Mechanical Engineering Commons^™

Influences Of Material Extrusion Additive Manufacturing (Meam) Parameters And Additives On Polyvinylidene Fluoride (Pvdf) Properties., Niknam Momenzadeh

Electronic Theses and Dissertations

Beyond the beneficial characteristics of smart polymers associated with all polymers such as flexibility and cost fabrication, smart materials exhibit multifunctional behaviors. The prospect of integrating structural and sensing/actuation capabilities into a single structure gives design engineers an ability to innovate highly novel, multi-functional creations. Polyvinylidene Fluoride (PVDF) is one of the widely used multi-functional materials which offers a variety of desirable material properties. It possesses exceptional chemical and UV resistance, biocompatibility, low processing temperature and affordable price making it a competitive choice for many commercial applications. In addition, among polymers, PVDF is simply the most dominant piezoelectric polymer. On …

A History And Status Of Wind Energy Potential In Arkansas, Pre And Post Covid-19, Will Blasingame

Mechanical Engineering Undergraduate Honors Theses

Historically, wind-generated electricity has been the largest renewable energy sources in the United States. Wind-rich regions like Oklahoma and Texas have fueled growth and sold that electricity to electric utilities located in wind-poor states like Arkansas in the form of Power Purchase Agreements. Future technologies such as Vertical Axis Wind Turbines, small wind turbines, and Tesla turbines designed to generate electricity from wind show promise in unlocking more expensive wind resources in regions like Northwest Arkansas by mitigating concerns about low wind speeds and noise. However, more factors than just feasibility influence the growth of wind power. Governmental policies such …

Construction Of A Hyperspectral Imager Using 3d-Printed And Off-The-Shelf Components, Joshua Moorhouse

Mechanical Engineering Undergraduate Honors Theses

The Arkansas Center for Space and Planetary Sciences is working in collaboration with the Mechanical Engineering department to create a relatively cheap and modifiable hyperspectral imager. It is constructed using 3D-printed and off-the-shelf components from Edmund Optics and Amazon. The iteration created in this paper delivers spectrograms in the visible spectrum. The long-term goals of the camera are to create hyperspectral images from these spectrograms and to advance the imager into the infrared and near-infrared spectra. This imager is being developed to be used in the Arkansas Center for Space and Planetary Sciences environmental test chambers to further the scientific …

Enhancement Of Phase Change Material Sorbitol By Nanoparticle Inclusion For Improving Thermal Energy Storage Capabilities, Joshua Kasitz

Mechanical Engineering Undergraduate Honors Theses

Thermal management of electronic devices has become an increasingly vital field of study with the rapid miniaturization of many key electrical components. With the significant improvement of semiconductor manufacturing and intensified focus on interconnects, electronic devices have decreased in size at an incredible rate. Decreasing spatial requirements is essential to improving device capabilities as the electronic system is able to incorporate more components. Currently, electronic systems are drastically limited by the capabilities of their cooling mechanisms. Smaller devices lead to large increases in the energy density of the system and require more powerful cooling systems to maintain proper component operating …

Design Of An Environmentally Responsive Grooming Tool To Aid In Underwater Navigation, Bruce Huntress Walker Iii

Theses and Dissertations

Underwater hull grooming is a proactive approach to ship hull husbandry. It has been defined as the frequent and gentle wiping of a ship hull coating to maintain it free of fouling. One of the challenges to implementing a grooming schedule is the control and navigation of the devices over the surface of the hull. This thesis presents prior research that has developed self-attaching rotating brushes as an effective method to groom fouling control coatings and the results from several years of implementation in the marine environment. The hypothesis of this thesis is that the condition of the ship hull …

Spherical Cavity Expansion Approach For The Study Of Rigid-Penetrator’S Impact Problems, Mario Buchely, Alejandro Marañon

Materials Science and Engineering Faculty Research & Creative Works

In recent years, Spherical Cavity Expansion (SCE) theory has been extensively utilized to model dynamic deformation processes related to indentation and penetration problems in many fields. In this review, the SCE theory is introduced by explaining the different mathematical features of this theory, its solution, and a potential application to model the penetration of a rigid penetrator into a deformable target. First, a chronologically literature review of the most common models used to study this kind of penetration problems is introduced, focusing on the SCE theory. Then, the engineering model of penetration is presented using the SCE approach. The model …

Analog Versus Digital Guitar Pedals, Shaping Guitar Tones And Sparking Debates, Cameron Karren

Capstone Projects and Master's Theses

This paper goes into the history of guitar effects, what exactly they are, how they have evolved, and what they are like today. It also presents the results of an experiment that compares perceptions of differences between analog and digital guitar pedals.

