Mechanical Engineering Commons^™

The Risk Mitigation Strategy Taxonomy And Generated Risk Event Effect Neutralization Method, Daniel A. Krus

Doctoral Dissertations

"In the design of new products and systems, the mitigation of potential failures is very important. The sooner in a product's design mitigation can be performed, the lower the cost and easier to implement those mitigations become. However, currently, most mitigations strategies rely on the expertise of the engineers designing a product, and while models and for failure modes do exist to help, there are no guidelines for performing product changes to reduce risk. To help alleviate this, the risk mitigation strategy taxonomy is created from an empirical collection of mitigation strategies used in industry for failure mitigation, creating a …

Electrospun Carbon Nanofibers Decorated With Various Amounts Of Electrochemically-Inert Nickel Nanoparticles For Use As High-Performance Energy Storage Materials, Liwen Ji, Zhan Lin, Mataz Alcoutlabi, Ozan Toprakci, Yingfang Yao, Guanjie Xu, Shuli Li, Xiangwu Zhang

Mechanical Engineering Faculty Publications

Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanoparticles are synthesized through electrospinning and carbonization processes. The morphology and composition of Ni nanoparticles in carbon nanofibers are controlled by preparing different nanofiber precursors. The lithium-ion battery performance evaluations indicated that the content of electrochemically-inert Ni nanoparticles in carbon nanofibers has a great influence on the final electrochemical performance. For example, at certain Ni contents, these composite nanofibers display excellent electrochemical performance, such as high reversible capacities, good capacity retention, and excellent rate performance, when directly used as binder-free anodes for rechargeable lithium-ion batteries. However, when the Ni content …

Passive Gas-Liquid Separation Using Hydrophobic Porous Polymer Membranes: A Study On The Effect Of Operating Pressure On Membrane Area Requirement, Taylor Patrick Maxwell

UNF Graduate Theses and Dissertations

The use of hydrophobic porous polymer membranes to vent unwanted gas bubbles from liquid streams is becoming increasingly more common in portable applications such as direct methanol fuel cells (DMFCs) and micro-fluidic cooling of electronic circuits. In order for these portable systems to keep up with the ever increasing demand of the mobile user, it is essential that auxiliary components, like gas-liquid separators (GLS), continue to decrease in weight and size. While there has been significant progress made in the field of membrane-based gas-liquid separation, the ability to miniaturize such devices has not been thoroughly addressed in the available literature. …

Development Of A Predictive Model For Bulk-Flow Through A Porous Polymer Membrane Tube, Aaron Robert Meles

UNF Graduate Theses and Dissertations

While extensive mathematical and numerical work has been done in terms of modeling the mainstream flow in a tube with porous walls, very little has been done experimentally to confirm these various solutions, and what has been done has focused on large sintered metal tubes used in nuclear power applications. Furthermore, these solutions are quite mathematically complex and arduous to implement. In this work, the mainstream flow through a porous polymer membrane tube is examined and a method for calculating the through-membrane flow rate and axial pressure drop is presented. Two membrane tubes are tested experimentally, and a simple set …

Silk Cryogels For Microfluidics, Christopher David Hinojosa

Dissertations and Theses

Silk fibroin from silkworm cocoons is found in numerous applications ranging from textiles to medical implants. Its recent adoption as a biomaterial is due to the material's strength, biocompatibility, self-assembling behavior, programmable degradability, optical clarity, and its ability to be functionalized with antibodies and proteins. In the field of bioengineering it has been utilized as a tissue scaffolding, drug delivery system, biosensor, and implantable electrode. This work suggests a new application for porous silk in a microscale chromatography column. We demonstrate in situ cryotropic polymerization of highly porous structures in microscale geometries by freezing aqueous silk with a solvent. The …

Development Of A Robotic Platform For Upper Limb Rehabilitation, Stephen Curran, Nigel Kent, David Kennedy, James Conlon

Conference Papers

The aim of this project is to develop a rehabilitation robot intended for use in a non-specialised or domestic setting. Robots have been shown to have a positive effect on limb rehabilitation and developing rehabilitation robots for use outside of specialist rehabilitation centres could be beneficial in terms of access to, intensity and cost of treatment. The device is intended for the rehabilitation of the shoulder/elbow region of the upper limbs. The design requirements for such a device mean that it must be low cost, portable, robust and have a detailed focus on safety. Other areas of interest pertaining to …

Stability Problems In Constrained Pendulum Systems And Time-Delayed Systems, Prashanth Ramachandran

