composite ocean current turbine. The study focused on the design, analysis, and life prediction of composite blade considering random ocean current, cyclic rotation, and hurricane-driven ocean current. A structural model for a horizontal axis FAU research OCT blade was developed. Following NREL codes were used...
Show moreA computational tool has been developed by integrating National Renewable Energy Laboratory (NREL) codes, Sandia National Laboratories' NuMAD, and ANSYS to investigate a horizontal axis composite ocean current turbine. The study focused on the design, analysis, and life prediction of composite blade considering random ocean current, cyclic rotation, and hurricane-driven ocean current. A structural model for a horizontal axis FAU research OCT blade was developed. Following NREL codes were used: PreCom, BModes, ModeShape, AeroDyn and FAST. PreComp was used to compute section properties of the OCT blade. BModes and ModeShape calculated the mode shapes of the blade. Hydrodynamic loading on the OCT blade was calculated by modifying the inputs to AeroDyn and FAST. These codes were then used to obtain the dynamic response of the blade, including blade tip displacement, normal force (FN) and tangential force (FT), flap and edge bending moment distribution with respect to blade rotation.
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Date Issued: 2013
PURL: http://purl.flvc.org/fcla/dt/3362582
Subject Headings: Structural dynamics, Fluid dynamics, Marine turbines, Mathematical models, Turbines, Blades, Design and construction
Format: Document (PDF)

Title: Design and finite element analysis of an ocean current turbine blade.
Creator: Asseff, Nicholas S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A composite 3 meter ocean current turbine blade has been designed and analyzed using Blade Element Theory (BET) and commercial Finite Element Modeling (FEM) code, ANSYS. It has been observed that using the numerical BET tool created, power production up to 141 kW is possible from a 3 bladed rotor in an ocean current of 2.5 m/s with the proposed blade design. The blade is of sandwich construction with carbon fiber skin and high density foam core. It also contains two webs made of S2-glass for...
Show moreA composite 3 meter ocean current turbine blade has been designed and analyzed using Blade Element Theory (BET) and commercial Finite Element Modeling (FEM) code, ANSYS. It has been observed that using the numerical BET tool created, power production up to 141 kW is possible from a 3 bladed rotor in an ocean current of 2.5 m/s with the proposed blade design. The blade is of sandwich construction with carbon fiber skin and high density foam core. It also contains two webs made of S2-glass for added shear rigidity. Four design cases were analyzed, involving differences in hydrodynamic shape, material properties, and internal structure. Results from the linear static structural analysis revealed that the best design provides adequate stiffness and strength to produce the proposed power without any structural failure. An Eigenvalue Buckling analysis confirmed that the blade would not fail from buckling prior to overstressed laminate failure if the loading was to exceed the Safety Factor.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/221944
Subject Headings: Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Composite materials, Mathematical models
Format: Document (PDF)

Title: Numerical performance prediction for FAU's first generation ocean current turbine.
Creator: Vanrietvelde, Nicolas., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis presents the analytically predicted position, motion, attitude, power output and forces on Florida Atlantic University's (FAU) first generation ocean current turbine for a wide range of operating conditions. These values are calculated using a 7- DOF dynamics simulation of the turbine and the cable that attaches it to the mooring system. The numerical simulation modifications and upgrades completed in this work include developing a wave model including the effects of waves into...
Show moreThis thesis presents the analytically predicted position, motion, attitude, power output and forces on Florida Atlantic University's (FAU) first generation ocean current turbine for a wide range of operating conditions. These values are calculated using a 7- DOF dynamics simulation of the turbine and the cable that attaches it to the mooring system. The numerical simulation modifications and upgrades completed in this work include developing a wave model including the effects of waves into the simulation, upgrading the rotor model to specify the number of blades and upgrading the cable model to specify the number of cable elements. This enhanced simulation is used to quantify the turbine's performance in a wide range of currents, wave fields and when stopping and starting the rotor. For a uniform steady current this simulation predicts that when the rotor is fixed in 1.5 m/s current the drag on the turbine is 3.0 kN, the torque on the rotor is 384 N-m, the turbine roll and pitch are 2.4º and -1.2º . When the rotor is allowed to spin up to the rotational velocity where the turbine produces maximum power, the turbine drag increases to 7.3 kN, the torque increases to 1482 N-m, the shaft power is 5.8 kW, the turbine roll increases to 9º and the turbine pitch stays constant. Subsequently, a sensitivity analysis is done to evaluate changes in turbine performance caused by changes in turbine design and operation. This analysis show, among other things, that a non-axial flow on the turbine of up to 10º has a minimal effect on net power output and that the vertical stable position of the turbine varies linearly with the weight/buoyancy of the turbine with a maximum variation of 1.77 m for each increase or decrease of 1 kg at a current speed of 0.5 m/s.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/2182033
Subject Headings: Marine turbines, Mathematical models, Structural dynamics, Rotors, Design and construction, Testing, Fluid dynamics
Format: Document (PDF)

