Digital Commons Network^™

Heat Transfer Analysis Of Two Pass Cooling Channel Of Gas Turbine Blade With Analytical Wall Function Turbulence Approach, Hitoshi Arakawa

Theses and Dissertations

This paper reports experimental and computational studies of heat transfer through a square duct with a sharp 180 degree turn. The main purpose of this research was to study heat transfer predictions using the Analytical Wall-Function (AWF). To compare the predicting performance of the AWF, the standard Log-Law Based Wall-Function (LWF) and a Low-Reynolds-number (LRN) k-e model were applied. Their results were also compared with experimental results for validation. In addition, three extended forms of the AWF were tested. The AWF showed better results than the conventional wall-function based on a logarithmic law especially in separation and reattachment regions and …

Real-Time Visualization Of Finite Element Models Using Surrogate Modeling Methods, Ryan C. Heap

Theses and Dissertations

Finite element analysis (FEA) software is used to obtain linear and non-linear solutions to one, two, and three-dimensional (3-D) geometric problems that will see a particular load and constraint case when put into service. Parametric FEA models are commonly used in iterative design processes in order to obtain an optimum model given a set of loads, constraints, objectives, and design parameters to vary. In some instances it is desirable for a designer to obtain some intuition about how changes in design parameters can affect the FEA solution of interest, before simply sending the model through the optimization loop. This could …

The Effect Of Cooling Rate Of Friction Stir Welded High Strength Low Alloy Steel, Scott Anthony Rose

Theses and Dissertations

The friction stir welding of steel has produced a hard zone in several different alloys. Despite its detrimental effects on weld toughness, the reasons behind neither its formation nor a method of reducing its size or effects have been explored. Recent advances in process control allow for direct heat input control, which combined with the use of backing plates of different thermal conductivity allows for an expansion of the process window. These control methods also affect the HAZ cooling rate by providing greater range (a 60% increase compared to a fixed backing plate) and control (five welds within 16 °C/s). …

Popup Height And The Dynamics Of Rising Buoyant Spheres, Randy H. Munns

Theses and Dissertations

In this paper the popup height of rising buoyant spheres is studied over a range of distinct release depths along with the accompanying velocities and accelerations near the free surface. In the past, regimes of motion due to vortex induced vibrations have been classified based on trajectories below the free surface. This study focuses on the popup height, velocity and acceleration at free surface exit, and vortex shedding in order to further define regimes of motion experienced by a rising buoyant sphere. Varying the release depth below the free surface reveals varying exit angles, velocities, accelerations, and popup heights at …

A Comparative Analysis Of Energy Modelingmethods For Commercial Buildings, Spencer Mark Salmon

Theses and Dissertations

This thesis researched the accuracy of measured energy data in comparison to estimated hand calculation data and estimated building energy performance simulation data. In the facility management industry, there is minimal evidence that building energy performance software is being used as a benchmark against measured energy usage within a building. Research was conducted to find examples of measured energy data compared to simulated data. The study examined the accuracy of a simulation software and hand calculations to measured energy data. Data suggests that comparisons may be made between building energy performance simulated data and measured data, though comparisons are solely …

The Sustainability Of Lean Manufacturing As A Competitive Advantage, Louis G. Jones

Theses and Dissertations

Since the early 1990s lean manufacturing has been employed by companies looking to reduce costs, increase efficiencies and improve quality. Academic studies of the financial benefits of lean manufacturing are mixed in their results, where some show benefit and others do not. The objective of the current work was to confirm a financial benefit of lean manufacturing, while also establishing whether such a financial advantage was sustainable. Financial data was collected for a large number of companies in the manufacturing sector, over the period from 1990 to 2010. The data were used to show correlation between inventory turns and return …

Variable Fidelity Optimization With Hardware-In-The-Loop For Flapping Flight, Michael Luke Duffield

Theses and Dissertations

Hardware-in-the-loop (HIL) modeling is a powerful way of modeling complicated systems. However, some hardware is expensive to use in terms of time or mechanical wear. In cases like these, optimizing using the hardware can be prohibitively expensive because of the number of calls to the hardware that are needed. Variable fidelity optimization can help overcome these problems. Variable fidelity optimization uses less expensive surrogates to optimize an expensive system while calling it fewer times. The surrogates are usually created from performing a design of experiments on the expensive model and fitting a surface to the results. However, some systems are …

