Engineering Commons^™

Modeling, Simulation, And Validation Of Process-Structure-Property Relationships In Fused Filament Fabrication, Aaron Grant

Electronic Theses and Dissertations

As additive manufacturing (AM) grows in popularity, the need for better simulation tools to predict the process-structure-property relationships of AM parts becomes ever more necessary to employ the technology in design of functional parts with varying degrees of complexity and performance requirements. Many simulation tools and techniques have been developed that aim to achieve this goal, and the main purpose of this research is to explore how well different simulation tools and modeling approaches can capture various AM-specific features such as inter-raster and end-of raster voids, and residual stresses induced by dissimilar rates of thermal expansion. Process simulation of fused …

Damage Resistance And Tolerance Of 3d Woven Composites, Justin T. Mcdermott

Electronic Theses and Dissertations

Composite materials have been adopted into primary aircraft structures by virtue of their great strength-to-weight and stiffness-to-weight ratios, fatigue insensitivity, and corrosion resistance. These characteristics are leveraged by aircraft designers to deliver improved fuel effciency and reduced scheduled maintenance burdens for their customers. These benefits have been impressively realized in the Boeing 787 and Airbus A350 XWB, with airframes utilizing about 50% composites by weight. Tempering these successes, however, are the inherent vulnerabilities of carbon-fiber reinforced composites. When compared to conventional metallic structure, composite laminates are more sensitive to stress concentrations at mechanical fastenings and damage due to low-velocity impact. …

Development And Characterization Of A Biopolymer Direct-Write Process For 3d Microvascular Structures Formation., Xiaoming Fan

Electronic Theses and Dissertations

Engineering of bulk tissues has been limited by the lack of nutrient and waste exchange in these tissues without an adjacent capillary network. To produce microvasculature, a scaffold must be produced that provides temporary mechanical support and stimulate endothelial cell adhesion, growth, and morphogenesis into a vessel. However, current well-established techniques for producing microvasculature, such as electrospinning, are limited since they lack both the precision to control fiber placement in three-dimensional space and the ability to create fiber networks with predefined diameters to replicate the physiological microvascular progression from arteriole to capillary to venule. Our group has developed a “Direct-write” …

Design, Analysis, And Optimization Of Compactible Origami-Inspired Shelters, Anthony M. Verzoni

Electronic Theses and Dissertations

Origami-inspired design is a growing field with numerous engineering applications, including rapidly compactable and erectable shelters with nondeformed flat panels, which are considered in this research. Shelter geometry is controlled by the shape, size, and connectivity of individual panels that must fold and unfold in a kinematically compliant manner resulting in no panel intersection. Panel size and shape are altered to yield shelter designs with varying volumetric capacities. Thin panels are initially used to study the kinematics of shelter concepts as traditional origami. With increasing panel thickness, the location of fold or hinge lines exerts a large influence on the …

Fluid Flow Analysis Of Diluted Evaporating American Whiskey Droplets., Martin J. Brown Vi

Electronic Theses and Dissertations

The recent discovery of the unique structures, whiskey webs, formed when the evaporation of diluted American whiskey, has raised many questions as to the nature of the structures. Their formation process follows as such: (1) dilution of the whiskey to form nanoaggregates, (2) formation of a monolayer at the air-liquid interface, (3) chaotic ethanol evaporation caused monolayer collapse (via dynamic pressure), (4) bulk fluid evaporation caused monolayer collapse (via reduction of surface area), where the web-like structures reside on the surface, and finally, (5) web-like structures deposit on the substrate. The webs imaged via SEM had a striking resemblance to …

All Season Heat Pipe System., Adrienne Marie Parsons

Electronic Theses and Dissertations

Our energy choices impact the earth’s natural systems and climate. As this becomes increasingly important, the need for decreasing our energy usage is essential. Conventional passive solar systems can significantly reduce the heating load. Similarly, passive ambient energy systems, such as ventilation and sky radiation, can reduce cooling loads. However, the integration of passive heating and cooling systems in the same building and the benefits of actively controlling these otherwise passive systems to maximize annual energy savings has largely been unexplored. This study first evaluates the building cooling capacity of sky radiation, which was previously identified to have the greatest …