Computational Analysis Of A New Planar Mixing Layer Flame Configuration To Study Soot Inception, Carmen Ciardiello

Honors Scholar Theses

The production of soot is omnipresent in society today. Soot is the product of many of the combustion processes that provide the bulk of the usable energy throughout the world. Furthermore, soot particulate poses a great danger to both the environment and all forms of life on Earth. It has proven to pollute ecosystems, foster health problems for human beings, and degrade air quality [1].

These dangers make studying and understanding soot particulate paramount for improving the quality of life. Thus, this study introduces a new flame configuration for studying soot inception. Presently, various common flame configurations have been found …

Thermodynamic Potential Of Very High Performance Fuel Cells, Kimberly Liang

Honors Scholar Theses

Fuel Cells are devices that use the chemical energy of a fuel (e.g. hydrogen) to electrochemically produce electricity. Similar to a conventual combustion engine, a fuel cell will continue to run and generate electricity as long as fuel is supplied. However, unlike a conventional combustion engine, fuel cells have a much higher theoretical efficiency and do not directly emit harmful air pollutants. This project will focus on a fuel cell that uses hydrogen as fuel and oxygen as an oxidizing agent.

As fuel cell technology evolved, high pressure fuel cell systems became of interest in portable applications, such as submarine …

An Assessment Of Renewable Energy Technology Implementation In Storrs, Connecticut: Emissions Reduction And Feasibility Of A Microgrid System At Uconn, Sophie Macdonald

Honors Scholar Theses

The purpose of this project is to design a clean energy-sourced microgrid for UConn’s main campus that would reduce the university’s energy emissions while remaining within the geographic boundaries of viable UConn-owned land. Economic cost was not considered in this analysis; instead, emissions and space constraints were the optimized measures of value and feasibility. Sources of energy that were considered include photovoltaics (PV), wind turbines, hydrokinetic systems, and fuel cells. Energy storage capacity was included in the analysis as well. The overall system was optimized first by ignoring space constraints and for a minimum of 10% reduction from the current …

Design, Analysis, And Demonstration Of A Multipurpose Fluid Tank Dynamics Characterization Platform, Cameron Ian Hume

Theses and Dissertations

The development of a highly versatile multiphase fluid tank characterization platform is essential to the analysis and improvement of propellant storage tanks. The performance of these tanks is highly critical to the safety and performance of their carriers, especially in the space industry where the propellant makes up the overwhelming majority of the mass of the vehicle. This thesis outlines the design and development of a linear stage used to test and validate the characteristic of multiphase fluids inside moving specific tanks. This document will walk through the steps taken to bring a new linear stage to life, from the …

Development Of Vegetable Oil Based Nano-Lubricants, Vicente Cortes

Theses and Dissertations

Nowadays, the depletion of crude oil reserves in the world and the global concern in protecting the environment from contamination have renewed interest in developing environment friendly lubricants derived from alternative sources such as vegetable oils. Mineral oil is the most common lubricant, however, it also has poor biodegradable properties. Vegetable oils exhibit good viscosity index, flash point, pour point, tribological properties, and are biodegradable. Furthermore, the use of nanoparticles as additives has shown to improve anti wear and anti-friction properties of the base lubricant. The present research project will evaluate experimentally the rheological and tribological behavior of coconut oil, …

Processing And Microstructural Characterization Of Silicon Carbide, Silicon Nitride, And Tungsten Carbide Fibers, Christian Garcia