The Water Entry Of Slender Axisymmetric Bodies: Forces, Trajectories And Acoustics, Kyle Gordon Bodily

Theses and Dissertations

Free surface water entry of various objects has been studied using high-speed images and image processing techniques for decades. This thesis studies the forces, velocities, and trajectories of slender axisymmetric projectiles using an embedded inertial measurement unit (IMU). Three nose shapes (cone, ogive, and flat) were used in the study. Additionally, the projectiles were tested at vertical and oblique impact angles with different surface conditions. One-half of each projectile was coated down the centerline with a hydrophobic spray, creating a half hydrophobic, half hydrophilic case. The trajectory of this half-and-half case impacting vertically was compared to the trajectory of symmetrically …

Dynamics And Control Of Wrist And Forearm Movements, Allan W. Peaden

Theses and Dissertations

Wrist and forearm motion is governed both by its dynamics and the control strategies employed by the neuromuscular system to execute goal oriented movement. Two experiments were conducted to increase our understanding of wrist and forearm motion. The first experiment involved 10 healthy subjects executing planned movements to targets involving all three degrees of freedom (DOF) of the wrist and forearm, namely wrist flexion-extension (FE), wrist radial-ulnar deviation, and forearm pronation-supination (PS). A model of wrist and forearm dynamics was developed, and the recorded movements were fed into the model to analyze the movement torques. This resulted in the following …

A Study Of Action Origami As Systems Of Spherical Mechanisms, Landen A. Bowen

Theses and Dissertations

Origami, the Japanese art of paper folding, has been used previously to inspire engineering solutions for compact, deployable designs. Action origami, the subset of origami dealing with models designed to move, is a previously unexplored area for engineering design solutions that are deployable and have additional motion in the deployed state. A literature review of origami in engineering is performed, resulting in seven key areas of technical origami literature from a wide variety of disciplines. Spherical mechanisms are identified as the method by which most action origami models achieve complicated motion while remaining flat-foldable. The subset of action origami whose …

Capillary Filling Of Large Aspect Ratio Channels With Varying Wall Spacing, Dallin B. Murray

Theses and Dissertations

Quantification and prediction of capillary fluid flow in planar nanochannels is essential to the development of many emerging nanofluidic technologies. Planar nanochannels are typically produced using the standard nanofabrication processes of thermal bonding or sacrificial etching. Both approaches may yield nanochannels that are bowed and/or exhibit non-uniform (i.e. non-planar) wall spacing. These variations in wall spacing affect the transient dynamics of a liquid plug filling the nanochannel, causing deviations from the classical behavior in a parallel-plate channel as described by the Washburn model. Non uniform wall spacing impacts the overall frictional resistance and influences the meniscus curvature. In this thesis, …

An Alternative System Identification Method For Friction Stir Processing, Dustin John Marshall

Theses and Dissertations

Temperature control has been implemented in friction stir processing and has demonstrated the ability to give improved process control. In order to have optimal control of the process, the parameters of the system to be controlled must be accurately identified. The system parameters change with tool geometry and materials, workpiece materials, and temperature. This thesis presents the use of the relay feedback test to determine the system parameters. The relay feedback test is easy to use and promotes system stability during its use. The results from the relay feedback test can be used to determine controller gains for a PID …

Fluid-Structure Interactions With Flexible And Rigid Bodies, David J. Daily

Theses and Dissertations

Fluid structure interactions occur to some extent in nearly every type of fluid flow. Understanding how structures interact with fluids and visa-versa is of vital importance in many engineering applications. The purpose of this research is to explore how fluids interact with flexible and rigid structures. A computational model was used to model the fluid structure interactions of vibrating synthetic vocal folds. The model simulated the coupling of the fluid and solid domains using a fluid-structure interface boundary condition. The fluid domain used a slightly compressible flow solver to allow for the possibility of acoustic coupling with the subglottal geometry …

