Materials Science and Engineering Commons^™

An Investigation Of Initially Delaminated Composite Sandwich With Delamination Arrest Mechanism Under Buckling Loading, Tony D. Tran

Master's Theses

This thesis involves the development of a fiberglass-foam composite sandwich structure with the introduction of delamination arrestment keys; therefore, a study of an initially delaminated composite sandwich structure was the experimental analysis on multiple configurations in how the arrestment keys are placed.

The first part of this thesis research was to the experimental design and manufacturing of the composite sandwich plates. These plates were later cut down to the specific test dimensions and manufacturing processes for the composite sandwich plates and test specimens were created. The composite sandwich plates were manufactured using a vacuum resin infusion process. The dimensions of …

Characterization Of Inconel 718: Using The Gleeble And Varestraint Testing Methods To Determine The Weldability Of Inconel 718, Nathaniel Oscar Knock

Master's Theses

Nickel based superalloys were developed to withstand the severe thermal and mechanical environment associated with rocket propulsion systems and jet engines. In many alloy systems the strength of a component rapidly deteriorates as the operating temperature increases. Nickel based superalloys, however, retain strength over a range of temperatures which includes the operating range for many propulsion systems. This improved performance is accomplished by a combination of solid-solution strengthening, precipitation strengthening and grain-boundary strengthening. Furthermore, super-alloy systems are designed for ease of fabrication, to include machining, welding and heat treating. Inconel 718 was developed to overcome problems with post-weld cracking that …

Nanoindentation Of Annealed And As-Sputtered Thin Films Of Nickel Titanium Shape Memory Alloys, Matthew Tyson Lewis

Master's Theses

The bottom-up processing techniques used for making Microelectromechanical systems (MEMS) devices can produce material properties different from bulk processing. The material properties must be evaluated with the process parameters used and for changes in the process parameters. The mechanical properties are needed to design MEMS devices. A material of interest for MEMS devices is nickel titanium (NiTi) shape memory alloy (SMA) because of the high work output (~107 J/m3). This thesis will focus on the fabrication of thin film NiTi by DC magnetron sputtering deposition and testing mechanical properties of the fabricated films by nanoindentation. Thin film NiTi SMA was …

Corrosion Dynamics Of Cobalt-Chromium Alloy F-75 Powder, Tedman Tong

Master's Theses

The increasing usage of metal-on-metal joint replacements consisting of a cobalt-chromium-molybdenum alloy requires increasing concern regarding the inevitable generation of metallic wear debris. Patients with these joint replacements exhibit elevated concentrations of cobalt and chromium ions within their serum, blood and urine. The presence of these metal ions suggests the potential for bodily damage and indicates corrosive processes are acting upon wear debris.

To understand the behavior of these corrosive processes, powders of cobalt-chromium-molybdenum alloy F-75 were studied. Four powder sizes (44, 74, 105, and 420 µm diameter) were subjected to Hank’s Balanced Salt Solution (HBSS) for a 42 day …

The Effects Of Applied Strain And Heat Treatment On The Properties Of Niti Wire During Shape Setting, Frank Zapoticla

Master's Theses

NiTi components are commonly subjected to thermo-mechanical heat treatments during production and fabrication. This study investigates the effects of applied strain of 0-10% and heat treatments of 300-600ºC for times of 2-30 minutes during shape-setting of Ti–50.8 at% Ni wire with a nominal diameter of 0.495 mm and an initial transition temperature, Af, of 12ºC. Strain was applied prior to heat treatments by coiling NiTi wire, essentially producing coiled springs, around different diameter steel mandrels to obtain different strain levels. The samples of NiTi wire under applied strain were heat treated in a salt bath, followed by a rapid quench. …

Tribological Comparison Of Traditional And Advanced Firearm Coatings, Greg Boban

Master's Theses

The objective of this project is to find which type of coating has the best performance characteristics for finishing firearms. This is accomplished by measuring and comparing several performance characteristics, such as: adhesion, hardness, wear resistance, friction control, and corrosion resistance. Appearance is not a factor since any exterior coating that is flashy can be subdued or camouflaged with special purpose paints, which have proven durable enough for such purposes. Cost will not be a limiting factor for this experiment, but will be discussed in the conclusion as a secondary concern. This data will be used to identify the best …