Theses and Dissertations

This research focuses on developing polymer-derived ceramic fibers. The spun micro/nanofibers were sintered into silicon carbide/silicon nitride and tungsten carbide respectively. The relationship between processing, fiber microstructure, morphology, and purity is investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. Dynamic Mechanical Analysis was used to test the reinforcement capabilities of tungsten carbide fibers. EDS identified a near-perfect 1:1 Si-C ratio in silicon carbide fibers sintered between 1200 °C -1400 °C, Silicon carbide was confirmed by FTIR between 1000 °C – 1400 °C. Silicon Nitride peaks were noted in FTIR between 1200 °C – …

Residual Service Life Prognostic Models For Tapered Roller Bearings, Jennifer Danni Lima

Theses and Dissertations

There are a few different bearing health monitoring technologies currently used in the railroad industry, both reactive and preventative detection systems. Reactive models have proven to be ineffective in monitoring bearing health, which has resulted in either unnecessary train stoppages and delays or in-service failures and bearing burn-off leading to catastrophic train derailments. Wayside preventative detection systems, while more effective than reactive technologies, are scarce and neglect railcars’ that do not travel over a specific route. This knowledge prompted the University Transportation Center for Railway Safety at UTRGV to develop an onboard bearing health monitoring system that can accurately assess …

Bio-Inspired Wings In High Freestream Turbulence: A Numerical And Experimental Study, Alexia Martinez Ibarra

Theses and Dissertations

The aerodynamics and flow field characteristics of a NACA 0010 airfoil with leading-edge modifications were investigated in flow with freestream turbulence intensity of 4%. A set of 4 airfoils, each of them with different wavelength (4, 8, 10, 12 tubercles along the spanwise direction) was experimentally studied. An unmodified NACA 0010 airfoil was used as baseline. The Reynolds number was varied from 201,200 to 351,600. The angle of attack was varied within the range of -6 to 20 degrees. Several techniques were used to investigate the characteristics of the airfoils such as wake profile surveys, 6-axis force measurements, and Particle …

3-D Silk Fibroin Porous Particles Created By The Ouzo Effect For Biomedical Applications, Ashley Nicole Lamb

UNLV Theses, Dissertations, Professional Papers, and Capstones

Due to its high biocompatibility and biodegradability, silk fibroin – produced from

Bombyx mori (B. mori) cocoons – has been at the forefront of research for many

biomedical application formats: hydrogels, films, microspheres, and porous

sponges/scaffolding, to name a few. For drug delivery, in particular, porous particles are

desirable for their large surface area, uniform and tunable pore structure, and high

porosity. This thesis focuses on the fabrication of porous particles from silk fibroin by the

very interesting Ouzo effect. The Ouzo effect, so named because of the Greek

beverage ouzo, describes the phenomenon of an ethanol + anethole oil …

Impact Of Magnetocaloric Material Properties On Performance Of A Magnetocaloric Heat Pump., Michael G. Schroeder

Electronic Theses and Dissertations

In the field of magnetocaloric heat pumps much research has been performed around machine design and theoretical machines, but little has been researched around practical problems such as variability in material properties. The present work defines a simulation tool that has been proven with experimental data. Magnetocaloric material cascades were statistically analyzed and parameterized, such that they could be recreated parametrically using a split Lorentz function with normally distributed parameters. Correlated curve-defining values with standard deviations were used as input into the simulation tool to determine the effect of variation on cooling heat pump performance for a household refrigerator application. …

A Study On Reaction Rate Factors Of A Single-Step Combustion Mechanism For Gasoline Hcci Combustion, Pakawat Panuwatsuk

Theses and Dissertations

Homogeneous Charge Compression Ignition (HCCI) engine has been invented to achieve the advantages of both diesel and gasoline engines. HCCI engine can run with a higher compression ratio like diesel engine in order to achieve high thermal efficiency. Meanwhile, like gasoline engine, the engine produces less NOx gas and particulate matters than diesel engine. However, there are several difficulties associated with HCCI combustion, which still require further development to the engine. The most important issues are autoignition timing and narrow operational range. In order to develop an HCCI engine, a numerical simulation can significantly save cost, time and resources over …

The Development And Evaluation Of A New Analytical Model For The Characterization Of Friction Induced Disc Brake Vibration, Michael Vladimirov

Master's Theses

This research proposes a new method of modeling vibration of disc brake systems. This modeling method treats the brake pads of a disc braking system as lumped spring-mass-damper subsystems and the disc as a continuous bar. This modeling concept increases both the ease of analytical expression and the insight provided into the behavior of the real-world systems. This paper describes the analytical expression of this model and its implementation in Matlab. A parameter variation study yielded results that agree with existing research, which serves to validate the fundamental principles of this proposed modeling method.