Title: Numerical simulation tool for moored marine hydrokinetic turbines.
Creator: Hacker, Basil L., Ananthakrishnan, Palaniswamy, VanZwieten, James H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The research presented in this thesis utilizes Blade Element Momentum (BEM) theory with a dynamic wake model to customize the OrcaFlex numeric simulation platform in order to allow modeling of moored Ocean Current Turbines (OCTs). This work merges the advanced cable modeling tools available within OrcaFlex with well documented BEM rotor modeling approach creating a combined tool that was not previously available for predicting the performance of moored ocean current turbines. This tool allows...
Show moreThe research presented in this thesis utilizes Blade Element Momentum (BEM) theory with a dynamic wake model to customize the OrcaFlex numeric simulation platform in order to allow modeling of moored Ocean Current Turbines (OCTs). This work merges the advanced cable modeling tools available within OrcaFlex with well documented BEM rotor modeling approach creating a combined tool that was not previously available for predicting the performance of moored ocean current turbines. This tool allows ocean current turbine developers to predict and optimize the performance of their devices and mooring systems before deploying these systems at sea. The BEM rotor model was written in C++ to create a back-end tool that is fed continuously updated data on the OCT’s orientation and velocities as the simulation is running. The custom designed code was written specifically so that it could operate within the OrcaFlex environment. An approach for numerically modeling the entire OCT system is presented, which accounts for the additional degree of freedom (rotor rotational velocity) that is not accounted for in the OrcaFlex equations of motion. The properties of the numerically modeled OCT were then set to match those of a previously numerically modeled Southeast National Marine Renewable Energy Center (SNMREC) OCT system and comparisons were made. Evaluated conditions include: uniform axial and off axis currents, as well as axial and off axis wave fields. For comparison purposes these conditions were applied to a geodetically fixed rotor, showing nearly identical results for the steady conditions but varied, in most cases still acceptable accuracy, for the wave environment. Finally, this entire moored OCT system was evaluated in a dynamic environment to help quantify the expected behavioral response of SNMREC’s turbine under uniform current.
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Date Issued: 2013
PURL: http://purl.flvc.org/fau/fd/FA0004024
Subject Headings: Fluid dynamics, Hydrodynamics -- Research, Marine turbines -- Mathematical models, Ocean wave power, Structural dynamics
Format: Document (PDF)

