Engineering Commons^™

Shape Memory Alloy Capsule Micropump For Drug Delivery Applications, Youssef Mohamed Kotb

Theses and Dissertations

Implantable drug delivery devices have many benefits over traditional drug administration techniques and have attracted a lot of attention in recent years. By delivering the medication directly to the tissue, they enable the use of larger localized concentrations, enhancing the efficacy of the treatment. Passive-release drug delivery systems, one of the various ways to provide medication, are great inventions. However, they cannot dispense the medication on demand since they are nonprogrammable. Therefore, active actuators are more advantageous in delivery applications. Smart material actuators, however, have greatly increased in popularity for manufacturing wearable and implantable micropumps due to their high energy …

Properties Of Portland Cement Concrete Incorporating Basalt-Based Pozzolanic Cement, Rana Khalil

Theses and Dissertations

Over the last decade, the world's population has increased dramatically. Due to this growth, the demand for concrete and Portland cement, in return, have increased. Manufacturing of Portland cement is an energy-intensive process that, alone, contributes to about 8% of global CO2. For decades, efforts have been exerted to reduce the harmful environmental impacts of Portland cement by reducing its use in concrete as well as considering alternate binders that may fully or partially replace it. This study aims to assess the properties of concrete incorporating a novel basalt-based pozzolanic cement. To meet this objective, four sets of concrete mixtures …

Extrusion-Based Additive Manufacturing Of Magnetic Heat Exchange Structures For Caloric Applications, Vaibhav Sharma

Theses and Dissertations

Currently, the commercial building sector accounts for 18% of total U.S. end-use energy consumption, of which almost a third was from on-site combustion of fossil fuels for space and water heating. Magnetic heat pumping (MHP) technology is an energy-efficient, sustainable, environmentally-friendly alternative to conventional vapor-compression cooling technology. Several MHP designs today are predicted to be highly energy efficient, on condition that suitable working materials can be developed. This materials challenge has proven to be daunting due to issues associated with intricate synthesis/post-processing protocols and complications related to shaping the mostly brittle magnetocaloric alloys into thin-walled channeled regenerator structures to facilitate …

Analyzing The Effects Of Ultrafast Laser Processing On Mechanical Properties Of 3d-Printed Pla Parts, Darshan Pramodbhai Yadav

Theses and Dissertations

Recent advances in additive manufacturing technologies have already led to wide-scale adoption of 3D-printed parts in various industries. The expansion in choice of materials that can be processed, particularly using Fused Deposition Modeling (FDM), and the steady advancements in dimensional accuracy control have extended the range of applications far beyond rapid prototyping. However, additive manufacturing still has considerable limitations compared to traditional and subtractive manufacturing processes. This work addresses limitations associated with the as-deposited surface roughness of 3D-printed parts. The effects of roughness-induced stress concentrations were studied on ultimate tensile strength and fatigue life. The samples were manufactured using a …

Integrating Steel Slag Aggregates Into Asphalt Paving By Harmonizing Availability, Quality, Economics, And The Environment, Timothy R. Murphy

Theses and Dissertations

This thesis provides guidance on how to balance matters related to the environmental stewardship, market sources, origin and uses, material properties, performance, and economic impact of using slag materials in pavements. The literature on this topic provides numerous references on the use of slag materials for specific applications, and this thesis aims to make use of those references along with other data from the author to describe slag materials from a holistic perspective and provide some suggestions for balancing several factors that impact optimal use of this resource within pavement structures. Discussion is given to the increased importance of recycling …

Influence Of Processed Natural Black Sand Vs. Natural White Sand And Silica Flour As Additives To Oil-Well Cementing Applications, Ramy Abuel Maaty

Theses and Dissertations

Cementing is a crucial and fundamental step in the process of drilling wells to extract oil from its reservoirs. Cementing main functions are to achieve zonal isolation and provide mechanical support to the casing. Impermeable and powerful cement is strongly desired to withstand high pressures and temperatures during the lifetime of the producing wells. Various additives to cement, such as silica flour, fly ash, Nano-additives and other advanced materials have been used and tested to attain improved cement of higher quality and enhanced properties such as permeability, porosity, mechanical and rheological properties. Very few researches have discussed the uses of …

