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Title: Far-Field Noise From a Rotor in a Wind Tunnel.
Creator: Grant, Justin Alexander, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an...
Show moreThis project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an inhomogeneous flow, and compares them to measured noise radiated from the rotor at prescribed observer locations. Discrepancies between the measurements and predictions led to comprehensive study of the flow in the wind tunnel and the discovery of a vortex upstream of the rotor at low advance ratios. The study presents results of RANS simulations. The static pressure and velocity profile in the domain near the rotor's tip gap region were compared to measurements obtained from a pressure port array and a PIV visualization of the rotor in the wind tunnel.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004501, http://purl.flvc.org/fau/fd/FA00004501
Subject Headings: Aerodynamic noise, Computational fluid dynamics, Fluid dynamic measurement, Fluid mechanics -- Mathematical models, Fluid structure interactioin, Turbomachines -- Fluid dynamics, Turbulence -- Mathematical models, Unsteady flow (Fluid dynamics)
Format: Document (PDF)

Title: Noise Radiation From A Cylindrical Embossment Immersed In Turbulent Boundary Layer Flow.
Creator: Bryan, Benjamin Skyler, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This dissertation will consider the sound radiation from forward-facing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forward-facing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the...
Show moreThis dissertation will consider the sound radiation from forward-facing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forward-facing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the original theory could be adjusted to include a mixed scaling which gives a better prediction. RANS simulations have been performed and used to support the similarities between the forward-facing step and the cylindrical embossment. The simulations revealed that the cylindrical embossment exhibits a separation zone similar to that of the forward-facing step. This separation zone has been shown to be the dominant source of noise on the forward-facing step in previous works and therefore was expected to be the major source of sound from the cylindrical embossment. The sensitivity of this separation zone to the different parameters of the flow has been investigated by performing several simulations with different conditions and geometries. The separation zone was seen to be independent of Reynolds number based on boundary layer thickness but was directly dependent on the height of the cylinder. The theory outlined in Glegg et al (2014) was then reformulated for use with a cylindrical embossment and the predictions have been compared with wind tunnel measurements. The final predictions show good agreement with the wind tunnel measurements and the far-field sound shows a clearly defined directionality that is similar to an axial dipole at low frequencies.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004484, http://purl.flvc.org/fau/fd/FA00004484
Subject Headings: Acoustic models, Aerodynamic noise, Computational fluid dynamcs, Fluid structure interaction, Structural dynamics, Turbulence -- Mathematical models
Format: Document (PDF)

Title: Noise radiation from small steps and cubic roughness elements in turbulent boundary layer flow.
Creator: Bryan, Benjamin Skyler, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Ji and Wang (2010) propose that the dominant source of sound from a forward facing step is the stream wise dipole on the face of the step and that sources acting normal to the flow are negligible. Sound radiation normal to flow of forward facing steps has been measured in wind tunnel experiments previously by Farabee and Casarella (1986, 1991) and Catlett (2010). A method for evaluating sound radiation from surface roughness proposed in Glegg and Devenport (2009) has been adapted and applied...
Show moreJi and Wang (2010) propose that the dominant source of sound from a forward facing step is the stream wise dipole on the face of the step and that sources acting normal to the flow are negligible. Sound radiation normal to flow of forward facing steps has been measured in wind tunnel experiments previously by Farabee and Casarella (1986, 1991) and Catlett (2010). A method for evaluating sound radiation from surface roughness proposed in Glegg and Devenport (2009) has been adapted and applied to flow over a forward facing step which addresses the sound normal to the flow that was previously unaccounted for. Far-field radiation predictions based on this method have been compared with wind tunnel measurements and show good agreement. A second method which evaluates the forcing from a vortex convected past surface roughness using RANS calculations and potential flow information is also evaluated.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3358330
Subject Headings: Turbulence, Mathematical models, Aerodynamic noise, Fluid-structure interaction, Structural dynamics, Acoustic models, Computational fluid dynamcs
Format: Document (PDF)