Improving Flow-Induced Hemolysis Prediction Models., Mohammad Mohaghegh Faghih

Electronic Theses and Dissertations

Partial or complete failure of red blood cell membrane, also known as hemolysis, is a persistent issue with almost all blood contacting devices. Many experimental and theoretical contributions over the last few decades have increased insight into the mechanisms of mechanical hemolysis in both laminar and turbulent flow regimes, with the ultimate goal of developing a comprehensive, mechanistic and universal hemolysis prediction model. My research is broadly divided into two sections: theoretical/analytical/Computational Fluid Dynamics (CFD) analyses and experimental tests. The first part of my research revolved entirely around analyzing the simplest and most popular hemolysis model, commonly called as the …

Global Performance Testing, Simulation, And Optimization Of A 6-Mw Annular Floating Offshore Wind Turbine Hull, Hannah L. Allen

Electronic Theses and Dissertations

Floating offshore wind turbine (FOWT) hull technologies are evolving rapidly with many technically viable designs. However, a commercially dominant architecture has yet to emerge. This thesis presents a methodology for evaluation of the hydrodynamic performance of an annular FOWT hull. This hull shows significant promise from a manufacturing and installation standpoint, but limited performance data exists. This thesis will provide ample documentation on scale model testing of an annular FOWT hull as well as the corresponding numerical validation approach and opportunities for design improvement.

The first portion of this work involves testing a 1/100th-scale model in the Harold Alfond Wind …

Dynamic Behavior And Performance Of Different Types Of Multi-Effect Desalination Plants, Mohamed Abdelkareem

Electronic Theses and Dissertations

Water and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of primary energy and electricity consumption compared to other thermal desalination systems. The motivation for this research is to address thermo-economics and dynamic behavior …

Mechanical Properties Of Brittle Ceramics: Case Study Of Boron Rich Ceramics And Acropora Cervicornis Coral Skeleton, Alejandro Carrasco-Pena

Electronic Theses and Dissertations

Ceramics are ubiquitous in man-made and natural structures. Their mechanical properties highly depend on their composition, microstructure and level of defects in the bulk of the material, the latter affecting the integrity of the components; such is the case of boron-rich ceramics where large agglomerates create high stressed regions, or coral skeleton where porosity determines their strength against hydrodynamic forces present in the ocean tides. Therefore, studying the properties of ceramic materials using invasive and non-invasive methods helps in the understanding of the link between the properties and the performance of the structures. The aim of this research was to …

Vibration Reduction Of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning, Garrett Lopp

Electronic Theses and Dissertations

Recent trends in turbomachinery blade technology have led to increased use of monolithically constructed bladed disks (blisks). Although offering a wealth of performance benefits, this construction removes the blade-attachment interface present in the conventional design, thus unintentionally removing a source of friction-based damping needed to counteract large vibrations during resonance passages. This issue is further exacerbated in the presence of blade mistuning that arises from small imperfections from otherwise identical blades and are unavoidable as they originate from manufacturing tolerances and operational wear over the lifespan of the engine. Mistuning is known to induce vibration localization with large vibration amplitudes …

Development Of A Single Sensor Approach For Capturing Three-Dimensional, Time Resolved Flame And Velocity Information, Jonathan Reyes

Electronic Theses and Dissertations

Performing non-intrusive measurements is the key to acquiring accurate information representative of what is being observed. The act of measuring often changes the environment being observed altering the information that is being obtained. Due to this, the community of fluid scientists have gravitated towards using laser-based measurements to observe the phenomena occurring in their experiments. The study of fluids has advanced since this point, utilizing techniques such as planar laser induced florescence (PLIF), particle image velocimetry (PIV), laser doppler velocimetry (LDV), particle doppler anemometry (PDA), etc. to acquire chemical species information and velocity information. These techniques, though, are inherently two-dimensional …

Decentralized Consensus-Based Control Allocation For Some Dynamical Systems, August Mark

