Mechanical Engineering Commons^™

The Effect Of Microencapsulated Phase-Change Material On The Compressive Strength Of Structural Concrete, Chad Norvell, David J. Sailor, Peter Dusicka

Mechanical and Materials Engineering Faculty Publications and Presentations

Latent heat energy storage through phase-change materials (PCMs) is one possible strategy to control interior temperatures in buildings, improve thermal comfort, and passively reduce building energy use associated with heating and cooling. While PCMs integrated into building structure elements have been studied since the 1970s, challenges of integrating PCMs into building materials while maintaining their heat storage benefits have limited their application in practice. The recent introduction of microencapsulated phase-change materials provides the energy storage capability of PCMs in micron-scale, chemically-inert capsules that can be easily integrated into composite materials such as gypsum wallboard and concrete. The size and physical …

Heating Effects Through Harmonic Distortion On Electric Cables In The Built Environment, Kevin O'Connell

Doctoral

Under ideal circumstances, electric power supply voltage and current waveforms should be sinusoidal. However, this is very seldom the case in the built environment, due to the proliferation of non-linear loads. Examples of non-linear loads are those containing switched mode power supplies, reactors and electronic rectifiers/inverters. Common devices such as personal computers, fluorescent lighting, electric motors, variable speed drives, transformers and reactors and virtually all other electronic equipment are examples of non-linear loads. Non-linear loads are the norm in the built environment rather than the exception. Such loads produce complex current and voltage waves and simple spectral analysis of these …

Dynamic Modeling Of A Belt Driven Electromechanical Xy Plotter Cutter, Joseph V. Prisco

Master's Theses (2009 -)

Current industrial XY plotter cutters that use a belt driven gantry for the X motion and media feed for the Y motion sometimes have performance issues in cutting out high quality shapes. Mathematical models for these plotter cutters are not publicly available and thus the parameters critical to cut quality are not well understood. This thesis develops a dynamic, electromechanical model for the gantry arm and media feed using first principles and a non-linear friction model. These models are independently simulated and experimentally verified. In order to verify the effectiveness of the individual models, they are combined with a control …

Flame Temperature Imaging Of A Low Nox Burner Via Laser Rayleigh Scattering, Nicholas A. Smith

Master's Theses (2009 -)

Federal and global legislation are requiring increasingly stringent emission regulation on household appliances and in particular water heater burners. Emissions like NOx (NO and NO2) are a growing concern due to their adverse health effects and contribution to tropospheric ozone, acid rain, and smog formation. As NOx is more closely controlled, appliance manufacturers are developing low emission burners for use in water heaters.

Flame temperature is strongly correlated to NOx production. Hence, characterizing flame temperatures in new burners is a key part of improving upon burners used today and the development of future burners. Temperature measurements applied to a new, …

Preliminary Development Of A Subject Specific Finite Element Model Of The Hindfoot, Liang Dong

Mechanical & Aerospace Engineering Theses & Dissertations

The human hindfoot is a complex structure and its medical treatment can vary from patient to patient. If physicians have access to a patient specific computer model, the optimal treatment option can be explored on the model before preforming it on the patient. The purpose of this study was to create a quasi-static finite element model and to show the stress contour in the cartilage between the bones. Ankle joint contact pressure was collected on one cadaver limb with a 40 lbs ( 178 N) axial load applied and tendon loads applied to simulate the ratio of tendon loading during …

Microphone-Based Pressure Diagnostics For Boundary Layer Transition, Spencer Everett Lillywhite

Master's Theses

An experimental investigation of the use low-cost microphones for unsteady total pressure measurement to detect transition from laminar to turbulent boundary layer flow has been conducted. Two small electret condenser microphones, the Knowles FG-23629 and the FG-23742, were used to measure the pressure fluctuations and considered for possible integration with an autonomous boundary layer measurement system. Procedures to determine the microphones’ maximum sound pressure levels and frequency response using an acoustic source provided by a speaker and a reference microphone. These studies showed that both microphones possess a very flat frequency response and that the max SPL of the FG-23629 …

Multi-Objective Preliminary Design Optimization Of Planing Craft Using Differential Evolution And Artificial Networks, Robert Eugene Weidman

Mechanical & Aerospace Engineering Theses & Dissertations

The differential evolution (DE) algorithm is an evolutionary algorithm that has been utilized as a metaheuristic optimizer in the last few years. A recently developed multi-objective version of DE is utilized in this research in order to optimize the preliminary design of planing craft. The craft performance is evaluated using the planing hull preliminary design software PHAST. The optimization problem objectives are the craft acquisition cost and the overall measure of effectiveness; the latter comprises various performance aspects: ride quality, transportability, payload, and mobility. Static stability and operating constraints are also considered. Each of the aforementioned four measures of effectiveness …