Title: Model analysis of a mooring system for an ocean current turbine testing platform.
Creator: Cribbs, Allison Rose., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: In response to Florida's growing energy needs and drive to develop renewable power, Florida Atlantic Universitys Center for Ocean Energy Technology (COET) plans to moor a 20 kW test turbine in the Florida Current. No permanent mooring systems for deepwater hydrokinetic turbines have been constructed and deployed, therefore little if anything is known about the performance of these moorings. To investigate this proposed mooring system, a numeric model is developed and then used to predict the...
Show moreIn response to Florida's growing energy needs and drive to develop renewable power, Florida Atlantic Universitys Center for Ocean Energy Technology (COET) plans to moor a 20 kW test turbine in the Florida Current. No permanent mooring systems for deepwater hydrokinetic turbines have been constructed and deployed, therefore little if anything is known about the performance of these moorings. To investigate this proposed mooring system, a numeric model is developed and then used to predict the static and dynamic behavior of the mooring system and attachments. The model has been created in OrcaFlex and includes two surface buoys and an operating turbine. Anchor chain at the end of the mooring line develops a catenary, providing compliance. Wind, wave, and current models are used to represent the environmental conditions the system is expected to experience and model the dynamic effects on the system. The model is then used to analyze various components of the system. The results identify that a mooring attachment point 1.25 m forward of the center of gravity on the mooring buoy is ideal, and that the OCDP and turbine tether lengths should be no shorter than 25 and 44 m, respectively. Analysis performed for the full system identify that the addition of the floats decreases the tension at the MTB attachment location by 26.5 to 29.5% for minimum current, and 0.10 to 0.31% for maximum current conditions.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2974432
Subject Headings: Marine turbines, Mathematical models, Structural dynamics, Rotors, Design and construction, Offshore structures, Testing
Format: Document (PDF)

Title: Finite Element Modeling and Fatigue Analysis of Composite Turbine Blades under Random Ocean Current and Turbulence.
Creator: Canino, Marco M., Mahfuz, Hassan, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Several modifications have been implemented to numerical simulation codes based on blade element momentum theory (BEMT), for application to the design of ocean current turbine (OCT) blades. The modifications were applied in terms of section modulus and include adjustments due to core inclusion, buoyancy, and added mass. Hydrodynamic loads and mode shapes were calculated using the modified BEMT based analysis tools. A 3D model of the blade was developed using SolidWorks. The model was...
Show moreSeveral modifications have been implemented to numerical simulation codes based on blade element momentum theory (BEMT), for application to the design of ocean current turbine (OCT) blades. The modifications were applied in terms of section modulus and include adjustments due to core inclusion, buoyancy, and added mass. Hydrodynamic loads and mode shapes were calculated using the modified BEMT based analysis tools. A 3D model of the blade was developed using SolidWorks. The model was integrated with ANSYS and several loading scenarios, calculated from the modified simulation tools, were applied. A complete stress and failure analysis was then performed. Additionally, the rainflow counting method was used on ocean current velocity data to determine the loading histogram for fatigue analysis. A constant life diagram and cumulative fatigue damage model were used to predict the OCT blade life. Due to a critical area of fatigue failure being found in the blade adhesive joint, a statistical analysis was performed on experimental adhesive joint data.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004727, http://purl.flvc.org/fau/fd/FA00004727
Subject Headings: Composite materials -- Fatigue, Finite element method, Fluid dynamics, Marine turbines -- Mathematical models, Ocean wave power, Structural dynamics
Format: Document (PDF)

Title: Numerical Assessment of Eddy-Viscosity Turbulence Models of an Axial-Flow Turbine at a Low Reynolds Number.
Creator: Estrada, Nick Dagoberto, Moslemian, Davood, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The flow field behavior of axial flow turbines is of great importance, especially in modern designs that may operate at a low Reynolds number. At these low Reynolds numbers, the efficiency loss is significantly augmented compared to higher Reynolds number flows. A detailed incompressible numerical study of a single stage axial-flow turbine at a low Reynolds number is investigated with the use of multiple eddy-viscosity turbulence models. The study includes epistemic uncertainty quantification...
Show moreThe flow field behavior of axial flow turbines is of great importance, especially in modern designs that may operate at a low Reynolds number. At these low Reynolds numbers, the efficiency loss is significantly augmented compared to higher Reynolds number flows. A detailed incompressible numerical study of a single stage axial-flow turbine at a low Reynolds number is investigated with the use of multiple eddy-viscosity turbulence models. The study includes epistemic uncertainty quantification as a form of numerical error estimation. The numerical results show good qualitative and quantitative agreement with experimental data. It was found that the shear stress transport (SST) k - ω turbulence model with rotation/curvature correction and inclusion of transition modeling is most capable at predicting the mean velocity distribution, which is further enhanced when the URANS formulation is employed. However, all the cases indicate a large variation in the prediction of the root-mean-squared of the turbulent velocity fluctuations.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004587, http://purl.flvc.org/fau/fd/FA00004587
Subject Headings: Turbomachines--Fluid dynamics., Turbulence--Mathematical models., Structural dynamics., Viscous flow--Mathematical models., Reynolds number., Axial flow.
Format: Document (PDF)