Feasibility Of Manipulating Correlated Color Temperatures With A Phosphor Converted High-Powered Light Emitting Diode White Light Source, Matthew Michael Little

Master's Theses

In this thesis we examine the feasibility of developing a white light source capable of producing colors between 2500 and 7500 Kelvin on the black-body radiator spectrum by simply adjusting amperage to a blue and ultraviolet (UV) light emitting diode (LED). The purpose of a lighting source of this nature is to better replicate daylight inside a building at a given time of day. This study analyzes the proposed light source using a 385 nm UV LED, a 457 nm blue LED, a 479 nm blue LED, a 562 nm peak cerium doped yttrium aluminum garnet (YAG:Ce) phosphor, and a …

The Characterization And Analysis Of In-Vitro And Elevated Temperature Repassivation Of Ti-6al-4v Via Afm Techniques, Aaron J. Guerrero

Master's Theses

ABSTRACT

The Characterization and Analysis of In-vitro and Elevated Temperature Repassivation of

Ti-6Al-4V via AFM Techniques

Aaron J Guerrero

Research in the corrosion of orthopaedic implants is a growing research field where implants have been known to show adverse effects in patients who have encountered the unfortunate dissolution of their implants due to corrosion. Once corrosion begins within the body, many adverse biological reactions can occur such as late on-set infections resulting in severe health complications. The focus of this research is specifically related to the problem of late on-set infections caused by localized corrosion of orthopaedic implants. In medical …

Enhanced Light Extraction Efficiency From Gan Light Emitting Diodes Using Photonic Crystal Grating Structures, Simeon S. Trieu

Master's Theses

Gallium nitride (GaN) light emitting diodes (LED) embody a large field of research that aims to replace inefficient, conventional light sources with LEDs that have lower power, higher luminosity, and longer lifetime. This thesis presents an international collaboration effort between the State Key Laboratory for Mesoscopic Physics in Peking University (PKU) of Beijing, China and the Electrical Engineering Department of California Polytechnic State University, San Luis Obispo. Over the course of 2 years, Cal Poly’s side has simulated GaN LEDs within the pure blue wavelength spectrum (460nm), focusing specifically on the effects of reflection gratings, transmission gratings, top and bottom …

Time-Temperature Curing Relationship Of An Adhesive Binder With Rice Straw, Kevin Ka-Wan Ng

Master's Theses

Rice straw is a global and proliferate agricultural waste whose production grossly outstrips viable uses. Current disposal methods are not sustainable, and more convenient methods – such as incineration – exude poor environmental stewardship. Although the direct use of straw bales in building construction presents a practical and sustainable alternative, engineering challenges associated with using it prevent its wide adoption. The Stak Block – a composite formed from compressed rice straw and a heat-cured adhesive – may overcome challenges associated with straw bale building. However, the times and temperatures needed to cure the binder with straw are not well understood. …

Design And Performance Of Load Bearing Shear Walls Made From Composite Rice Straw Blocks, Kevin Robert Camann

Master's Theses

Although rice straw and other grains have been used in building since pre-history, in the past two decades, there has been a move to utilize this rapidly renewable, locally available, agricultural byproduct as part of the sustainable construction movement. Up to this point, this has been done by simply stacking up the full straw bales. Stak Block, invented by Oryzatech, Inc., is a modular, interlocking block made of a composite of rice straw and binding agent that serves as an evolution in straw construction. This study investigates the feasibility of using these Stak Blocks as a structural system. The report …

Feasibility Of Ellipsometric Sensor Development For Use During Pecvd Siox Coated Polymer Product Manufacturing, Daniel Lynn Helms

Master's Theses

Polymeric materials have provided pathways to products that could not be manufactured otherwise. A new technology which merges the benefits of ceramics into these polymer products has created materials ideally suited to many different industries, like food packaging. Nano Scale Surface Systems, Inc. (NS3), a company which coats polymers with ceramic oxides like SiO2 through a process known as plasma enhanced chemical vapor deposition (PECVD), was interested in the feasibility of an in line measurement system for monitoring the deposited films on various polymer products. This project examined two different coated polymer products, polyethylene terephthalate (PET) beverage containers and biaxially …

