Engineering Commons^™

Relationship Between Peel Force, Opening Force, And Burst Force For A Semi-Rigid Cup And Lid, Pre- And Post-Retort, Raj Navalakha

All Theses

This research determines if there is any relationship between the peel force, the opening force and the burst force for a semi-rigid cup and lid system, for pre- and post-retort conditions. It also compares the relationship (regression lines) between these forces pre- and post-retort. These seal results were studied by varying the sealing parameters of dwell time and temperature while keeping the pressure constant. Polypropylene cups and a peelable barrier retort lidding were used in this study. As compared to past research, a different peel testing technique was used to measure the peel and the opening force. The entire lid …

Synthesis Of Silicon Carbide Fibers From Polycarbosilane By Electrospinning Method, Yuan Yue

All Theses

Silicon carbide (SiC) is widely used in many fields due to its unique properties. Bulk SiC normally has a flexural strength of 500 - 550 MPa, a Vickers hardness of ~27 GPa, a Young's modulus of 380 - 430 GPa, and a thermal conductivity of approximately 120 W/mK. SiC fibers are of great interest since they are the good candidates for reinforcing ceramic matrix composites (CMCs) because of the weavability and high temperature strength of about two to three GPa at about 1000 °C. Silicon carbide fibers have been synthesized from polycarbosilane (PCS) with ~25 μm diameter using the melt-spinning …

Inverse Problems Using Reduced Basis Method, Phil Gralla

All Theses

Inverse Problems is a field of great interest for many applications, such as parameter identification and image reconstruction. The underlying models of inverse problems in many applications often involve Partial Differential Equations (PDEs). A Reduced Basis (RB) method for solving PDE based inverse problems is introduced in this thesis. The RB has been rigorously established as an efficient approach for solving PDEs in recent years. In this work, we investigate whether the RB method can be used as a regularization for solving ill-posed and nonlinear inverse problems using iterative methods. We rigorously analyze the RB method and prove convergence of …

Thermo-Mechanical Effects Of Thermal Cycled Copper Through Silicon Vias, James Marro

All Theses

The semiconductor industry is currently facing transistor scaling issues due to fabrication thresholds and quantum effects. In this 'More-Than-Moore' era, the industry is developing new ways to increase device performance, such as stacking chips for three-dimensional integrated circuits (3D-IC). The 3D-IC's superior performance over their 2D counterparts can be attributed to the use of vertical interconnects, or through silicon vias (TSV). These interconnects are much shorter, reducing signal delay. However TSVs are susceptible to various thermo-mechanical reliability concerns. Heating during fabrication and use, in conjunction with coefficient of thermal expansion mismatch between the copper TSVs and silicon substrate, create harmful …

Longitudinally Graded Optical Fibers, Alexander Evert

All Theses

Described herein, for the first time to the best of our knowledge, are optical fibers possessing significant compositional gradations along their length due to longitudinal control of the core glass composition. More specifically, MCVD-derived germanosilicate fibers were fabricated that exhibited a gradient of up to about 0.55 weight percent GeO₂ per meter. These gradients are about 1900 times greater than previously reported for fibers possessing longitudinal changes in composition. The refractive index difference is shown to change by about 0.001, representing a numerical aperture change of about 10%, over a fiber length of less than 20 m. The lowest …

Improving R-Value In Brick Systems Using Various Pore-Forming Agents, Graham Shepherd

All Theses

Energy efficiency and energy savings are two topics that have continued to gain momentum over the last decade. This topic is extremely important when it comes to the construction of buildings and homes. Efforts have been ongoing to increase the insulation value of brick systems to hinder the conductive heat transfer through the material. The use of pore-forming agents (PFA’s) have been studied to increase the porosity within a ceramic system, through sacrificial burnout or place–holder method, which leave a residual, defined pore size distribution. This increase in porosity leads to better insulating capabilities and inherently lower conductivity values. In …

Double Paddle Oscillators For The Mechanical Spectroscopy Of Ion-Solid Interactions, Jason Puls

All Theses

We demonstrated using a double paddle oscillator to measure subsurface defect formation at room temperatures caused by ion implantation. This sensor has a low amount of noise based because of its high quality factors in certain modes. The double paddle oscillator was bombarded with Ar ions under ultra-high vacuum conditions while it was oscillating. The resultant resonant frequency changes were discussed as a method to determine defect formation inside the bulk substrate.