Title: Numerical Simulation of an Ocean Current Turbine Operating in a Wake Field.
Creator: Pyakurel, Parakram, VanZwieten, James H., Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: An Ocean Current Turbine (OCT) numerical simulation for creating, testing and tuning flight and power takeoff controllers, as well as for farm layout optimization is presented. This simulation utilizes a novel approach for analytically describing oceanic turbulence. This approach has been integrated into a previously developed turbine simulation that uses unsteady Blade Element Momentum theory. Using this, the dynamical response and power production of a single OCT operating in ambient...
Show moreAn Ocean Current Turbine (OCT) numerical simulation for creating, testing and tuning flight and power takeoff controllers, as well as for farm layout optimization is presented. This simulation utilizes a novel approach for analytically describing oceanic turbulence. This approach has been integrated into a previously developed turbine simulation that uses unsteady Blade Element Momentum theory. Using this, the dynamical response and power production of a single OCT operating in ambient turbulence is quantified. An approach for integrating wake effects into this single device numerical simulation is presented for predicting OCT performance within a farm. To accomplish this, far wake characteristics behind a turbine are numerically described using analytic expressions derived from wind turbine wake models. These expressions are tuned to match OCT wake characteristics calculated from CFD analyses and experimental data. Turbine wake is characterized in terms of increased turbulence intensities and decreased mean wake velocities. These parameters are calculated based on the performance of the upstream OCT and integrated into the environmental models used by downstream OCT. Simulation results are presented that quantify the effects of wakes on downstream turbine performance over a wide range of relative downstream and cross stream locations for both moored and bottom mounted turbine systems. This is done to enable the development and testing of flight and power takeoff controllers designed for maximizing energy production and reduce turbine loadings.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004737, http://purl.flvc.org/fau/fd/FA00004737
Subject Headings: Turbulence--Mathematical models., Marine turbines--Mathematical models., Wind turbines--Aerodynamics--Mathematical models., Structural dynamics., Computational fluid dynamics., Fluid dynamic measurements., Atmospheric circulation.
Format: Document (PDF)

Title: Dynamic positioning and motion mitigation of a scaled sea basing platform.
Creator: Marikle, Sean P., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A 6-Degree Of Freedom (DOF) numeric model and computer simulation along with the 1/10th scale physical model of the Rapidly Deployable Stable Platform (RDSP) are being developed at Florida Atlantic University in response to military needs for ocean platforms with improved sea keeping characteristics. The RDSP is a self deployable spar platform with two distinct modes of operation enabling long distance transit and superior seakeeping. The focus of this research is the development of a Dynamic...
Show moreA 6-Degree Of Freedom (DOF) numeric model and computer simulation along with the 1/10th scale physical model of the Rapidly Deployable Stable Platform (RDSP) are being developed at Florida Atlantic University in response to military needs for ocean platforms with improved sea keeping characteristics. The RDSP is a self deployable spar platform with two distinct modes of operation enabling long distance transit and superior seakeeping. The focus of this research is the development of a Dynamic Position (DP) and motion mitigation system for the RDSP. This will be accomplished though the validation of the mathematical simulation, development of a novel propulsion system, and implementation of a PID controller. The result of this research is an assessment of the response characteristics of the RDSP that quantifies the performance of the propulsion system coupled with active control providing a solid basis for further controller development and operational testing.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/228767
Subject Headings: Inertial navigation systems, Mobile offshore structures, Design and construction, Wave motion, Theory of, Offshore structures, Dynamics, Feedback control systems
Format: Document (PDF)