Challenges And Signal Processing Of High Strain Rate Mechanical Testing, Barae Lamdini

Theses and Dissertations

Dynamic testing provides valuable insight into the behavior of materials undergoing fast deformation. During Split-Hopkinson Pressure Bar testing, stress waves are measured using strain gauges as voltage variations that are usually very small. Therefore, an amplifier is required to amplify the data and analyze it. One of the few available amplifiers designed for this purpose is provided by Vishay Micro-Measurements which limits the user’s options when it comes to research or industry. Among the challenges of implementing the Hopkinson technology in the industry are the size and cost of the amplifier. In this work, we propose a novel design of …

Electromechanical Fatigue Properties Of Dielectric Elastomer Stretch Sensors Under Orthopaedic Loading Conditions, Andrea Karen Persons

Theses and Dissertations

Fatigue testing of stretch sensors often focuses on high amplitude, low-cycle fatigue (LCF) behavior; however, when used for orthopaedic, athletic, or ergonomic assessments, stretch sensors are subjected to low amplitude, high-cycle fatigue (HCF) conditions. As an added layer of complexity, the fatigue testing of stretch sensors is not only focused on the life of the material comprising the sensor, but also on the reliability of the signal produced during the extension and relaxation of the sensor. Research into the development of a smart sock that can be used to measure the range of motion (ROM) of the ankle joint during …

Design And Testing Of A Composite Compressor Rotor, Mauro Noel V. De Leon

Theses and Dissertations

Additive manufacturing (AM) and molding are manufacturing methods known for building representations or replicas of conceptualized engine components, but was considered impractical for manufacturing operating engine components. More recent technology has rendered composite materials (combining high-temperature polymers and fiber reinforcement) capable of withstanding the temperature and structural requirements to compete with conventional turbomachinery metals. This study explores the application of several high-temperature polymers (ULTEM 9085, Onyx-Carbon fiber, and Epoxy-Carbon fiber) and their survivability in the operating conditions of a P400 Engine compressor. The tests conducted for this study determined their viability as compressor materials. This study required conducting tensile specimen …

A Study On The Early Stages Of Degradation Of Multi-Component Alloy Surfaces In Extreme Environments Using The Multi-Cell Monte Carlo Method, Tyler D. Dolezal

Theses and Dissertations

A computational toolset is presented and used in two examples that examined the interactions between structural materials and their extreme environments. A multi-cell Monte Carlo algorithm was developed to generate thermodynamically realistic solid-state alloy systems. These structures served as the foundation upon which surface slab models were generated. The tedious procedure of generating surface slab models from bulk structures was automated. The tools were used to study the high temperature surface corrosion resistance of a high-entropy alloy, Al₁₀Nb₁₅Ta₅Ti₃₀Zr₄₀, and a nickel-based alloy, Ni₇₀Nb₁₀W₂₀, under …

Thermal Relaxation Of Shot Peen Induced Residual Stresses In A Nickel-Base Superalloy, Bryce E. Van Velson

Theses and Dissertations

Shot peening induces compressive residual stresses in components that positively influence fatigue life. Thermal and mechanical loading causes those residual stresses to relax. The hole drilling method and xray diffraction is used to measure the thermal relaxation of residual stresses in the nickel-base superalloy ME3.

Rational Design Of Flexible And Stretchable Electronics Based On 3d Printing, Yuanhang Yang

Theses and Dissertations

Flexible and stretchable electronics have been considered as the key component for the next generation of flexible devices. There are many approaches to prepare the devices, such as dip coating, spin coating, Mayer bar coating, filtration and transfer, and printing, etc. The effectiveness of these methods has been proven, but some drawbacks cannot be ignored, such as lacking pattern control, labor consuming, requiring complex pretreatment, wasting conductive materials, etc.