Characterization And Restoration Of Historic Rosendale Cement Mortars For The Purpose Of Restoration, Stephanie Hart

All Theses

Mortar was a very common building material in today's historic sites. Before Portland cement was manufactured at a global level, Rosendale cement was commonly used in these mortars. Over time, these mortars in historic sites have begun to break down and wear away. With Rosendale cement in production again, measures can be taken to restore and repair the historic mortars. However, little testing has been done to establish durability of modern Rosendale cement mortars. This presentation highlights the common mix techniques used at the time, and undergoes experiments to establish general properties and predict future durability. Six different mortar mixes …

Preliminary Investigation Into The Design Of Thermally Responsive Forster Resonance Energy Transfer Colloids, Monte Bedford

All Theses

While nuclear imaging techniques (Magnetic Resonance Imaging, Computed Tomography, and Positron Emission Tomography) have proven effective for diagnosis and treatment of disease in the human body, fluorescence-enhanced optical imaging offers additional benefits. Fluorescent imaging provides high resolution with real-time response, persistent lifetime (hours to days), cell targeting, and transdermal penetration with minimal physical encumbrance. Malignant cells can be targeted by absorbance of exogenous fluorescent nanoprobe contrast agents. Imaging is improved by fluorescent enhancement, especially by energy transfer between attached dyes. Also for use against cancer are heat-active treatments, such as hyperthermal, photothermal, and chemothermal therapies. Helpful to these treatments is …

Determination Of A Higher-Order Elastic Constant Of A Single Filament Of Hextow Im7-12k Carbon Fiber Using Finite Deformations, Luciana Oliveira

All Theses

The modulus of elasticity of a homogeneous body is the same for all directions. No known crystalline materials have a Young's modulus that is the same in all directions. The linear theory of elasticity states that strain is proportional to stress so that a straight line is obtained in a stress versus strain plot. As long as the forces applied to the body are proportional, the body behaves perfectly elastically, obeying Hooke's law. At high enough strains, however, deviations from Hooke's law will occur. Nonlinear elasticity is generally apparent when large deformations are applied and usually when the sample size …

Optimization Of Processing Parameters For As2se3 Glass For Low Loss, High Strength Fibers, Baptiste Giroire

All Theses

Chalcogenide glasses have been widely studied due to their extraordinary transparency in the infrared (IR) region from 0.5 to 20 μm. This transparency combined with excellent thermo-mechanical properties, makes them ideal candidate for infrared optics including IR fiber optic applications. However, such non-oxide glasses generally exhibit low mechanical strength, as compared to their oxide counterpart, which are based on covalently bonded metal-oxygen species. In addition to mechanical robustness, low optical loss (hence low impurity content) is required for most IR optical materials, including the one in this study, amorphous arsenic tri-selenide, As2Se3. In this effort, As2Se3 glass was investigated and …

Deformation And Adhesion Of Thin Metallic Films On Flexible Substrates, Julia Reid

All Theses

Flexible electronics are conductive circuits, components and lines integrated onto elastic substrates. These systems often consist of metallic thin films deposited onto thin sheets of glass, metals stainless steel or polymeric materials such as polyethylene or polystyrene. These systems are currently being studied for a wide variety of aeronautic and astronautical applications including: electronic skins, solar sails, and antennae structures. For applications include only moderately elevated temperatures (near 200 ¡C) and low strains (insert range), engineers have proposed incorporation metallic lines onto polymeric substrates. Like traditional microelectronic systems with films on hard substrates, the reliability is controlled by the film-substrate …