Title: Numerical simulation and prediction of loads in marine current turbine full-scale rotor blades.
Creator: Senat, Junior., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Marine current turbines are submerged structures and subjected to loading conditions from both the currents and wave effects. The associated phenomena posed significant challenge to the analyses of the loading response of the rotor blades and practical limitations in terms of device location and operational envelopes. The effect of waves on marine current turbines can contribute to the change of flow field and pressure field around the rotor and hence changes the fluid forces on the rotor....
Show moreMarine current turbines are submerged structures and subjected to loading conditions from both the currents and wave effects. The associated phenomena posed significant challenge to the analyses of the loading response of the rotor blades and practical limitations in terms of device location and operational envelopes. The effect of waves on marine current turbines can contribute to the change of flow field and pressure field around the rotor and hence changes the fluid forces on the rotor. However, the effect of the waves on the rotor depends on the magnitude and direction of flow velocity that is induced by the waves. An analysis is presented for predicting the torque, thrust, and bending moments resulting from the wave-current interactions at the root of rotor blades in a horizontal axis marine current turbine using the blade element-momentum (BEM) theory combined with linear wave theory. Parametric studies are carried out to better understand the influence of important parameters , which include wave height, wave frequency, and tip-speed ratio on the performance of the rotor. The periodic loading on the blade due to the steady spatial variation of current speeds over the rotor swept area is determined by a limited number of parameters, including Reynolds number, lift and drag coefficients, thrust and torque coefficients, and power coefficient. The results established that the BEM theory combined with linear wave theory can be used to analyze the wavecurrent interactions in full-scale marine current turbine. The power and thrust coefficients can be analyzed effectively using the numerical BEM theory in conjunction with corrections to the tip loss coefficient and 3D effects., It has been found both thrust and torque increase as the current speed increases, and in longer waves the torque is relatively sensitive to the variation of wave height. Both in-plane and out-of-plane bending moments fluctuate significantly and can be predicted by linear wave theory with blade element-momentum theory.
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Date Issued: 2011
PURL: http://purl.flvc.org/FAU/3172695
Subject Headings: Marine turbines, Mathematical models, Structural dynamics, Fluid dynamics, Rotors, Design and construction
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 wavelet-based transforms (the Streaming Wavelet Transform, Short-Time Wavelet Packet Decomposition, and Streaming Wavelet Packet Decomposition) and propose modifications to the existing Short-TIme Wavelet Transform. ... The proposed algorithms also create and select frequency-band 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: Wind effect on super-tall buildings using computational fluid dynamics and structural dynamics.
Creator: Assaad, Bilal, Arockiasamy, Madasamy, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Super-tall buildings located in high velocity wind regions are highly vulnerable to large lateral loads. Designing for these structures must be done with great engineering judgment by structural professionals. Present methods of evaluating these loads are typically by the use of American Society of Civil Engineers 7-10 standard, field measurements or scaled wind tunnel models. With the rise of high performance computing nodes, an emerging method based on the numerical approach of...
Show moreSuper-tall buildings located in high velocity wind regions are highly vulnerable to large lateral loads. Designing for these structures must be done with great engineering judgment by structural professionals. Present methods of evaluating these loads are typically by the use of American Society of Civil Engineers 7-10 standard, field measurements or scaled wind tunnel models. With the rise of high performance computing nodes, an emerging method based on the numerical approach of Computational Fluid Dynamics has created an additional layer of analysis and loading prediction alternative to conventional methods. The present document uses turbulence modeling and numerical algorithms by means of Reynolds-averaged Navier-Stokes and Large Eddy Simulation equations applied to a square prismatic prototype structure in which its dynamic properties have also been investigated. With proper modeling of the atmospheric boundary layer flow, these numerical techniques reveal important aerodynamic properties and enhance flow visualization to structural engineers in a virtual environment.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004343, http://purl.flvc.org/fau/fd/FA00004343
Subject Headings: Boundary layer control, Buildings -- Aerodynamics, Computational fluid dynamics, Structural dynamics -- Data processing, Vortex motion
Format: Document (PDF)

Title: Methodology for fault detection and diagnostics in an ocean turbine using vibration analysis and modeling.
Creator: Mjit, Mustapha., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis describes a methodology for mechanical fault detection and diagnostics in an ocean turbine using vibration analysis and modeling. This methodology relies on the use of advanced methods for machine vibration analysis and health monitoring. Because of some issues encountered with traditional methods such as Fourier analysis for non stationary rotating machines, the use of more advanced methods such as Time-Frequency Analysis is required. The thesis also includes the development of...
Show moreThis thesis describes a methodology for mechanical fault detection and diagnostics in an ocean turbine using vibration analysis and modeling. This methodology relies on the use of advanced methods for machine vibration analysis and health monitoring. Because of some issues encountered with traditional methods such as Fourier analysis for non stationary rotating machines, the use of more advanced methods such as Time-Frequency Analysis is required. The thesis also includes the development of two LabVIEW models. The first model combines the advanced methods for on-line condition monitoring. The second model performs the modal analysis to find the resonance frequencies of the subsystems of the turbine. The dynamic modeling of the turbine using Finite Element Analysis is used to estimate the baseline of vibration signals in sensors locations under normal operating conditions of the turbine. All this information is necessary to perform the vibration condition monitoring of the turbine.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/369198
Subject Headings: Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Composite materials, Mathematical models, Elastic analysis (Engineering)
Format: Document (PDF)