Title: Modeling of Flexible Pipe for Culvert Application under Shallow Burial Condition.
Creator: Limpeteeprakarn, Terdkiat, Carlsson, Leif A., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Flexible thermoplastic p1pes under field and laboratory loading conditions have been examined in the present study. The flexible pipes were tested under truck loading application with shallow soil cover. The pipe-soil system response includes soil stresses around and above the buried pipes, vertical pipe crown diametral strain, and circumferential pipe wall strains. Modeling the pipe-soil system is made using plane strain and thin ring assumptions. A thin ring model using Castigliano's...
Show moreFlexible thermoplastic p1pes under field and laboratory loading conditions have been examined in the present study. The flexible pipes were tested under truck loading application with shallow soil cover. The pipe-soil system response includes soil stresses around and above the buried pipes, vertical pipe crown diametral strain, and circumferential pipe wall strains. Modeling the pipe-soil system is made using plane strain and thin ring assumptions. A thin ring model using Castigliano's theorem is developed to analyze the behavior and response of a flexible pipe under well defined loading conditions and simulate the behavior of the buried pipe under the live load application. Laboratory work was carried out to study the pipe behavior and response under two-point, three-point, and four-point loading configurations. The thin ring model predictions show good agreement with classical solutions specially valid for two-point and three-point loading configurations. Laboratory results were also in good agreement with the predictions. Laboratory results show that the maximum tensile strain for the four-point loading test occurs at inner pipe crown region. Comprehensive efforts were made to correlate the thin ring model predictions with the field test results; however, it appears that the thin ring model cannot be used to simulate the effect of the live load application. A major source of the differences between the predicted and measured values is attributed to the applied load magnitude. A further investigation was carried out to examine the applicability of the model to study the general pipe behavior. The predicted hoop pipe wall strain profile was found to be similar to that of the reported strain profile by Rogers under overall poor soil support condition. Comparison of soil stress distribution shows that the 2D prediction approach provides nonconservative results while the FE analysis agrees more favorably with the measured pressure data. Overall, FE analysis shows that a linearly elastic isotropic model for the surrounding soil and flexible pipes with a fully bonded pipe-soil interface provides a reasonable prediction for soil pressures close to the buried pipes.
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Date Issued: 2006
PURL: http://purl.flvc.org/fau/fd/FA00012573
Subject Headings: Structural analysis (Engineering), Pipe, Plastic--Dynamics--Mathematical models, Underground pipelines--Design and construction, Soil-structure interaction
Format: Document (PDF)

Title: Studies of composite multihull ship structures using fluid structure interaction.
Creator: Ma, Siyuan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Studies of composite multihull structure under wave loads, extreme loads, and blast loads have been conducted using finite element and computational fluid dynamics (CPF) tools. A comprehensive finite element tool for structural analysis of composite multi-hull structures is developed. Two-way fluid structure interaction (FSI) is implemented by coupling finite element analysis (FEA) and CFD. FEA models have been developed using sandwich construction having composite face sheets and a foam core...
Show moreStudies of composite multihull structure under wave loads, extreme loads, and blast loads have been conducted using finite element and computational fluid dynamics (CPF) tools. A comprehensive finite element tool for structural analysis of composite multi-hull structures is developed. Two-way fluid structure interaction (FSI) is implemented by coupling finite element analysis (FEA) and CFD. FEA models have been developed using sandwich construction having composite face sheets and a foam core. Fluid domain was modeled using the CFD code, CFX and a wave motion was simulated based on Sea State 5... In addition to hydrodynamic loads, the simulation of composite ship under extreme loads is performed. Stress analysis was performed and dynamic response of the hull was determined in time domain. In the final analysis, an underwater explosion model was developed to study the composite hull resistance to blast load.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3355625
Subject Headings: Computational fluid dynamics, Numerical analysis, Engineering mathematics, Naval architecture, Structural analysis (Engineering)
Format: Document (PDF)