LSU Doctoral Dissertations

In this dissertation, we study the boundary of stability of a class of linear mechanical systems as a function of a parameter. We consider two different systems under this class: a constrained double pendulum connected by a rigid rod and a state-feedback-controlled mechanical system with time delay. In the first system, the destabilizing parameter is the distance between the supports of the two pendulums. In the second system, the destabilizing parameter is the time delay. In the constrained double pendulum system, linear perturbation analysis is used to determine the natural frequency of the system. Our analysis reveals a zone of …

Numerical And Experimental Evaluation Of Preheated Premixed Flames At Lean And Rich Conditions, Joseph Edward Gibson

LSU Master's Theses

Preheating a combustible mixture enhances the laminar burning flux characteristic m_ad with high reaction firing rates. As a result, the flammable zone as defined by inlet conditions of equivalence ratio and temperature is expanded beyond that available at standard ambient conditions; however, fundamental questions in these combustion regimes have not been addressed. In this thesis, preheated lean and rich combustion of methane/air mixtures is studied numerically and experimentally to catalog and confirm expected trends in these regimes. Numerical simulations were completed using both GRI-Mech 3.0 and San Diego mechanisms in the combustion code Cantera. An adiabatic simulation data set …

Modeling Of Dynamics Of Gyroscopic Systems, Siddharth Sharma

LSU Master's Theses

The amplitude of vibrations of a rotating system operating near or at its critical speed grows without bound. This poses a serious problem for the rotating machinery industry from the perspective of design, maintenance, vibration troubleshooting and stability of the rotating equipments.

In this thesis, we wish to develop an exact method of analysis for the system of a mass-less symmetrical shaft rotating in symmetrical bearings (SSSB) with finite displacement at bearing end. The method so developed is expected to be extended to the SSSB model of a shaft having mass. The stability analysis is performed for both the systems. …

Bucky Gel Actuator For Morphing Applications, Ali Kadkhoda Ghamsari

LSU Doctoral Dissertations

Since the demonstration of Bucky Gel Actuator (BGA) in 2005, a great deal of effort has been exerted to develop novel applications for electro-active morphing materials. Three-layered bimorph nanocomposite has become an excellent candidate for morphing applications since it can be easily fabricated, operated in air, and driven with few volts. There has been limited published study on the mechanical properties of BGA. In this study, the effect of three parameters: layer thickness, carbon nanotube type, and weight fraction of components, on the mechanical properties was investigated. Samples were characterized via nano-indentation and DMA. It was found that BGA composed …

Multifunctional Carbon/Epoxy Glass Microballons Nanocomposite, Ephraim Fentahun Zegeye

LSU Doctoral Dissertations

Glass microballoons have high strength, low thermal and electrical properties, and provide closed cell porosity to reduce the density of composites. On the other hand, filamentous carbon nanostructures have excellent mechanical, thermal, and electrical properties that make them naturally multifunctional. This work presents a method of developing low-density multifunctional nanocomposites utilizing glass microballoons and carbon nanostructures. Two different approaches are investigated. In the first approach, carbon nanotubes (CNTs) are used as a filler material to fabricate nanocomposites containing glass microballoons (CNT-syntactic foams). The weight percent of CNTs is varied from 0 to 0.8 wt%. In this method, CNTs were grown …

Multiscale Viscoplastic-Viscodamage Analysis Of Shape Memory Polymer Fibers With Application To Self Healing Smart Materials, Amir Shojaei

LSU Doctoral Dissertations

Self-healing smart material systems have been introduced into the research arena and they have already been deployed into industrial applications. The Close-Then-Heal (CTH) healing mechanism for polymeric self-healing systems is addressed herein and then a new generation of Shape Memory Polymer (SMP) based self-healing system is proposed in this work. This system incorporates SMP fibers to close the cracks while the embedded Thermoplastic Particles (TPs) are diffused into the crack surfaces upon heating and provide a molecular level of healing. The SMP fiber manufacturing procedure is briefly addressed in this work in which the bobbin of SMP fibers are heat …

Pdms Based Waveguides For Microfluidics And Eocb, Weiping Qiu

LSU Master's Theses

Due to the low cost, fast and ease of molding, PDMS has become one of the most popular materials for microfluidics devices, bioMEMS applications. Meanwhile, the integration of different functional components on to one single chip (or Lab on a Chip) is the dream for many scientists and engineers in the related area. In addition to the necessary mechanical components for accommodating the reactions, such as pumps, valves, mixers and so on, optical components such as waveguides, lens, interferers are all desired to be lumped into such a system.