Electronic Theses and Dissertations

In this dissertation, three separate studies, wherein techniques from graph theory and consensus control are used to address control allocation problems, are presented. In the first study, a decentralized allocator is presented for synthetic jet actuators and control surfaces onboard a small unmanned aerial vehicle to cooperatively generate desired aerodynamic moments. First order linear dynamics are assumed for both the synthetic jet actuators and control surfaces. A weighted consensus algorithm with limited feedback is used for the aerodynamic moment contribution allocator considering constraints. In the second study, the same allocation problem as in the first study is considered, but the …

Variable Fluid Flow Regimes Alter Endothelial Adherens Junctions And Tight Junctions, Dilshan Ranadewa

Electronic Theses and Dissertations

Variable blood flow regimes influence a range of cellular properties ranging from cell orientation, shape, and permeability: all of which are dependent on endothelial cell-cell junctions. In fact, cell-cell junctions have shown to be an integral part of vascular homeostasis through the endothelium by allowing intercellular signaling and passage control through tight junctions (TJs), adherens junctions (AJs), and gap junctions (GJs). It was our objective to determine the structural response of both AJs and TJs under steady and oscillatory flow. Human brain microvascular endothelial cells (HBMECs) were cultured in a parallel plate flow chamber and exposed to separate trails of …

Lithium Molybdate-Sulfur Battery., Ruchira Ravinath Dharmasena

Electronic Theses and Dissertations

Rechargeable energy storage systems play a vital role in today’s automobile industry with the emergence of electric vehicles (EVs). In order to meet the targets set by the department of energy (DOE), there is an immediate need of new battery chemistries with higher energy density than the current Li- ion technology. Lithium–sulfur (Li–S) batteries have attracted enormous attention in the energy-storage, due to their high specific energy density of 2600 Wh kg^-1 and operational voltage of 2.0 V. Despite the promising electrochemical characteristics, Li-S batteries suffer from serious technical challenges such as dissolution of polysulfides Li₂S_{x …}

A Study On Ultrasonic Energy Assisted Metal Processing : Its Correeltion With Microstructure And Properties, And Its Application To Additive Manufacturing., Anagh Deshpande

Electronic Theses and Dissertations

Additive manufacturing or 3d printing is the process of constructing a 3-dimensional object layer-by-layer. This additive approach to manufacturing has enabled fabrication of complex components directly from a computer model (or a CAD model). The process has now matured from its earlier version of being a rapid prototyping tool to a technology that can fabricate service-ready components. Development of low-cost polymer additive manufacturing printers enabled by open source Fused Deposition Modeling (FDM) printers and printers of other technologies like SLA and binder jetting has made polymer additive manufacturing accessible and affordable. But the metal additive manufacturing technologies are still expensive …

Numerical Investigation Of Coalescence-Induced Self-Propelled Behavior Of Droplets On Non-Wetting Surfaces And Wedged Surfaces., Yan Chen

Electronic Theses and Dissertations

When small drops coalesce on a superhydrophobic surface, the merged drop can jump away from the surface due to the surface energy released during the coalescence. This self-propelled behavior has been observed on various superhydrophobic surfaces and has potential applications in areas related to the heat and mass transfer, such as heat exchangers, anti-icing and anti-frost devices, thermal management and water harvesting. The jumping velocity model was obtained based on published experimental data and the balance of various energy terms described in previous studies. However, the self-propelled mechanism is still not fully understood. In this study, the self-propelled droplet phenomenon …

Experimental Investigation Of The Manufacture Of Tunable Graphene Oxide Filter Membranes Using Intense Pulse Light, Joshua H Kotter

Electronic Theses and Dissertations

Reduced graphene oxide is a thin, strong, and inexpensive material with a channel and pore structure that make it a promising candidate for a filtration material. Reduced graphene oxide has been produced and tested in the laboratory, but a lack of scalable manufacturing techniques have limited its commercial use.