In this investigation, we propose to adopt 3D printing technology to design flexible and stretchable electronics. The objective is to rationally design flexible and stretchable sensors, simplify the preparation process, form …

Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear

Theses and Dissertations

Several additively manufactured lattice designs and configurations were evaluated under compression loads under various strain rates from quasi-static to highly dynamic. These experiments examined how the mechanical behavior of the lattice changed based on the lattice design properties and the applied strain rates. The modulus of elasticity, yield strength, plateau stress, and toughness were observed to decrease with an increase in strain rate, revealing that the lattice designs exhibit a negative strain rate sensitivity. A new lattice flow stress model was developed to account for the mechanical response of the lattice and was incorporated into a computational model for simulation. …

Fluid-Structure Interaction Of Nrel 5-Mw Wind Turbine, Mohamed Sayed Elkady Abd-Elhay

Theses and Dissertations

Wind energy is considered one of the major sources of renewable energy. Nowadays, wind turbine blades could exceed 100 m to maximize the generated power and minimize produced energy cost. Due to the enormous size of the wind turbines, the blades are subjected to failure by aerodynamics loads or instability issues. Also, the gravitational and centrifugal loads affect the wind turbine design because of the huge mass of the blades. Accordingly, wind turbine simulation became efficient in blade design to reduce the cost of its manufacturing. The fluid-structure interaction (FSI) is considered an effective way to study the turbine's behavior …

Shock Migration On An Oscillating Straked Delta Wing Using An Unsteady Euler Solver, Alexander J. Brown

Theses and Dissertations

This research contributes to the understanding of Shock Induced Trailing Edge Separation (SITES) as a driver of Limit Cycle Oscillation (LCO) by performing a computational investigation of nonlinear aerodynamic phenomena on a straked delta wing in transonic flow, oscillating in pitch. ZEUS, an Euler-based aeroelastic solver with a boundary layer coupling scheme meant to capture viscous flow effects within the boundary layer, was used to analyze aerodynamic flow around the wing for various mean incidence angles, oscillation amplitudes, and Mach numbers within the transonic region. The dynamic characteristics of the airflow around the wing were investigated in order to characterize …

A Computational Study Of Cocrfeniti High Entropy Alloys: Phase Diagrams, Thermodynamics, And Mechanical Properties From Calphad And First Principles, Geraldine Anis

Theses and Dissertations

High entropy alloys (HEAs) are multi-component alloys, which are often defined as those consisting of at least 5 principal elements with concentrations ranging between 5 and 35 atomic weight percent (at.%). Since their introduction by Yeh et al. and Cantor et al. in 2004, HEAs have been found to possess many important properties and have become prime candidates for several high-performance applications such as high-temperature and biomedical applications. Despite their multi-principal element nature, many HEAs favor the formation of solid solution phases as opposed to the intermetallic phases expected for such systems. This was originally only attributed to their high …

Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer

Theses and Dissertations

Composite materials are strong, lightweight, and stiff making them desirable in aerospace applications. However, a practical issue arises with composites in that they behave unpredictably in bolted joints, where damage and cracks are often initiated. This research investigated a solution to correcting the problem with composite bolted joints. A novel hybrid composite material was developed, where thin stainless steel foils were placed between and in place of preimpregnated composite plies during the cure cycle to reinforce stress concentrations in bolted joints. This novel composite was compared to control samples experimentally in quasi-static monotonic loading in double shear configuration in 9-ply …

Tension-Tension Fatigue Behavior Of Nextel™ 720/Alumina-Mullite Ceramic Composite At 1200°C In Air And In Steam, Sarah A. Witzgall

Theses and Dissertations

Uniaxial tension-tension fatigue performance of an oxide-oxide continuous fiber ceramic composite was studied at 1200°C in laboratory air and in steam. The composite is reinforced with laminated, 0/90 mullite/alumina (NEXTEL™720) fibers woven in an eight-harness satin weave and has a porous alumina/mullite matrix. There is no interphase between the fiber and matrix. The composite relies on the porous matrix for crack deflection and flaw tolerance. Tension-tension fatigue was examined for maximum stresses of 45 – 136 MPa in air and in steam. To assess the effects of the steam environment on fatigue performance, experimental results obtained in air are compared …