Service Dog Ramp, Matthew Lundgren, Ariel Tolentino, Dallas Rocha, Adam Mayeda

Mechanical Engineering

This project involves designing a device to help a service dog easily get into and out of a truck. It details the design and manufacturing process. The project was interrupted due to the COVID-19 pandemic, so detailed instructions are provided for whoever takes on the project in the future.

Towards A High Bias Voltage Mems Filter Using Electrostatic Levitation, Mark Pallay, Ronald Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

Traditional MEMS filters use a comb drive structure that suffers from the pull- in instability, which places a significant limitation on the achievable signal-to- noise ration of the sensor. Because the output signal from a capacitive sensor

is linearly related to the applied voltage, it is desirable to use a capacitive sensor that can withstand large voltages upwards of 100V. However, the pull-in instability causes high voltages to destroy the device and a trade-off between performance and reliability must be made. Electrostatic levitation, which works by pulling electrodes apart instead of together, eliminates the pull-in instability and allows for very …

Delineating The Relationship Between Cardiovascular Physiology And Subject Characteristics Using Computational Modeling And Systemic Review, Aseem Pradhan

All Theses

Lumped Parameter Networks (LPN) are computational models that can capture the systemic responses of the cardiovascular system. An LPN describes the systemic behavior by providing outputs such as the blood pressure, flowrate, and heart chamber volume at the points defined in the network. To use the LPN for medical applications, it needs to provide output values that represent the physiology of realistic subjects. The cardiovascular system exhibits short-term and long-term adaptations to factors such as aging, weight gain, exercise, etc. Therefore, subject characteristics such as age, height, weight, etc. affect the output values of the LPN. Current literature reports the …

Thermal Management Design Of A 6u Cubesat With A High-Power Additive Manufacturing Payload Using Analytical Modeling With Experimental Validation, Todd Wayne Fennell Jr.

Theses and Dissertations

As the capacity of compact battery technology for spacecraft missions continue to improve, small payloads are less constrained by power limitations, thus relatively high-power applications may be considered. AddCube is a mission to develop a platform, conforming to the 6U CubeSat Standard capable of demonstrating on-orbit Additive Manufacturing technology. A critical concern is the development and demonstration of a thermal management design that is capable of handling the significant waste heat generated by the high-power Additive Manufacturing payload while maintaining component temperatures throughout the spacecraft within an acceptable range. This effort includes a trade study for the evaluation of candidate …

Effects Of Polytetrafluoroethylenemicro–Particles On Mechanical Andtribological Properties Of Glass Fiberreinforced Polyoxymethylene, Kunnan Singh Jasbir Singh

Student Works (2020-2029)

Reinforcing polyoxymethylene (POM) with glass fibers (GF) enhances its mechanical properties, but at the expense of tribological performance. Formation of a transfer film to facilitate tribo–contact is compromised due to the abrasiveness of GF. As a solid lubricant, for example, polytetrafluoroethylene (PTFE) significantly improves friction and wear resistance. The effects of chemically etched PTFE micro–particles on the fiber– matrix interface of POM/GF/PTFE composites have not been systematically characterized. This research investigated the effects of PTFE micro–particles on mechanical and tribological properties of POM/GF/PTFE composites. Since PTFE is immiscible with most polymers, the surface was etched using sodium naphthalene salt dissolved …

Mechanical Properties And Microstructure Evolution Of Ti2alc Under Compression In 25–1100 °C Temperature Range, Rogelio Benitez, W. H. Kan, H. Gao, M. O'Neal, G. Proust, A. Srivastava, Miladin Radovic