Title: Reliability-based fatigue design of marine current turbine rotor blades.
Creator: Hurley, Shaun., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: The study presents a reliability-based fatigue life prediction model for the ocean current turbine rotor blades. The numerically simulated bending moment ranges based on the measured current velocities off the Southeast coast line of Florida over a one month period are used to reflect the short-term distribution of the bending moment ranges for an idealized marine current turbine rotor blade. The 2-parameter Weibull distribution is used to fit the short-term distribution and then used to...
Show moreThe study presents a reliability-based fatigue life prediction model for the ocean current turbine rotor blades. The numerically simulated bending moment ranges based on the measured current velocities off the Southeast coast line of Florida over a one month period are used to reflect the short-term distribution of the bending moment ranges for an idealized marine current turbine rotor blade. The 2-parameter Weibull distribution is used to fit the short-term distribution and then used to obtain the long-term distribution over the design life. The long-term distribution is then used to determine the number of cycles for any given bending moment range. The published laboratory test data in the form of an ε-N curve is used in conjunction with the long-term distribution of the bending moment ranges in the prediction of the fatigue failure of the rotor blade using Miner's rule. The first-order reliability method is used in order to determine the reliability index for a given section modulus over a given design life. The results of reliability analysis are then used to calibrate the partial safety factors for load and resistance.
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Date Issued: 2011
PURL: http://purl.flvc.org/FAU/3183123
Subject Headings: Turbines, Blades, Materials, Fatigue, Marine turbines, Mathematical models, Composite materials, Mathematical models, Structural dynamics
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 energy-based 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 energy-based 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 energy-based 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 space-wise and time-wise white noise excitations. Finally, the new energy-based 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 dynamics--Mathematical models, Vibration--Mathematical models
Format: Document (PDF)

Title: Experimental determination of motion-induced force coefficients of long-span bridge models in a water channel.
Creator: Wei, Li., Florida Atlantic University, Su, Tsung-Chow, 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 self-excited loads. The research reported in this thesis is concerned with experimental determination of the self-excited loads in the frequency domain, in particular, their non-dimensional coefficients, called flutter derivatives. The experiments were conducted in a water channel with water substituting for air. Five bridge-section 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 self-excited loads. The research reported in this thesis is concerned with experimental determination of the self-excited loads in the frequency domain, in particular, their non-dimensional coefficients, called flutter derivatives. The experiments were conducted in a water channel with water substituting for air. Five bridge-section 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 thin-plate 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, Long-span, Wind-pressure, Bridges--Vibration, Structural dynamics
Format: Document (PDF)

Title: Finite element analysis of the visco-elastic behavior of a spray ice island.
Creator: Thiel, David Ted., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis presents a finite element analysis of the viscoelastic (creep) behavior of a spray ice island under its own self-weight and three levels of lateral loads. Spray ice and its use as a construction material are described in the context of other natural ice forms and the ice environment of the Beaufort Sea. The analytical results indicated that creep settlement in the absence of volumetric contraction was nominal over the course of a simulated 21-day construction period and a 79-day...
Show moreThis thesis presents a finite element analysis of the viscoelastic (creep) behavior of a spray ice island under its own self-weight and three levels of lateral loads. Spray ice and its use as a construction material are described in the context of other natural ice forms and the ice environment of the Beaufort Sea. The analytical results indicated that creep settlement in the absence of volumetric contraction was nominal over the course of a simulated 21-day construction period and a 79-day service life. The effects of the applied lateral loads were very localized and did not result in any appreciable deformations in the central working area of the structure. Some evidence of shear plane development and upward passive failure of the island perimeter was observed.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/14647
Subject Headings: Ice mechanics, Offshore structures--Dynamics, Sea ice--Beaufort Sea
Format: Document (PDF)

Title: Mobility power flow analysis of an infinite cylindrical shell with an enclosed plate discontinuity.
Creator: Buchmann, Patrick Pierre., Florida Atlantic University, Cuschieri, Joseph M.
Abstract/Description: A mobility power flow approach is used to study the response of an infinitely-long cylindrical shell with an internal plate discontinuity. The shell is excited by either a ring radial force or by a plane acoustic wave. The junction between the shell and the internal plate is assumed to be radially pinned such that in-plane waves of the plate can be neglected. The junction forces are expressed in terms of the mobility functions of the plate and the shell. From knowledge of the junction forces...
Show moreA mobility power flow approach is used to study the response of an infinitely-long cylindrical shell with an internal plate discontinuity. The shell is excited by either a ring radial force or by a plane acoustic wave. The junction between the shell and the internal plate is assumed to be radially pinned such that in-plane waves of the plate can be neglected. The junction forces are expressed in terms of the mobility functions of the plate and the shell. From knowledge of the junction forces and velocities, the power input, the power flow from the shell to the plate, the shell response and the radiated far-field scattered pressure are determined for the circumferential mode n = 0. The results show how the energy propagates from one structure to the other, and present a very clear picture of the characteristics of the scattering pattern from the junction forces.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15113
Subject Headings: Shells (Engineering)--Vibration, Plates (Engineering)--Vibration, Structural dynamics, Vibration
Format: Document (PDF)