A Multiobjective Optimization Method For Collaborative Products With Application To Engineering-Based Poverty Alleviation, Nicholas Scott Wasley

Theses and Dissertations

Collaborative products are created by combining components from two or more products to result in a new product that performs previously unattainable tasks. The resulting reduction in cost, weight, and size of a set of products needed to perform a set of functions makes collaborative products useful in the developing world. In this thesis, multiobjective optimization is used to design a set of products for optimal individual and collaborative performance. This is introduced through a nine step method which simultaneously optimizes multiple products both individually and collaboratively. The method searches through multiple complex design spaces while dealing with various trade-offs …

A Mathematical Model For Quantifying System Evolvability Using Excess And Modularity, Morgan Wesley Parry Tackett

Theses and Dissertations

An important factor in system longevity is service-phase evolvability, which is defined as the ability of a system to physically transform from one configuration to a more desirable configuration while in service. These transformations may or may not be known during the design process, and may or may not be reversible. A study of 210 engineered systems was performed and found that system excess and modularity allow a system to evolve while in service. Building on these observations, this thesis introduces mathematical relationships that map a system's excess and modularity to that system's ability to evolve. These relationships are derived …

Using Topology Optimization To Numerically Improve Barriers To Reverse Engineering, Devin Donald Lebaron

Theses and Dissertations

Here explored is a method by which designers can use the tool of topology optimization to numerically improve barriers to reverse engineering. Recently developed metrics, which characterize the time (T) to reverse engineer a product, enable this optimization. A key parameter use din the calculation of T is information content (K). The method presented in this thesis pursues traditional topology optimization objectives while simultaneously maximizing K, and thus T, in the resulting topology. This thesis presents new algorithms to 1) evaluate K for any topology, 2)increase K for a topology by manipulating macro-scale geometry and micro-scale crystallographic information for each …

An Exploration Of Carbon-Filled Carbon Nanotubes As A Potential Material In Coronary Stents, Kristopher Neil Jones

Theses and Dissertations

The purpose of this research is to explore the potential of using carbon-infiltrated carbon nanotubes (CI-CNT) as a material for coronary artery stents. Stents are commonly fabricated from metal, which may not perform as well as many polymers and ceramics in biomedical applications. Pyrolytic carbon, a ceramic, is currently used in medical implant devices due to its preferrable biocompatibility properties. Micro-patterned pyrolytic carbon devices can be created by growing carbon nanotubes, and then filling the space between with amorphous carbon via chemical vapor deposition. We prepared multiple samples of two different planar stent-like flexible geometries and smaller cubic structures out …

Mechanics Of Bolted Electrical Splices, Samuel Alberts

Theses and Dissertations

Localized heating of bolted electrical splices in the power distributing bus is a primary concern in the industrial automation industry. While localized heat generation problems are commonly reported in the field, it is not entirely clear what the root causes are. A methodology is presented for development of a tool to measure in-situ the influence of clamping load on the thermo-electric behavior of the splice joint. Applied research and reasoning used to identify probable root causes for failures reported in the field are also presented. Experiments were conducted to characterize the mechanical properties of the bolt and nut system used …

Development And Validation Of A Mathematical Model For Predicting The Performance Of Rotary Hammer Drills, Will Didier

Theses and Dissertations

Rotary hammer drills are specialized drills used by plumbers, electricians, and other construction trades to drill holes in concrete. This type of tool employs a mechanism driven by an electric motor to compress a column of air, generating an impact on a drill bit to break the concrete work piece. Rotary hammer development requires the ability to accurately predict tool performance to minimize the number of prototype iterations required during the design phase and ensure the tool delivers a satisfactory level of performance. In order to predict the performance of a rotary hammer drill, a mathematical model was developed to …

Investigation Of Some Self-Optimizing Control Problems For Net-Zero Energy Buildings, Xiao Li

Theses and Dissertations

Green buildings are sustainable buildings designed to be environmentally responsible and resource efficient. The Net-Zero Energy Building (NZEB) concept is anchored on two pillars: reducing the energy consumption and enhancing the local energy generation. In other words, efficient operation of the existing building equipment and efficient power generation of building integrated renewable energy sources are two important factors of NZEB development. The heating, ventilation and air conditioning (HVAC) systems are an important class of building equipment that is responsible for large portion of building energy usage, while the building integrated photovoltaic (BIPV) system is well received as the key technology …