This thesis has shown that graphene oxide can be rapidly manufactured with an industrially scalable flash reduction process. The flash reduction process uses 0.58 millisecond pulses from a xenon lamp to reduce the graphene oxide film in less than a minute. Results for partially reduced graphene oxide membranes tuned by the …

A Study Of Organo-Phosphorous Simulants Thermal Destruction Using Shock Tube/Laser Diagnostics Techniques And Chemical Kinetics Modeling, Sneha Neupane

Electronic Theses and Dissertations

High-fidelity chemical kinetic models are critical in predictive modeling during design and optimization of next generation energy systems. Shock tube provides an ideal tool to investigate high-temperature chemical kinetics. Non-intrusive laser absorption diagnostics provide in-situ measurements of quantitative, time-resolved species concentration data in this complex chemically reacting system. In this work, shock tube and laser absorption spectroscopy were utilized to measure species concentration time-histories during pyrolysis and oxidation of organo-phosphorous compounds (OPCs). The experiments data obtained were used as benchmark to develop an improved kinetic model of OPCs combustion. Interest in combustion chemistry of OPCs is associated to their use …

Static Load Bolted Joint Elastic Resilience Testing Methodology, Paul Melino

Electronic Theses and Dissertations

Elastic resilience is the ratio of deformation over force an object experiences when under stress. Knowing the how much the bolt and clamped part deform under load is critical when determining fasteners for a bolted joint. VDI 2230 is the internationally recognized bolt sizing standard and contains the equations used to determine each of the bolted joint component’s resilience as well as values for embedment estimates based on component surface roughness. Embedment is the local plastic deformation due to uneven contact over the contact planes of a bolt-clamped interface (Bolt head to plate, plate to plate, plate to nut, and …

3d Printed Bioreactor With Optimized Stimulations For Ex-Vivo Bone Tissue Culture, Anirban Chakraborty

Electronic Theses and Dissertations

Motivation: Long term tissue survivability ex-vivo can greatly facilitate research on the influence of external stimulus (loading, radiation, microgravity) on the tissue, including mechanisms of disease transmission and subsequent drug discoveries. Bioreactors (used to culture living tissue ex-vivo) can be a valuable tool to study cell activity during physiological processes by mimicking their in-vivo native 3D environment.
Objective Statement: We have developed a compact, 3D printed bioreactor equipped with both continuous flow-perfusion and dynamic mechanical-loading stimulations, capable of maintaining ex-vivo viability of swine cancellous bone cores over a long period. Qualitative study of the cultured cores (in terms of …

Flexure Properties Of 3d Printed Nylon Carbon Fiber Composite And Stiffness Of 3d Printed Modified Cuttlefish Bone Structure, Shashikanth Reddy

Electronic Theses and Dissertations

Flexure strength is one of the most widely used mechanical properties to represent the mechanical behavior of the composite. Fiber reinforcements increase the flexure strength of a composite. Specifically, there has been tremendous growth in the use of Carbon Fiber (CF) in the manufacturing industry due to its significant contribution to enhance the mechanical properties of a composite. Fiber orientation, void content, bonding between the layers (delamination), and fiber distribution are some of the factors that affect the flexure strength of a reinforced composite. The laminate (composite with reinforced layers) composites, has been a focus of study by researchers from …

Modeling And Study Of Thermal Effects On Battery Pack Using Phase Change Materials, Umang Selokar

Electronic Theses and Dissertations

The scope of the current research is to reduce the temperature distribution area in Li-ion cell and the battery pack with respect to time in battery design, using CFD technology (Computational Fluid Dynamics) in ANSYS fluent. A 3D model was design in CAD software (CATIA) and analyzed in ANSYS fluent to study the thermal behavior of the designed battery pack. An analytical thermal model was generated to evaluate the heat generation rate passing throughout the battery pack. The battery pack were analyzed and simulated on two different designs. One battery design is modeled with and without insulation (superwool EST compression …

A Theoretical, Numerical, And Experimental Study Of Trapped Droplet Coalescence And Mixing, Passively And Under Electric Field, Alireza Karbalaei Baba