Title: Buckling of composite cylindrical shells with geometric, thickness and material imperfections.
Creator: Li, Yiwei., Florida Atlantic University, Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This dissertation deals with the determination of buckling loads of composite cylindrical shell structures which involve uncertainty either in geometry, namely thickness variation, or in material properties. Systematic research has been carried out, which evolves from the simple isotropic cases to anisotropic cases. Since the initial geometric imperfection has a dominant role in the reduction of those imperfection-sensitive structures such as cylindrical shells, the combined effect of...
Show moreThis dissertation deals with the determination of buckling loads of composite cylindrical shell structures which involve uncertainty either in geometry, namely thickness variation, or in material properties. Systematic research has been carried out, which evolves from the simple isotropic cases to anisotropic cases. Since the initial geometric imperfection has a dominant role in the reduction of those imperfection-sensitive structures such as cylindrical shells, the combined effect of thickness variation and initial imperfection is also investigated in depth. Both analytic and numerical methods are used to derive the solutions to the problems and asymptotic formulas relating the buckling load to the geometric (thickness variation and/or initial imperfection) parameter are established. It is shown that the axisymmetric thickness variation has the most detrimental effect on the buckling load when the modal number of thickness variation is twice as much as that of the classical buckling mode. For the composite shells with uncertainty in material properties, the convex modelling is employed to evaluate the variability of buckling load. Based on the experimental data for the elastic moduli of the composite laminates, the upper and lower bounds of the buckling load are derived, which are numerically substantiated by the results from nonlinear programming. These bounds will be useful in practice and can provide engineers with a better view of the real load-carrying capacity of the composite structure. Finally, the elastic modulus is modeled as a function of coordinates to complete the study on variability of material property so that the result can be obtained to account for the situation where the elastic modulus is different from one place to another in the structure.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/12444
Subject Headings: Composite materials, Buckling (Mechanics), Shells (Engineering), Structural dynamics
Format: Document (PDF)

Structural dynamics (29)	+ -
Fluid dynamics (13)	+ -
Mathematical models (13)	+ -
Marine turbines (12)	+ -
Design and construction (7)	+ -

Composite materials (5)	+ -
Rotors (4)	+ -
Testing (4)	+ -
Vibration (4)	+ -
Aerodynamic noise (3)	+ -
Blades (3)	+ -
Computational fluid dynamics (3)	+ -
Soil-structure interaction (3)	+ -
Structural analysis (Engineering) (3)	+ -
Structural dynamics. (3)	+ -
Turbines (3)	+ -
Acoustic models (2)	+ -
Computational fluid dynamcs (2)	+ -
Fatigue (2)	+ -
Feedback control systems (2)	+ -
Machinery (2)	+ -
Marine turbines -- Mathematical models (2)	+ -
Materials (2)	+ -
Monitoring (2)	+ -
Ocean wave power (2)	+ -
Offshore structures (2)	+ -
Offshore structures--Dynamics (2)	+ -
Plates (Engineering)--Vibration (2)	+ -
Stochastic processes (2)	+ -
Turbulence -- Mathematical models (2)	+ -

College of Engineering and Computer Science (36)	+ -
Department of Ocean and Mechanical Engineering (26)	+ -
Florida Atlantic University (23)	+ -
Department of Civil, Environmental and Geomatics Engineering (6)	+ -
Cuschieri, Joseph M. (5)	+ -

Department of Computer and Electrical Engineering and Computer Science (4)	+ -
Elishakoff, Isaac (3)	+ -
Bryan, Benjamin Skyler (2)	+ -
Glegg, Stewart A. L. (2)	+ -
Mahfuz, Hassan (2)	+ -
Reddy, Dronnadula V. (2)	+ -
Su, Tsung-Chow (2)	+ -
VanZwieten, James H. (2)	+ -
Zhou, Fang. (2)	+ -
Akram, Mohammad Wasim (1)	+ -
Ananthakrishnan, Palaniswamy (1)	+ -
Arockiasamy, Madasamy (1)	+ -
Assaad, Bilal (1)	+ -
Asseff, Nicholas S. (1)	+ -
Beaujean, Pierre-Philippe (1)	+ -
Bertot, Edward Max (1)	+ -
Bowren, Mark. (1)	+ -
Buchmann, Patrick Pierre. (1)	+ -
Calle, Oscar F. (1)	+ -
Canino, Marco M. (1)	+ -
Carlsson, Leif A. (1)	+ -
Cimerman, Benjamin Pierre. (1)	+ -
Cribbs, Allison Rose. (1)	+ -
Dhanak, Manhar R. (1)	+ -
Driscoll, Frederick R. (1)	+ -

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