Mechanical Engineering Faculty Publications

This study investigates the effects of the initial grain size and temperature (ranging from room temperature to 1100 °C) on the mechanical properties and microstructure evolution of Ti2AlC MAX phase. A Hall-Petch like relationship is observed between compressive strength and the grain size below brittle-to-plastic transition temperature (BPTT). However, the compressive strength of fine-grained MAX phase decreases more rapidly with increasing temperature resulting in inverse Hall-Petch effect above BPTT. Results from postmortem EBSD analysis reveal complex microstructural evolution in both fine- and coarse-grained microstructures during loading at different temperatures. The pronounced drop in compressive strength for fine-grained microstructures at temperatures …

A Model For Simulation Of Convective Heat Assisted Single Point Incremental Forming Of Thermoplastics, Shubhamkar Kulkarni

All Dissertations

The overarching objective of this research is to develop a finite element model for simulation of the single point incremental forming (SPIF) process at different temperatures including convective heat assisted SPIF (CHASPIF). Single point incremental forming (SPIF) is a flexible manufacturing process with low tooling costs and times compared to thermoforming and die forming, for low production volumes. Convective heat assisted single point incremental forming (CHASPIF) is a variant of the SPIF process in which an external hot air source is used to heat the region surrounding the tool to improve formability, which can be assessed either in terms of …

Analysis Of Polyester Interleafs For Toughness Enhancement In Composite Structures, Adnan Gheryani

Theses and Dissertations

Delamination between composite layers is one of primary weaknesses in composite material structure. Various researchers have developed techniques to control delamination in laminated structures. One of these techniques is “interleaving,” adding high toughness material to key interfaces in a laminate. This research studies using polyester veil as a low-cost interleaf alternative to other materials and focuses on a non-woven, polyester spunbond material. Two different interleaf thicknesses, 0.18 mm and 0.74 mm are primarily used. In addition, fine 4 g/m2 polyester was also compared. Carbon/epoxy composites are manufactured using 2x2 Twill 24”-12k carbon fibers embedded in an epoxy resin, with polyester …

Living Docks: Structural Implications And Determination Of Force Coefficients Of Oyster Mats On Dock Pilings In The Indian River Lagoon, Ryan Christiansen

Theses and Dissertations

Brevard County, Florida, is facing rapid population growth and increased pollution entering the Indian River Lagoon (IRL), impairing water quality and damaging the ecosystem. This is problematic not only for public health and environmental stability, but also for the economy. The Living Docks initiative was created to combat environmental degrade in the lagoon and restore natural functions back to the ecosystem. With increased urbanization along coastal systems, there is opportunity for new forms of ecological engineering such as Living Docks, which attaches oyster mats to dock pilings as a means to promote the growth of filter feeding organisms. It is …

3d Parametric Hand To Improve Prosthetic Hand Functionality, Maria C. Gerardi

UNLV Theses, Dissertations, Professional Papers, and Capstones

The use of prosthetics can significantly enhance an individual’s standard of living, not only offering functional advantages but psychological advantages as well. Unfortunately for children with upper limb reduction, options are limited and rejection rates are high due to a multitude of reasons including discomfort and poor functionality. This study proposes a new parametric 3D design model (Parametric Hand) with an adjustable thumb that can be easily manipulated to the uniqueness of an individual. The Parametric Hand was evaluated, both qualitatively and quantitatively, against the Flexy-Hand 2, a commonly used prosthetic hand. The results showed insignificant differences in all testing …

Material Characterization Of Fiber-Reinforced Composite Materials Under Dynamic Loading Condition, Abu Iqbal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fiber reinforced composites are light materials which exhibits great strength and stiffness. They also have good dimensional stability and impact resistance. They reduce mass and improve structural performance, so the demand for fiber reinforced composite materials increases day by day in various industries such as aeronautical, automobile and military. The analysis, design, and optimization of polymer composite materials under static loading conditions are mature fields of study. Many sources are available to find material properties and predict structural response. However, composite materials are often used in extreme environments where they are subject to shock, impact, and blast loading. Efficient computational …