Modeling Nonlinear Heat Transfer For A Pin-On-Disc Sliding System, Brian A. Boardman

Theses and Dissertations

The objective of this research is to develop a numerical method to characterize heat transfer and wear rates for samples of Vascomax® 300, or Maraging 300, steel. A pin-on-disc experiment was conducted in which samples were exposed to a high-pressure, high-speed, sliding contact environment. This sliding contact generates frictional heating that influences the temperature distribution and wear characteristics of the test samples. A two-dimensional nonlinear heat transfer equation is discretized and solved via a second-order explicit finite difference scheme to predict the transient temperature distribution of the pin. This schematic is used to predict the removal of material from the …

Focused Beam System Biaxial Material Characterization, Nicholas A. O'Gorman

Theses and Dissertations

Electromagnetic material characterization is the process of determining the constitutive parameters (complex permittivity and permeability) of given a sample. Due to the large number of unknowns involved, multiple unique measurements are required for material property extraction. Many measurement methods, such as waveguides and striplines, possess a rigid internal structure that the sample being measured must adhere to. This rigidity limits these methods to samples that fit within the device and inhibits oblique sample orientations, limiting the number of independent measurements that can be obtained. A focus beam system, due to being an open system with greater freedom in sample size …

Structural Dynamic And Inherent Damping Characterization Of Additively Manufactured Airfoil Components, Andrew W. Goldin

Theses and Dissertations

The push for low cost and higher performance/efficient turbine engines have introduced a new demand for novel technologies to improve robustness to vibrations resulting in High Cycle Fatigue (HCF). There have been many proposed solutions to this, some passive and some active. With the advent of Additive Manufacturing (AM), new damping techniques can now be incorporated directly into the design and manufacture process to suppress the vibrations that create HCF. In this study, this novel unfused pocket damping technology is applied to a blade structure and the resulting damping effectiveness is quantified. The application of this technology to complex geometries …

Fatigue Behavior Of An Advanced Melt-Infiltrated Sic/Sic Composite With Environmental Barrier Coating At 1200°C In Air And In Steam, Thaddeus M. Williams

Theses and Dissertations

Advanced aerospace applications such as aircraft turbine engine components, hypersonic flight vehicles, and spacecraft reentry thermal protection systems require structural materials that have superior long-term mechanical properties under high temperature, high pressure, and varying environmental factors, such as moisture. Because of their low density, high strength and fracture toughness at high temperatures SiC fiber-reinforced SiC matrix composites are being evaluated for aircraft engine hot-section components. In these applications the composites will be subjected to various types of mechanical loadings at elevated temperatures in oxidizing environments. Because their constituents are intrinsically oxidation-prone, the most significant problem hindering SiC/SiC composites is oxidation …

Generation Of Warm Dense Plasma On Solar Panel Infrastructure In Exo-Atmospheric Conditions, Harrison C. Wenzel

Theses and Dissertations

The use of a weaponized thermo-nuclear device in exo-atmospheric conditions would be of great impact on the material integrity of orbiting satellite infrastructure. Particular damage would occur to the multi-layered, solar cell components of such satellites. The rapid absorption of X-ray radiation originating from a nuclear blast into these layers occurs over a picosecond time scale and leads to the generation of Warm Dense Plasma (WDP). While incredibly difficult and costly to replicate in a laboratory setting, a collection of computational techniques and software libraries may be utilized to simulate the intricate atomic and subatomic physics characteristics of such an …

Effects Of Carbon-Based Ablation Products On Hypersonic Boundary Layer Stability, Olivia S. Elliott

Theses and Dissertations

Hypersonic vehicles require an accurate prediction of the transition of the boundary layer for the design of the thermal protection system due to the high heating rates under turbulent flow. Many thermal protection systems are carbon-based and introduce new species, specifically CO₂, into the boundary layer flow which are known to dampen the instabilities that lead to transition for hypersonic vehicles. A Computation Fluid Dynamics study was accomplished examining the concentration of CO₂ required to impact boundary layer transition over both sharp and blunt cones. These results were used in conjunction with air-carbon ablation models models to …