The waveguide for such a system requires the material to have …

Multistable Shape-Shifting Surfaces (Mssss), Paul Joseph Montalbano

USF Tampa Graduate Theses and Dissertations

This paper presents designs for Multistable Shape-Shifting Surfaces (MSSS) by introducing bistability into the Shape-Shifting Surface (SSS). SSSs are defined as surfaces that retain their effectiveness as a physical barrier while undergoing changes in shape. The addition of bistability to the SSS gives the surface multiple distinct positions in which it remains when shifted to, i.e. by designing bistability into a single SSS link, the SSS unit cell can change into multiple shapes, and stabilize within the resulting shape, while maintaining integrity against various forms of external assaults normal to its surface. Planar stable configurations of the unit cell include, …

A Statically Balanced Shape-Shifting Surface, Joseph Eugene Pishnery

USF Tampa Graduate Theses and Dissertations

ABSTRACT

This paper presents a concept for producing a Statically Balanced Shape-Shifting Surface (SB-SSS). In this context, an SB-SSS is a surface that can require near-zero magnitude force changes to accomplish a change in shape while retaining effectiveness as a physical barrier. This paper focuses on how to statically balance a specifically-designed compliant mechanism and how to incorporate this mechanism into a polygonal cell.

The mechanism consists of a compliant Peaucellier-Lipkin linkage layered with a pre-stressed link as the balancer. Previous work is presented that can show how a polygonal cell can be incorporated into a surface via a tiling …

Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall

USF Tampa Graduate Theses and Dissertations

Fish sound production has been associated with courtship and spawning behavior. Acoustic recordings of fish sounds can be used to identify distribution and behavior. Passive acoustic monitoring (PAM) can record large amounts of acoustic data in a specific area for days to years. These data can be collected in remote locations under potentially unsafe seas throughout a 24-hour period providing datasets unattainable using observer-based methods. However, the instruments must withstand the caustic ocean environment and be retrieved to obtain the recorded data. This can prove difficult due to the risk of PAMs being lost, stolen or damaged, especially in highly …

Effects Of Random Cross-Sectioned Distributions, Fiber Misalignment And Interphases In Three-Dimensional Composite Models On Transverse Shear Modulus, Jarrett Zitko

USF Tampa Graduate Theses and Dissertations

Finite element analysis was implemented to evaluate the transverse shear modulus of a unidirectional glass/epoxy fiber-matrix composite based on pure shear displacement boundary conditions. Unit cells consisting of three-dimensional glass cylinders surrounded in square-cuboid epoxy matrices were modeled to represent "Representative Volume Element" (RVE) configurations in periodic and random-periodic square cell arrangements of variable size. Three RVEs were constructed and analyzed: A single unit cell, a 9-cell (3 x 3) array, and a 25-cell (5 x 5) array. Additionally, the unit cell was modeled to include an interphase. Three sets of cell arrangements were constructed and evaluated: a periodic square …

Chemical Mechanical Planarization Of Electronic Materials, Fnu Atiquzzaman

USF Tampa Graduate Theses and Dissertations

In the modern semiconductor manufacturing processes, chemical mechanical planarization (CMP) has attained important processing step because of its ability to provide global planarization. CMP is the planarization technique which is used for the removal of excess material, as left over from the previous processing steps. In addition, CMP offers a uniform surface that is essential for subsequent processing steps, especially for the high resolution photolithography processes. In simpler notation, CMP is a process where a chemical reaction enhances in obtaining a planar surface through removal of the mechanical materials from a wafer.

In this study, CMP performance of three electronic …

Design Of Contact Line Friction Measurement Machine Apparatus, Seyed Kamran Najafi

USF Tampa Graduate Theses and Dissertations

The purpose of this project is to design and manufacture a high precision machine to directly measure the surface force of fluids. Knowing how to move droplets easier with less resistance can increase the potential of a wide range of applications and improve the performance of things such as self-assembly applications. This machine has the ability to measure forces of up to 100 N with a MEMS based sensor. The motion system on this machine moves a substrate underneath of a droplet for 100 mm and applies dragging force to the sensor. It moves with a controlled speed with high …

Dolphin Sound Production And Distribution On The West Florida Shelf, Peter Simard

USF Tampa Graduate Theses and Dissertations

This dissertation is an investigation of dolphin sound production and distribution off west central Florida. Although a wealth of information exists on the production of common sounds (whistles, echolocation) made by captive, trained dolphins, far less is known about free-ranging dolphin sound production and of unusual sounds. In addition, while inshore dolphin populations or communities are the subjects of research projects in many locations, dolphins in offshore waters are less commonly studied. The objectives of this dissertation were to contribute information on free-ranging dolphin sounds and continental shelf dolphin distribution.