Electronic Theses and Dissertations

Passive and electrically active coalescence and mixing of pairs of trapped squeezed nanodroplets were studied in this work. PDMS-glass microfluidic devices were designed and fabricated using multilevel photolithography technique. Flow-focusing method was used to generate nanoliter droplets of died glycerol inside oleic acid. The effect of factors such as flow rates and their ratio, interfacial tension, and viscosities on the size and frequency of droplet generation was studied and concluded by demonstrating the capillary number effect. A passive droplet trapping technique based on minimizing the surface energy of the droplets was employed to minimize the shear flow effects and increase …

Modeling And Transient Simulation Of A Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000, Jonathan Mcconnell

Electronic Theses and Dissertations

The focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids have brought forth a necessity to gain a comprehensive understanding of transient behavior within an HRSG in order to efficiently manage …

Fluid Flow Characteristics Of A Co-Flow Fluidic Slot Jet Thrust Augmentation Propulsion System, Brian Garrett

Electronic Theses and Dissertations

The UAV industry is booming with investments in research and development on improving UAV systems in order to increase applications and reduce costs of the use of these machines. Current UAV machines are developed according to the quadcopter design which has a rotary propulsion system which provides the lift needed for the aerial vehicles. This design has some flaws; namely safety concerns and noise/vibration production both of which come from the rotary propulsion system. As such, a novel propulsion system using slip stream air passed through high performance slot jets is proposed and analysis of the fluid characteristics is presented …

Cavitation And Heat Transfer Over Micro Pin Fins, Arash Nayebzadeh

Electronic Theses and Dissertations

With the dramatic increase in the usage of compact yet more powerful electronic devices, advanced cooling technologies are required to maintain delicate electronic components below their maximum allowable temperatures and prevent them from failure. One solution is to use innovative pin finned heat sinks. This research is centered on the evaluation of hydrodynamic cavitation properties downstream pin fins and extended toward single-phase heat transfer enhancement of array of pin fins in microchannel. In this work, transparent micro-devices capable of local wall temperature measurements were micro fabricated and tested. Various experimental methods, numerical modeling and advanced data processing techniques are presented. …

Investigation Of Flow Field Structures In A Rectangular Channel With A Pin Fin Array, Patrick Tran

Electronic Theses and Dissertations

Pin fin arrays are commonly found in heat exchangers, turbine blades, and electronic heat sinks. Fin arrays are extended surfaces that are used as turbulence promoters by inducing horseshoe vortex (HSV) and von Karman vortex (KV) structures. The horseshoe vortex are primarily studied in the leading edge of the blunt body, whereas the KV are formed in the trailing side. This study presents an experimental investigation of flow field structures and pressure loss on staggered pin fin array in the wake region, where KV are dominate. These flow structures increase the local levels turbulence and generate eddies that promote flow …

Coupling Numerical Analysis Of Vibration And Thermal Buckling Of An Automotive Brake Disc, Joseph-Shaahu Shaahu

Electronic Theses and Dissertations

An engaged brake system generates high temperature gradients in the brake rotor and brake pads. This high temperature gradient in turn induces thermal buckling. During high speed rotation, vibration is likely to occur in the system. In terms of a brake disc vibration will occur when there is a misalignment of the brake disc or thermoelastic instability (hot spot) forms on the brake rotor. Coupled and uncoupled problems of thermal buckling and vibration of a brake disc are analyzed and presented using finite element analysis in this paper. Thermal buckling depends on the direction of the high temperature gradient. Having …

Empirical Evaluation Of Ground, Ceiling, And Wall Effect For Small-Scale Rotorcraft, Stephen Austin Conyers

Electronic Theses and Dissertations

Ground effect refers to the apparent increase in lift that an aircraft experiences when it flies close to the ground. For helicopters, this effect has been modeled since the 1950's based on the work of Cheeseman and Bennett, perhaps the most common method for predicting hover performance due to ground effect. This model, however, is based on assumptions that are often not realistic for small-scale rotorcraft because it was developed specifically for conventional helicopters. It is clear that the Cheeseman-Bennett model cannot be applied to today's multirotor UAVs. Experimental findings suggest that some of the conventional thinking surrounding helicopters cannot …