On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom

Theses and Dissertations

This dissertation covers pulsed laser ablation of Al, Si, Ti, Ge, and InSb, with pulse durations from tens of picosecond to hundreds of microseconds, fluences from ones of J/cm² to over 10,000 J/cm², and in ambient air and vacuum. A set of non-dimensional scaling factors was created to interpret the data relative to the laser and material parameters, and it was found that pulse durations shorter than a critical timescale formed craters much larger than the thermal diffusion length, and longer pulse durations created holes much shallower than the thermal diffusion length. Low transverse order Gaussian beams …

Influence Of Leading Edge Oscillatory Blowing On Time-Accurate Dynamic Store Separation, Ryan G. Saunders

Theses and Dissertations

The primary objective of this research is to support the static and dynamic characterization and the time-accurate dynamic load data acquisition of store separation from a cavity with leading edge oscillatory blowing. Developing an understanding of, and potentially controlling, pitch bifurcation of a store release is a motivation for this research. The apparatus and data acquisition system was used in a two-part experiment to collect both static and dynamic testing data in the AFIT low speed wind tunnel in speeds of 60, 100, and 120 mph, from Reynolds numbers varying from 5.5x10⁴ to 4.6x10⁵, depending on reference …

Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt

Theses and Dissertations

Wind tunnels play an indispensable role in the process of aircraft design, providing a test bed to produce valuable, accurate data that can be extrapolated to actual flight conditions. Historically, time-averaged data has made up the bulk of wind tunnel research, but modern flight design necessitates the use of dynamic wind tunnel testing to provide time-accurate data for high frequency motion. This research explores the use of a 6 degree of freedom (DOF) motion test apparatus (MTA) in the form of a robotic arm to allow models inside a subsonic wind tunnel to track prescribed trajectories to obtain time-accurate force …

Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung

Theses and Dissertations

A recent research effort, sponsored by the Air Force Office of Scientific Research, numerically investigated the unsteady aerodynamic flow field around an oscillating, straked, delta wing. The study was centered on determining the importance of the unsteady aerodynamic forces acting as a driver for a nonlinear motion known as limit cycle oscillations. The current effort focused on creating a computational model to compare to the results of previous tests and modeling efforts and discover new information regarding the onset of LCO. The computational model was constructed using the Cartesian overset capabilities of the CREATE-AV™ fixed wing fluid dynamics solver Kestrel. …

Ballistic Evaluation Of Carbon Nanotube Sheet Material In Multifunctional Applications, Casey M. Keilbarth

Theses and Dissertations

Significant development of carbon nanotubes has occurred since they were first studied in the 1990's. Attempts to capture the phenomenal molecular properties in practical applications are gaining ground as new methods of producing CNTs have been developed. This thesis sought to determine if the addition of commercially produced CNT sheets to thin carbon fiber panels improved the ballistic properties of the panel. The difference between 0 and 4 CNT sheets was studied. The hypothesis was that inte- grating CNT sheets into the laminate would increase the projectile energy absorbed by the panel and reduce the damage to the panel incurred …

Computational Aerothermodynamic Analysis Of Satellite Trans-Atmospheric Skip Entry Survivability, John J. Runco

Theses and Dissertations

Computational aerothermodynamic analysis is presented for a spacecraft in low Earth orbit performing an atmospheric skip entry maneuver. Typically, atmospheric reentry is a terminal operation signaling mission end-of-life and, in some instances, executed for spacecraft disposal. A variation on reentry – skip entry – is an aeroassisted trans-atmospheric maneuver in which a spacecraft utilizes the effects of aerodynamic drag in order to reduce energy prior to a terminal entry, pinpoint a targeted entry, or change orbital elements such as inclination. Spacecraft performing a skip entry enable new modes of maneuver to enhance operations in nominal or possibly contested mission environments. …