Measuring Ligand Exchange On The Surface Of Gold Nanoparticles: A Study Of Competitive Binding Of Ligands Utilizing Fluorescent Resonance Energy Transfer, Daniel D'Unger

All Theses

This study was conducted to track ligand exchange on the surface of metallic nanoparticles in order obtain a better understanding of binding strength of various functional groups. This study develops groundwork for further understanding ligand exchange as nanoparticles transition from engineered to natural systems. A problem exists in knowing the fate of these particles if they are released into natural systems, by accident or with intent. To gain a better understanding of what may occur we look at the binding strength of different ligands. This is done to gain knowledge of the possibility of displacement of ligands occurring in the …

Tribiology Of Engineered Surfaces In Aggressive Environments, Nathan Phillip Mitchell

All Theses

To improve the performance of sliding systems, surface modifications and coatings are often applied to opposing surfaces. This thesis focuses on characterizing two tribo-systems (DLC-DLC and steel micropatterns-flat) under their predicted application environments. The first section is focused on friction testing of micropatterned surfaces for orthopaedic device design, the second section elucidates how the sliding of diamond-like-carbon (DLC) coatings changes with temperature and humidity. The experimental design and major results of these sections are as follows.

(1) The use of micropatterning to create uniform surface morphologies has been cited as yielding improvements in the coefficient of friction during high velocity …

Surface Characterization Of Nephila Clavipes Dragline Silk, Benoit Faugas

All Theses

To design synthetic fibers for extreme applications, many research groups are trying to identify how the structure of natural fibers (such as spider silk) leads to desirable properties such as high tensile strength.
Spider silk is a biological fiber having mechanical properties that exceed those of the best man made fibers in terms of high tensile strength and large extensibility, this combination providing the silk with a large work of rupture. While the bulk structure, composition and properties have been intensively studied elsewhere, this study focuses on elucidating the Nephila clavipes spider dragline silk surface structure and composition, as well …

Nanoparticles In Solution-Derived Chalcogenide Glass Films, Spencer Novak

All Theses

The results in this thesis are from our efforts to modify the optical properties of solution-derived chalcogenide glass films by the incorporation of nanomaterials. First, the composition Ge23Sb7S70 was selected as the appropriate glass matrix for testing because solution-derived films of this composition have been well-studied in our group. Additionally, this composition was found to be less sensitive to certain processing parameters than As2S3, another well-studied, candidate chalcogenide glass composition, making Ge23Sb7S70 more suitable for the addition of nanomaterials. Optimization of film process parameters was performed to obtain high-quality films appropriate for doping with nanomaterials. This consisted of determining the …

Characterization And Optimization Of Solution-Derived Chalcogenide Glass Thin Films, Jacklyn Wilkinson

All Theses

Chalcogenide glasses have many unique properties that allow them to be used in a variety of optical applications. Infrared transparency allows them to be used in sensors for molecules that have 'fingerprints' in the 2-25 μm range. By producing amorphous thin films of these materials, they can be incorporated into chemical sensors as planar waveguides and resonators. The goal of this work was to fabricate and characterize solution-derived chalcogenide thin films for use in chemical sensors with a source wavelength between 3-3.5 μm.
The structural and optical properties of the parent bulk glass were characterized and used as reference for …

Printing Carbon Nanotube Based Supercapacitors For Packaging, Alexandra Hartman

All Theses

Living in a world full of portable electronics, there is great need for energy storage devices. Currently, limitations for storage involve power inefficiencies as well as bulkiness. This is why printable charge storage devices that display good electrochemical performance are needed. It is for this reason that research into the production and packaging of carbon nanotube based super capacitors was carried out.
A super capacitor can be built by using high surface area multi-walled carbon nanotubes suspended in an ionic liquid. The two active electrodes are made from a combination of the multi-walled carbon nanotubes and an ionic liquid, ground …