Assessment Of Electrospinning As An In-House Fabrication Technique For Blood Vessel Mimic Cellular Scaffolding, Colby M. James

Master's Theses

Intravascular devices, such as stents, must be rigorously tested before they can be approved by the FDA. This includes bench top in vitro testing to determine biocompatibility, and animal model testing to ensure safety and efficacy. As an intermediate step, a blood vessel mimic (BVM) testing method has been developed that mimics the three dimensional structure of blood vessels using a perfusion bioreactor system, human derived endothelial cells, and a biocompatible polymer scaffold used to support growth of the blood vessel cells. The focus of this thesis was to find an in-house fabrication method capable of making cellular scaffolding for …

Development Of A Low Cost Handheld Microfluidic Phosphate Colorimeter For Water Quality Analysis, Sean C. Kaylor

Master's Theses

This thesis describes the design, fabrication, and testing process for a microfluidic phosphate colorimeter utilized for water quality analysis. The device can be powered by, and interfaced for data collection with, a common cell phone or laptop to dramatically reduce costs. Unlike commercially available colorimeters, this device does not require the user to measure or mix sample and reagent. A disposable poly(dimethylsiloxane) (PDMS) microfluid chip, powered by an absorption pumping mechanism, was used to draw water samples, mix the sample at a specific ratio with a molybdovanadate reagent, and load both fluids into an onboard cuvette for colorimetric analysis. A …

Design And Development Of Rapid Battery Exchange Systems For Electric Vehicles To Be Used As Efficient Student Transportation, Jonathan A. Bevier

Master's Theses

Rapid battery exchange systems were built for an electric van and pedal assist electric bike as a method of eliminating the need to recharge the vehicles batteries in order to increase the feasibility of using electric propulsion as a method of efficient student transportation. After selecting proper materials it was found that the systems would need a protective coating to ensure consistent operation. 1020 cold rolled steel samples coated with multiple thicknesses of vinyl resin paint, epoxy resin paint, and powder coating were subjected to environmental wear tests in order to determine if the type and thickness of common protective …

The Effect Of Particle Surface Area To Volume Ratio On Ion Release From Cocr Spheres, Darin J. Grandfield

Master's Theses

In 2005, over 200,000 Americans underwent a hip arthroplasty, the replacement of a hip joint with an artificial prosthesis. Of these arthroplasties, metal-on-metal type implants represent an increasing usage percentage. Metal-on-metal implants are selected largely for their low volumetric wear rate, durability, and resistance to corrosion. In spite of these advantages, little is known concerning the long-term consequences of heavy metal alloy use in the body, although early research indicates potentially carcinogenic results. This thesis is a preliminary investigation into these long term effects and their root causes.

An improved comprehension of the corrosion kinetics and the rate of ion …

Evaluating The Electrical Response Of Polyaniline To Mechanical Strain, Matthew L. Goebel

Master's Theses

This thesis focuses on the electrical output of polyaniline films subjected to uniaxial strain in hydrochloric acid solutions. Polyaniline belongs to novel class of materials known as conducting polymers. Alternating single and double bonds in the backbone of conducting polymers allow them to transmit electric charge when they are doped with negatively charged ions. Modifying the degree of doping and other electrical/chemical treatments allow conducting polymers to exhibit conducting, semi-conducting, or insulating electrical properties. Resilient mechanical properties, good processability, and low cost make conducting polymers good candidates for applications traditionally held by metals and semi-conductors.

When tensile strain is applied …

Shielding Effectiveness Of Superalloy, Aluminum, And Mumetal Shielding Tapes, Cindy Suit Cheung

Master's Theses

Using MIL-HDBK-419A, MATLAB and Nomographs, Shielding Effectiveness for the Magnetic Field, Electric Field, and Plane Wave were calculated over a frequency range from 10 Hz to 1 GHz. The three shielding tapes used included superalloy, aluminum, and mumetal. Calculations for Shielding Effectiveness involve the computation of Absorption Loss, Reflection Loss, and Re-Reflection Correction Factor. From the outcome of the calculations, it was suitable to conclude that all three metals fulfill the 40 dB Shielding Effectiveness requirements for SGEMP fields for frequencies greater or equal to 1 MHz. Accordingly, all three shielding tapes provide at least 40 dB of shielding to …