Field Emission Studies Toward Improving The Performance Of Dc High Voltage Photoelectron Guns, Mahzad Bastaninejad

Mechanical & Aerospace Engineering Theses & Dissertations

Field emission is the main mechanism that prevents DC high voltage photoemission electron guns from operating at the very high bias voltages required to produce low emittance beams. Gas conditioning is shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. The field emission characteristics of 5 stainless steel electrodes varied significantly upon the initial application of voltage but improved to nearly the same level …

Static And Vibration Analyses, And Sensitivity Analysis Of Stepped Beams Using Singularity Functions, Carla Rocio Davila

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis intends to prove that singularity functions can be used to perform static and vibration analyses and their sensitivity analysis of stepped beams subjected to various support constraints. Specifically, this thesis develops formulations using singularity functions for static and vibration analyses of a simply-supported, a roller­ supported, and a spring-supported stepped beam. The Static and Vibration Sensitivity Analysis formulations are derived for the simply-supported beam to show the feasibility of this approach. The techniques presented in this thesis can be extended to various other supports constraints such as a middle support, and spring support or any other variation of …

Development And Assessment Of An In-Situ Load System, Kenneth Toro

Mechanical & Aerospace Engineering Theses & Dissertations

The In-situ Load System (ILS) was designed at NASA Langley Research Center (LaRC) to perform multi-component check loads on a force balance at a test facility. The ILS is designed to allow a force balance to be placed at off nominal orientations, while maintaining an applied load in the gravitational direction. This allows for multicomponent loads to be applied to a balance as a function of balance orientation and ILS configuration. The system is designed to be used in conjunction with a facilities existing pitch and roll control systems.

The ILS was modified to provide higher load ranges than those …

Improvement Of Hydraulic Press For Vegetable Oil Expression In Rural Areas, I. P. Bateebe

Tanzania Journal of Engineering and Technology (TJET)

Cultivation of oil producing crops especially Jatropha and croton as source of vegetable oil for biodiesel production is being encouraged in rural areas. To recover oil from seed, manual press is the feasible method in rural areas where there is no electricity. Research was conducted to improve hydraulic oil press machine for rural application. Factors affecting oil recovery were found to be: moisture content of seeds, operating pressure, seed oil content, and the amount of seeds pressed per batch. Percentage oil recovery was improved by reducing diameter of press cylinder, hence increasing expression pressure, and either reducing amount of seed …

Investigation Of Thermal Properties And Latent Heat Reduction Mechanisms In Nanofluid Phase Change Materials, Aitor Zabalegui

Mechanical Engineering Master's Theses

The thermal properties of paraffin-based nanofluids have been examined to investigate the use of enhanced phase change materials (PCMs) for thermal energy storage (TES). PCMs are promising for TES applications, but low thermal conductivity limits their rate of heat exchange with a working fluid. The nanofluid approach has been established as a method of thermal conductivity enhancement, but effects of particle addition on other thermal properties affecting TES are relatively ignored. Significant reduction in latent heat of fusion below traditional effective medium theory has been observed in nanofluids. An experimental study of paraffin nanofluids, containing various diameter multi-walled carbon nanotubes, …

Boiling Heat Transfer On Superhydrophobic Surfaces, Nathan Tulett, Dr. Daniel Maynes

Journal of Undergraduate Research

In the last few years a great deal of attention has been given to superhydrophobic surfaces and their impact on drag reduction in fluid flow dynamics. Such surfaces are now employed as self-cleaning substrates and it is expected that their use in the coming years will greatly multiply. In the laboratory, these surfaces often consist of alternating microribs and microcavities that are etched into a silicone substrate using a deep reactive ion etching process (DRIE) as seen in Fig. 1.