Empirical Study: Failure Of Glass-To-Metal Seals During Shock Loading, William Horton

All Theses

The goal of this thesis was to determine the empirical failure mechanisms and sequence of cartridge actuated devices (CADs) experiencing failure of the glass-to-metal (G/M) seal. Impact loading was conducted with a drop weight machine at room temperature and 300¡F, and then empirically analyzed with high speed video. Resulting peak overload force, shear stress, and impulse were all calculated. The room temperature samples were found to absorb twice the impulse upon failure as the elevated temperature G/M seals. Closed-form and three-dimensional finite element analysis was used to determine the stress state and deformation upon loading. Furthermore, high speed data was …

Effect Of Selected Phase Change Materials Concentration And Manufacturing Process On The Properties Of Plaster Mixture Systems, Rong Cui

All Theses

Phase change materials (PCM) are generally used in building construction materials for their ability to absorb and release large amounts of energy when their phase change happens at their specific melting temperature. This results in a significant increase in thermal mass of the building, a reduction in temperature fluctuations and therefore a reduction in heating and cooling loads. However, in order to properly select a PCM and optimize its integration in a specific building, the properties of building construction materials enhanced with PCM must be known. This research focuses on studying the effects of the concentration of a micro-encapsulated PCM …

Novel Oxadiazole Containing Monomers For Polymeric Light Emitting Devices, Alexandra Foguth

All Theses

Organic light emitting diodes (OLED) have received a great deal of
attention in the research community in the past few decades. This
work focuses on OLEDs utilizing the donor-acceptor operational
approach. In specific a single layer device architecture with an
emissive layer of copolymerized hole and electron transport moieties
in an effort to frustrate phase segregation that can occur during
device operation. A new methacryalate based oxadiazole monomer,
4-[5-(biphenly-4-yl)- 1,3,4-oxadiazol-2-yl] phenyl methacrylate (mPBD) an electron transporter, was successfully synthesized. The new monomer was copolymerized with N-vinylcarbazole (VK), a hole transporter, to form statistical copolymers. The glass transition of the copolymers …

Role Of Surface Coatings In Lithium-Ion Batteries, Archana Kayyar

All Theses

Rechargeable batteries that can charge and discharge at high rates have applications in hybrid and plug-in hybrid vehicles and they provide energy storages for wind energy. Various methods like reducing particle size, aliovalent doping and carbon coating have been researched in order to attain higher charge and discharge rates in rechargeable Li-ion batteries. In this work, the electrode materials were coated with amorphous films in an attempt to improve the rate capability of the batteries.
A study by Kang and Ceder suggested that a Li₄P₂O₇-like 'fast-ion conducting surface phase' could form on the surface …

Influence Of Aging And Severe Plastic Deformation On The Shape Memory Behavior Of Ti-50.6at%Ni, William Shirley

All Theses

Martensitic phase transformations were investigated for Ti -50.6 at % Ni processed via severe plastic deformation (SPD) and subsequent aging for temperatures between 400 and 550C and times ranging from 1hr to 100hrs. Phase transformations of the SPD material were compared to material processed via solution treated at 800C and 850C for 1hr. Transformations were investigated with differential scanning calorimetry (DSC) and confirmed by X-ray diffraction (XRD) with optical microscopy being used to determine grain size. Solution treated samples displayed a single (1-1) B2↔B19' transformation prior to and upon initial aging, i.e. 400C/1h, 450C/1/10h. Intermediate aging conditions, 450C/100h; 500C/1/10/100h; and …

The Development Of A Far Red To Near Infrared Fluorescent Probe For Use In Optical Imaging, Margaret Fiedler

All Theses

New techniques for biological optical imaging are of great interest for the detection and visualization of processes and disease in both clinical and research areas. One major advancement has been the use of far red and near infrared (NIR) light, as it has the ability to penetrate tissues deeper than other parts of the spectrum which are readily scatter and absorbed by the surroundings. In order to improve the signal to noise ratio and resolution of optical images, contrast agents are used. Fluorescent markers can be modified to attach to specific molecular targets, creating small molecular probes. These targets can …