Optimization Of Gan Laser Diodes Using 1d And 2d Optical Simulations, Sean Richard Keali'i Jobe

Master's Theses

This paper studies the optical properties of a GaN Laser Diode (LD). Through simulation, the GaN LD is optimized for the best optical confinement factor. It is found that there are optimal thicknesses of each layer in the diode that yield the highest optical confinement factor. There is a strong relationship between the optical confinement factor and lasing threshold—a higher optical confinement factor results in a lower lasing threshold. Increasing optical confinement improves lasing efficiency. Blue LDs are important to the future of lighting sources as they represent the final color in the RGB spectrum that does not have a …

Potential Migration Of Ε-Caprolactam To Water And Wine As Affected By Transportation And Storage, Joseph C. Ianneo

Master's Theses

Abstract: Under normal sealing and storage conditions, Nylon-6, poly-caprolactam-based plastic laminates may release impurities to packaged foods and liquids and the application of heat for cooking often increases the rate of migration. Epsilon-caprolactam is one of the main contaminates found to migrate from a Nylon-6 poly-caprolactam plastic film. The objectives of this study were to determine the effects of solvent, transportation and storage time on the migration of ε-caprolactam from a Nylon-6-based lidding material into water or a white wine substitute (12% ethanol). Polypropylene plastic cups were filled, sealed, packaged, stacked and exposed to a simulated 3-day cross-country shipment. Cups …

Characterization Of A Viscoelastic Response From Thin Metal Films Deposited On Silicon For Microsystem Applications, Steven L. Meredith

Master's Theses

Understanding the mechanisms that control the mechanical behavior of microscale actuators is necessary to design an actuator that responds to an applied actuation force with the desired behavior. Micro actuators which employ a diaphragm supported by torsional hinges which deform during actuation are used in many applications where device stability and reliability are critical. The material response to the stress developed within the hinge during actuation controls how the actuator will respond to the actuating force. A fully recoverable non-linear viscoelastic response has been observed in electrostatically driven micro actuators employing torsional hinges of silicon covered with thin metal films. …

Effectiveness Of Thermal Oxidation In Relation To Anterior Cervical Plates, Katherine A. Miyashiro

Master's Theses

Ti-6Al-4V anterior cervical plates (ACP) are used in spinal fusion surgeries to fixate cervical vertebrae during graft adhesion. However, documented cases of implant failure and the potential for ACP corrosion raise concerns regarding any degradation of material resulting from extended implantation. In addition, abrasion during implantation may damage a section of the protective oxide layer, potentially exposing surrounding tissues to the harmful effects of bare titanium, aluminum, and vanadium. Thermal oxidation has been shown to improve corrosion-resistance and wear-resistance, depending on temperature and time. To quantify the attributes of the thermally grown oxide layer, Ti-6Al-4V coupons underwent thermal oxidation treatments …

Design, Fabrication, Modeling And Characterization Of Electrostatically-Actuated Silicon Membranes, Brian C. Stahl

Master's Theses

This thesis covers the design, fabrication, modeling and characterization of electrostatically actuated silicon membranes, with applications to microelectromechanical systems (MEMS). A microfabrication process was designed to realize thin membranes etched into a silicon wafer using a wet anisotropic etching process. These flexible membranes were bonded to a rigid counterelectrode using a photo-patterned gap layer. The membranes were actuated electrostatically by applying a voltage bias across the electrode gap formed by the membrane and the counterelectrode, causing the membrane to deflect towards the counterelectrode. This deflection was characterized for a range of actuating voltages and these results were compared to the …

Design, Fabrication, And Characterization Of An Electrostatically Actuated Microfluidic Valve, Ryan Dale Rivers

Master's Theses

Microfluidic device construction uses certain critical structures throughout many different applications. The valve structure remains one of the primary structures that present a barrier to miniaturization and portability. The extensive support devices required to power common microfluidic valves remove a significant amount of freedom from microfluidic device design. Moving to electrostatic methods of actuation could reduce the overall footprint of the microfluidic valve. This thesis covers three concept prototypes. Concept I presents an attempt at inlaying gold electrodes into polydimethylsiloxane substrates. Concept II attempts to use liquid silver injected into channels as electrode materials. Concept III uses aluminum sputtering to …