Title: Modeling and control of a vertically tethered marine platform using an active heave compensation system.
Creator: Eide, Linn., Florida Atlantic University, Driscoll, Frederick R.
Abstract/Description: Technology movement toward deeper waters necessitates the control of vertically tethered systems that are used for installing, repairing, and maintaining underwater equipment. This has become an essential ingredient for the future success of the oil industry as the near-shore oil reservoirs are nearly depleted. Increased operation depths cause large oscillations and snap loadings in these longer cables. Research on this topic has been limited, and includes only top feedback control. The...
Show moreTechnology movement toward deeper waters necessitates the control of vertically tethered systems that are used for installing, repairing, and maintaining underwater equipment. This has become an essential ingredient for the future success of the oil industry as the near-shore oil reservoirs are nearly depleted. Increased operation depths cause large oscillations and snap loadings in these longer cables. Research on this topic has been limited, and includes only top feedback control. The controllers developed in this thesis utilize top, bottom and combined top and bottom feedback. They are implemented on a discrete finite element lumped mass cable model. Comparison between PID, LQG and H infinity for all feedback combinations reveal that the Hinfinity controller with both top and bottom feedback has the best performance, while LQG has a more consistent and reliable performance for all feedback cases.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13079
Subject Headings: Cables, Submarine--Mathematical models, Offshore structures--Dynamics, Feedback control systems, Ships--Hydrodynamics
Format: Document (PDF)

Title: Fatigue modeling of composite ocean current turbine blade.
Creator: Akram, Mohammad Wasim, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The success of harnessing energy from ocean current will require a reliable structural design of turbine blade that is used for energy extraction. In this study we are particularly focusing on the fatigue life of a 3m length ocean current turbine blade. The blade consists of sandwich construction having polymeric foam as core, and carbon/epoxy as face sheet. Repetitive loads (Fatigue) on the blade have been formulated from the randomness of the ocean current associated with turbulence and...
Show moreThe success of harnessing energy from ocean current will require a reliable structural design of turbine blade that is used for energy extraction. In this study we are particularly focusing on the fatigue life of a 3m length ocean current turbine blade. The blade consists of sandwich construction having polymeric foam as core, and carbon/epoxy as face sheet. Repetitive loads (Fatigue) on the blade have been formulated from the randomness of the ocean current associated with turbulence and also from velocity shear. These varying forces will cause a cyclic variation of bending and shear stresses subjecting to the blade to fatigue. Rainflow Counting algorithm has been used to count the number of cycles within a specific mean and amplitude that will act on the blade from random loading data. Finite Element code ANSYS has been used to develop an S-N diagram with a frequency of 1 Hz and loading ratio 0.1 Number of specific load cycles from Rainflow Counting in conjunction with S-N diagram from ANSYS has been utilized to calculate fatigue damage up to 30 years by Palmgren-Miner's linear hypothesis.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2867332
Subject Headings: Turbines, Blades, Materials, Fatigue, Marine turbines, Mathematical models, Structural dynamics, Composite materials, Mathematical models, Sandwich construction, Fatigue
Format: Document (PDF)