Effect Of Accelerated Aging On Mechanical Properties And Structure Of Nano-Scale Composite Systems, David Economy

All Theses

Nano-scale composites are being investigated by academic, industrial, and national laboratories for potential applications such as wear resistant coatings and high strength foils. These structures are of interest due to their as-fabricated mechanical properties, such as high strength for nanolaminates. However, there have only been limited studies of the long-term mechanical stability. A greater understanding of how these systems might respond to sustained use is needed before these systems transition from research laboratories into widespread application. It is the objective of this thesis to clarify the link between accelerated aging using elevated temperatures over time and mechanical properties of two …

Stress Relaxation Of Glass Using A Parallel Plate Viscometer, Guy-Marie Vallet

All Theses

Currently, grinding and polishing is the traditional method for manufacturing optical glass lenses. However, for a few years now, precision glass molding has gained importance for its flexibility in manufacturing aspheric lenses. With this new method, glass viscoelasticity and more specifically stress relaxation are important phenomena in the glass transition region to control the molding process and to predict the final lens shape.
The goal of this research is to extract stress relaxation parameters in shear of Pyrex¨ glass by using a Parallel Plate Viscometer (PPV). The PPV machine was originally created to measure the viscosity of glass solid cylinders …

Substrate Topography Design And Fabrication For Osteoblast And Dental Pulp Stem Cells Studies, Gloria Chen

All Theses

Research for cell guidance based tissue engineering has rapidly grown due to the increasing interest in tissue engineering and reconstructive medicine applications, such as cranial reconstruction. Many research teams have begun the process of identifying what factors influence cell behavior (including cell growth, proliferation, alignment and spreading). Published studies have pointed to the influence of the cell medial pH, substrate stiffness, chemistry and topography. Conclusive results are often hard to identify since researchers often vary many of these factors simultaneously and it is hard to decouple individual factor influence. These reports also points out that the cellular response can be …

Influence Of Material Selection And Fabrication Process Repeatability On Mechanical Properties Of Glass-Polymer Matrix Composite Structures, Charles Edwards

All Theses

This study has aimed to evaluate property uniformity from data obtained utilizing one design of a single layup composite plaque, three sources of glass fibers and a single, industry accepted resin to produce a repeatable fabrication process. This thesis has investigated the following:
1. Whether the type of glass (E-Glass, S-Glass, and R-Glass) influences the property values of individually tested samples compared between glass types.
2. Whether the type of glass influences the property uniformity throughout the set of tested samples.
3. Whether the composite plaque design and resulting performance, as defined by ASTM Standards or industry accepted parameters, is …

Integrating Phase Change Materials In Building Materials: Experimentation, Characterization And Numerical Simulation, Esvar Subramanian

All Theses

Phase Change Materials (PCM) have many commercial applications, including in buildings to reduce cooling and heating loads. However, the lack of research has prevented their use as a common building material. This research is part of a larger project that aims at developing a set of practical design guidelines for integrating PCM in buildings. A review of and classification of common PCM available on the market is provided. The thesis then focuses on the experimental characterization of the thermo-physical properties of PCM-integrated building materials and the development of a numerical model for the thermal analysis of buildings with PCM. Different …

Optimizing The Mechanical Properties Of Partially Yttria Stabilized Zirconia With Alumina Additions, Ramanaganapathy Kandaswamy

All Theses

Zirconia is one of the extensively studied solid oxide ceramics with respect to its use in various industrial applications like electrolyte in fuel cells, sensors, refractories and exhaust chamber in automobile industry. It can be found from the literature 1-4 that are contradictory results on the mechanical properties when alumina is added. There are several factors like microstructure, phase composition and method of processing that affects the mechanical properties of the material. The focus of this research is to examine how hardness, tensile strength and other properties varies with alumina content and deduce the optimal amount of alumina that is …