Apparatus And Method For Growing Biological Organisms For Fuel And Other Purposes, David J. Bayless, Morgan Lefay Vis-Chiasson, Ben J. Stuart, Gregory G. Kremer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A bioreactor apparatus in which a container has sidewalls, a floor and a ceiling defining a chamber that contains a slurry of water, nutrients and photosynthetic microorganisms. A plurality of optical fibers, each of which has a first end disposed outside the chamber and a second end in the mixture. A light collector spaced from the container has light incident on it and focuses the light onto the first ends of the plurality of optical fibers, thereby permitting the light to be conveyed into the mixture to promote photosynthesis. At least one nozzle is in fluid communication with a source …

Optimizing Redundant Wrist And Forearm Rotations, Jenny Pate, Dr. Steven Charles

Journal of Undergraduate Research

Many Americans struggle with wrist injuries that severely impact their ability to work (typing, writing, etc.) and perform basic everyday functions (eating, holding, etc). These injuries often result from repeatedly forcing the wrist to move in unnatural ways. To properly combat these challenges and improve the lives of wrist patients, a better understanding of the human wrist is required. Extensive research has been conducted in arm reaching movements, but limited documentation has been presented regarding the human wrist. In particular, although it appears that humans choose certain wrist movements over others, it is unclear which paths are preferred, why they …

Using Ebsd Images To Determine 3d Crystal Structure, Caroline Sorensen, Dr. David Fullwood

Journal of Undergraduate Research

The research I have completed over the past year has been very successful. The results will soon (i.e. in the next week or two) be submitted for publication, most likely to the journal “Metallurgical and Material Transactions A.” Preliminary findings from this research were also presented earlier this year at the annual conference of The Minerals, Metals, & Materials Society in San Diego, CA. In this final report I will overview the initial goal and proposed methods, outline a few of the problems that were encountered and solved in my research, discuss the implications of the results, and suggest further …

High Resolution Characterization Of Polycrystalline Triple Junctions, Samikshya Subedi, Dr. David Fullwood

Journal of Undergraduate Research

The purpose of this study was to understand and predict the role of the triple junction on crack initiation in polycrystals. I intended to study dislocation density fields and local elastic strain around the triple junction area in a metal and understand how these factors facilitate crack nucleation and propagation.

Flapping Flight, Michael Tree, Dr. Scott Thomson

Journal of Undergraduate Research

Operation of existing micro air vehicles (small, unmanned aircraft, with a maximum size of 6 inches or less, also known as MAVs) is difficult in urban areas. Most MAVs use a fixed-wing design that is unsuitable for high maneuverability, thus limiting their potential usefulness.

Mathematical Dynamics Of Fluid Motion Inside Of A Spherical Boundary, Taylor Killian, Dr. Tadd Truscott

Journal of Undergraduate Research

The purpose of the proposed research was to mathematically define and model the flow of fluid within a partially filled sphere. The goal of this modeling was to aid the study of the effects an enclosed fluid had on its boundary. We desired to demonstrate the movements of the fluid numerically. Professor Truscott’s laboratory observed that the rebound of a sphere, partially filled with fluid, is greatly reduced by the motion of the fluid inside the sphere and wanted to understand the dynamics of this event.

Capillary Action In A Rectangular Micro-Channel, Jeffrey Hendricks, Dr. Tadd Truscott

Journal of Undergraduate Research

The study of fluid flow on a microscale has become of increasing interest in recent years. We have studied the effects of capillary action in a micro-channel with a rectangular cross-section having a large width to height ratio. In general, capillary action allows fluid to fill a horizontally oriented tube smaller than the capillary length (on the order of 2 mm in water). When the far end of such a tube is capped, typically the fluid is drawn through the tube until it meets a pressure field that is equal but opposite of the surface tension force. We have found …

Rebound Suppression Of A Partially Filled Sphere, Robert Klaus, Dr. Tadd Truscott

Journal of Undergraduate Research

Sloshing is a very common phenomenon that we encounter everyday. Anytime that a liquid is enclosed within a moving container there exists the potential for sloshing. In some cases, such as trucks & ships, the sloshing of the fluid can produce undesired vehicle motion and even lead to catastrophic results. On the other hand, street hockey balls use fluid sloshing to help mitigate the rebound inherent to elastic spheres. In this research, high-speed imaging has been used to capture the sloshing motion and understand its effect on the rebound of partially filled, hollow, elastic spheres.

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering: News & Publications (2013-2023)

• ME Students Win EPA National Competition

• Dr. Soloiu awarded $360,000 National Science Foundation Grant

Lifting-Line Predictions For Induced Drag And Lift In Ground Effect, W. F. Phillips, Doug F. Hunsaker

Mechanical and Aerospace Engineering Faculty Publications

Closed-form relations are presented for estimating ratios of the induced-drag and lift coefficients acting on a wing in ground effect to those acting on the same wing outside the influence of ground effect. The closed-form relations for these ground-effect influence ratios were developed by correlating results obtained from numerical solutions to Prandtl's lifting-line theory. Results show that these influence ratios are not unique functions of the ratio of wing height to wingspan, as is sometimes suggested in the literature. These ground-effect influence ratios also depend on the wing planform, aspect ratio, and lift coefficient.