Title: Design and analysis of hybrid titanium-composite hull structures under extreme wave and slamming loads.
Creator: Rahman, Md Hafizur, Mahfuz, Hassan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A finite element tool has been developed to design and investigate a multi-hull composite ship structure, and a hybrid hull of identical length and beam. Hybrid hull structure is assembled by Titanium alloy (Ti-6Al-4V) frame and sandwich composite panels. Wave loads and slamming loads acting on both hull structures have been calculated according to ABS rules at sea state 5 with a ship velocity of 40 knots. Comparisons of deformations and stresses between two sets of loadings demonstrate that...
Show moreA finite element tool has been developed to design and investigate a multi-hull composite ship structure, and a hybrid hull of identical length and beam. Hybrid hull structure is assembled by Titanium alloy (Ti-6Al-4V) frame and sandwich composite panels. Wave loads and slamming loads acting on both hull structures have been calculated according to ABS rules at sea state 5 with a ship velocity of 40 knots. Comparisons of deformations and stresses between two sets of loadings demonstrate that slamming loads have more detrimental effects on ship structure. Deformation under slamming is almost one order higher than that caused by wave loads. Also, Titanium frame in hybrid hull significantly reduces both deformation and stresses when compared to composite hull due to enhancement of in plane strength and stiffness of the hull. A 73m long hybrid hull has also been investigated under wave and slamming loads in time domain for dynamic analysis.
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Date Issued: 2013
PURL: http://purl.flvc.org/fau/fd/FA0004048
Subject Headings: Hulls (Naval architecture) -- Design and construction, Ships -- United States -- Design and construction, Structural dynamics, Water waves -- Mathematical models
Format: Document (PDF)

Title: Permanent strain accumulation in a granular material due to cyclic loading.
Creator: Genduso, Michael J., Florida Atlantic University, Sobhan, Khaled Dr.
Abstract/Description: To better characterize the accumulation of permanent deformation in a granular material, 40 Consolidated Drained (CD) triaxial tests (14 static and 26 cyclic) were performed under various stress conditions. A Digital Image Correlation (DIC) technique was utilized in some Repeated Load Triaxial (RLT) tests to measure global and localized strains visually in a non-contact manner. Additionally, the experimentally determined resilient material properties were used in a finite element based...
Show moreTo better characterize the accumulation of permanent deformation in a granular material, 40 Consolidated Drained (CD) triaxial tests (14 static and 26 cyclic) were performed under various stress conditions. A Digital Image Correlation (DIC) technique was utilized in some Repeated Load Triaxial (RLT) tests to measure global and localized strains visually in a non-contact manner. Additionally, the experimentally determined resilient material properties were used in a finite element based pavement modeling software called MICH-PAVE. Under cyclic loading, the permanent strain accumulation was found to obey the relationship of the form epsilonp =aNb, and the Resilient Modulus was used to develop the nonlinear K-theta model for granular materials. The observed/measured permanent strains using DIC/LVDT techniques compared favorably with the values obtained by the finite element simulation, and the evaluation of granular material by multiple methods seems promising for improved pavement design.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/13264
Subject Headings: Soils--Testing, Soil mechanics, Soil-structure interaction, Engineering geology, Rocks--Testing, Materials--Dynamic testing
Format: Document (PDF)

Title: Design and Deployment Analysis of Morphing Ocean Structure.
Creator: Li, Yanjun, Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: As humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more...
Show moreAs humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more efficient deployment of marine structures. Deployable structures are able to be compacted and transported via AUV to their destination then morph into their final form upon arrival. They are a lightweight, compact solution. The wrapped package includes the deployable structure, underwater pump, and other necessary instruments, and the entire package is able to meet the payload capability requirements. Upon inflation, these structures can morph into final shapes that are a hundred times larger than their original volume, which extends the detection range and also provides long-term observation capabilities. This dissertation reviews underwater platforms, underwater acoustics, imaging sensors, and inflatable structure applications then proposes potential applications for the inflatable structures. Based on the proposed applications, a conceptual design of an underwater tubular structure is developed and initial prototypes are built for the study of the mechanics of inflatable tubes. Numerical approaches for the inflation process and bending loading are developed to predict the inflatable tubular behavior during the structure’s morphing process and under different loading conditions. The material properties are defined based on tensile tests. The numerical results are compared with and verified by experimental data. The methods used in this research provide a solution for underwater inflatable structure design and analysis. Several ocean morphing structures are proposed based on the inflatable tube analysis.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004752, http://purl.flvc.org/fau/fd/FA00004752
Subject Headings: Air-supported structures--Design and construction., Remote submersibles--Design and construction., Tensile architecture., Fluid mechanics., Structural dynamics., Ocean engineering., Adaptive control systems.
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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