While echolocation has been rigorously studied in captive, trained dolphins, …

Prevailing Torque Locking Feature Wear-Out, Adam Joseph Charles Zimandy

USF Tampa Graduate Theses and Dissertations

This thesis provides much needed representative sample data for reuse life of fully seated and torqued locknuts. Most national requirements for prevailing torque locking fasteners only specify unseated reuse life. This could create a potentially dangerous situation if unseated is misinterpreted for seated. This thesis provides comparative data for seated verses unseated configuration. Six aerospace, 3 all-metal and 3 nylon insert, and one non-aerospace locknuts were tested at preloads levels of unseated, 66%, 75%, and 85% of yield of bolt. The locknuts tested are MS21043-4, NAS1291-4, NAS1805-4, MS17825-4, MS21044D4, NAS1021N4, and Grade 8. A fixture was created in order to …

Direct Verification Of The Locking Of Liquid Locking Compounds In Threaded Fasteners, Ryan Hunter

USF Tampa Graduate Theses and Dissertations

The motivation of this research is to explore the viability of a method to directly verify whether or not an anaerobic adhesive within a threaded fastener assembly has cured sufficiently to provide secondary locking. Direct verification was implemented via the application of a test torque in the loosening direction of a fastener assembly with Loctite (given a 24 hour cure time). A three phase test plan was developed with the intent of identifying and utilizing this verification torque value which is unique to a given fastener assembly.

It was proved that the direct verification method, as outlined in the test …

High Tech High Touch: Lessons Learned From Project Haiti 2011, Yan Tang, Marc Compere, Yung Lun Wong, Jared Anthony Coleman, Matthew Charles Selkirk

Publications

In this paper, we will share our experiences and lessons learned from a design project for providing clean water to a Haitian orphanage (Project Haiti 2011). Supported by funds from a renewable energy company and the university president’s office, five engineering students and two faculty members from Embry-Riddle Aeronautical University successfully designed and installed a solar powered water purification system for an orphanage located in Chambellan, Haiti. This paper discusses the unique educational experiences gained from unusual design constraints, such as ambiguity of existing facilities due to limited communication, logistics of international construction at a remote village location, and cross-cultural …

Multi-Disciplinary Hands-On Desktop Learning Modules And Modern Pedagogies, Bernard J. Van Wie, David B. Thiessen, Marc Compere, Ximena Toro, Jennifer C. Adam, Et Al.

Publications

Our team’s research focuses on fundamental problems in undergraduate education in terms of how to expand use of well researched, yet still “new”, teaching pedagogies of ‘sensing’ or ‘hands-on’, ‘active’ and ‘problem-based learning’ within engineering courses. It is now widely accepted that traditional lectures ARE NOT best for students – yet that is what the community almost universally does.

To address this issue we are developing new Desktop Learning Modules (DLMs) that contain miniaturized processes with a uniquely expandable electronic system to contend with known sensor systems/removable cartridges, as well as, unknown expansions to the project. We have shown that …

A Material System For Reliable Low Voltage Anodic Electrowetting, Mehdi Khodayari, Jose Carballo, Nathan B. Crane

Faculty Publications

Electrowetting on dielectric is demonstrated with a thin spin-coated fluoropolymer over an aluminum electrode. Previous efforts to use thin spin-coated dielectric layers for electrowetting have shown limited success due to defects in the layers. However, when used with a citric acid electrolyte and anodic voltages, repeatable droplet actuation is achieved for 5000 cycles with an actuation of just 10 V. This offers the potential for low voltage electrowetting systems that can be manufactured with a simple low-cost process.

Ballistic Imaging Of Sprays At Diesel Relevant Conditions, Jason M. Porter, S. P. Duran, T. E. Parker

Faculty Publications

Diesel engines are an important aspect of our transportation infrastructure, whose performance is greatly affected by the characteristics of the spray from their injectors. Characterization of the injector’s spray is therefore tantamount to clean-running efficient diesel motors. In this study, a ~15 ps pulsed Leopard D-10 laser is used along with an optical Kerr Cell to realize ballistic images of high-delivery-pressure dodecane sprays injected into a quiescent air environment at elevated temperature and pressure. Using CS2 as the Kerr switching media and by optimizing the overlap of the gate and imaging beams, an effective high speed shuttering effect is obtained. …

Large-Eddy Simulation Of Axially-Rotating, Turbulent Pipe And Particle-Laden Swirling Jet Flows, Nicolas D. Castro

Mechanical & Aerospace Engineering Theses & Dissertations

The flows of fully-developed turbulent rotating pipe and particle-laden swirling jet emitted from the pipe into open quiescent atmosphere are investigated numerically using Large-Eddy Simulation (LES). Simulations are performed at various rotation rates and Reynolds numbers, based on bulk velocity and pipe diameter, of 5.3x103, 12x103, and 24x103, respectively. Time-averaged LES results are compared with experimental and simulation data from previous studies. Pipe flow results confirm observations in previous studies, such as the deformation of the turbulent mean axial velocity profile towards the laminar Poiseuille-profile, with increased rotation. The Reynolds stress anisotropy tensor shows a redistribution due to pipe rotation. …