Momentum Theory With Slipstream Rotation Applied To Wind Turbines, Doug F. Hunsaker, W. F. Phillips

Mechanical and Aerospace Engineering Faculty Publications

A momentum theory which includes the effects of slipstream rotation for wind turbines is presented. The theory accounts for the axial and radial pressure gradients within the slipstream as well as the wake expansion caused by wake rotation. Because of the limiting approximations of previous methods, the effects of slipstream rotation have not been accurately realized. The method included here, which does not suffer from the unrealistic approximations of previous methods, predicts that the effects of slipstream rotation are manifest entirely through an increase in the turbine thrust coefficient. The method predicts, as previous methods do, that the Lanchester-Betz-Joukowski limit …

Decomposed Lifting-Line Predictions And Optimization For Propulsive Efficiency Of Flapping Wings, W. F. Phillips, R. A. Miller, Doug F. Hunsaker

Mechanical and Aerospace Engineering Faculty Publications

A decomposed Fourier series solution to Prandtl's classical lifting-line theory is used to predict the lift, induced-thrust, and power coefficients developed by a flapping wing. A significant advantage of this quasi-steady analytical solution over commonly used numerical methods is the utility provided for optimizing wing flapping cycles. The analytical solution involves five time-dependent functions that could all be optimized to maximize thrust, propulsive efficiency, and/or other performance measures. Results show that by optimizing only two of these five functions, propulsive efficiencies exceeding 97% can be obtained. Results are presented for untwisted rectangular wings in pure plunging, rectangular wings with linear …

Spinning Objects In A Shallow Bath: Eggs In Milk, Kenneth Langley, Dr. Tadd Truscott

Journal of Undergraduate Research

If an egg spinning on a counter-top passes through a shallow pool of milk, a thin film of milk will be drawn up the sides of the egg and sprayed on the counter-top. This phenomenon is not limited to eggs or milk. In fact, when any axis-symmetric object is spun in a shallow bath of fluid, this phenomenon occurs in which fluid flows up the object and is then ejected at the maximum radius. This phenomenon lends itself well as a pump for moving fluids from very shallow areas to other regions and can even be used to make droplets …

Combustion-Driven Water Heating In Huatta, Peru: A Solution For Third-World Countries, Brandon Decker, Dr. Matt Jones

Journal of Undergraduate Research

This group aimed to construct a system that heated water to at least 38°C (100 OF) – warm enough for bathing, dish washing, and washing hands. Our goal was to create a system inexpensive and simple enough for implementation in Huatta, Peru. We also aimed to make the system sustainable and replicable.

Forked Shaped Rebound Droplet For Impingement On Anisotropic Superhydrophobic Surfaces, David Bilodeau, Dr. Daniel Maynes

Journal of Undergraduate Research

Many metals rust when exposed to moisture and that rusting can cause the item that is made of that metal to break down. A superhydrophobic surface can repel liquids and keep metals from rusting longer. Superhydrophobic surfaces have existed in nature for a long time but are just beginning to be understood and manufactured for societal applications. They are manufactured by micro-texturing a surface that is either made from specific materials or is coated with a different material after the micro-texturing (see Figure 1). Both the material and the micro-geometry are important parameters in the surface‟s ability to repel liquids. …

An Improved Estimation Of Passive Wrist Stiffness Using Various Techniques, Will Drake, Dr. Steven Charles

Journal of Undergraduate Research

The wrist plays a vital yet frequently overlooked role in positioning and supporting the hand during activities of daily living. Particularly during low-level activities (such as typing), passive joint stiffness dominates wrist dynamics and constitutes the main obstacle to motion. In spite of its importance, however, little consensus exists as to the exact range of passive wrist stiffness. Reported values vary from as little as 0.002 Nm/rad (Lehman & Calhoun, 1991) to as many as 9.0 Nm/rad (Crisco et al, 2010), a span of three orders of magnitude! The purpose of this research is to determine an approximate single-order-of-magnitude range …

Stand-Alone Lance For Nanoinjection Of Dna, Mark Fernelius, Dr. Larry Howell

Journal of Undergraduate Research

Technologies for injecting DNA into egg cells have greatly facilitated genetic research. Microinjection is a current standard for this purpose. It uses a hollow glass needle to inject a solution containing DNA into cells. Although widely used, microinjection has several significant challenges. First, the DNA can be damaged when forced through the small opening of the needle. Second, the cell can die from the physical trauma caused by the microinjection needle piercing the cell membrane. Third, the cell can split open because of the increased internal pressure caused by injecting fluid into the cell. Brigham Young University has developed nanoinjection …