Low Turbulence Wind Tunnel Design And Wind Turbine Wake Characterization, Andrew Welsh

Theses and Dissertations

As the prevalence of wind turbines in the energy market increases, so too does the demand for high-wind real-estate. As a result, wind turbines are placed closer together, which leads to structural challenges due to the cyclical fatigue loading from the wake of upwind turbines. Characterizing the wake behind wind turbines with respect to those downwind is especially important given the 20-year wind turbine lifetime that commercial wind turbine consumers expect. This project aimed to characterize the near wake behind a model wind turbine.

In order to accomplish this, a 12.8 meter-long and 1.22 meter-square test section low-turbulence wind tunnel …

A Vision-Based Relative Navigation Approach For Autonomous Multirotor Aircraft, Robert C. Leishman

Theses and Dissertations

Autonomous flight in unstructured, confined, and unknown GPS-denied environments is a challenging problem. Solutions could be tremendously beneficial for scenarios that require information about areas that are difficult to access and that present a great amount of risk. The goal of this research is to develop a new framework that enables improved solutions to this problem and to validate the approach with experiments using a hardware prototype. In Chapter 2 we examine the consequences and practical aspects of using an improved dynamic model for multirotor state estimation, using only IMU measurements. The improved model correctly explains the measurements available from …

Mimicking The Mechanical Behavior Of Advancing Disc Degeneration Through Needle Injections, Jeremy S. Alsup

Theses and Dissertations

Objective - To investigate the effects of injected protease solution on the mechanical advancement of disc degeneration, and to establish test protocol for future pre-clinical validation of spinal arthroplasty devices. The hypothesis that injection of a protease into a cadaveric lumbar disc will mimic advanced degeneration mechanics was the subject of this study. Summary of Background Information - Spinal disc degeneration is a universal condition that progresses in adults due to aging, disease, or injury. Stages of disc degeneration have been categorized in cadaver specimens, with each degeneration level exhibiting characteristic changes in flexibility parameters. Spinal disc tissue can be …

A Methodology For The Extraction Of Design Principles For Unfamiliar Markets, Robert D. Campbell

Theses and Dissertations

Successful product design focuses on design principles that are relevant to a target market. Consequently, the better these principles are understood and used, the higher the likelihood that resulting products will be well-received in that market. This thesis presents a method for extracting market-specific design principles for any market. The method employs user/designer-described characteristics of products within a market to extract the design principles specific to that market. The method generalizes the product characteristics, seeks to discover design decisions that could have resulted in those characteristics, and then extracts the underlying design principles. To demonstrate the ability of the method …

Fully Compliant Mechanisms For Bearing Subtraction In Robotics And Space Applications, Ezekiel G. Merriam

Theses and Dissertations

Robotics and space applications represent areas where compliant mechanisms can continue to make a significant impact by reducing costs and weight while improving performance. Because of the nature of these applications, a common need is for bearing replacement mechanisms, or mechanisms that perform the function of a bearing without the complexity and failure modes associated with bearings. Static balancing is a design strategy that attempts to reduce the actuation effort of a mechanism, and has been applied to compliant mechanisms in some applications. Monolithic construction, especially by means of 3D printing technology, is a strategy whereby the mechanism links and …

Investigations Of Partially Immersed Spinning Spheres In A Liquid Bath And Butterfly Flight, Kenneth Roy Langley

Theses and Dissertations

This thesis examines two important problems in fluid dynamics: that of a partially immersed sphere spinning in a bath of liquid and the measurement of flow velocities around a free flying butterfly. Although the actual problems are quite different, each problem incorporates many of the same principles and techniques. When a hard-boiled egg spins through a pool of milk on the kitchen counter, the milk rises up the sides of the egg and droplets are ejected. This phenomenon occurs when any partially submerged object whose radius increases upward from the fluid surface (e.g., spheres, inverted cones, rings, etc.), spins in …

Passive Stiffness Of Coupled Wrist And Forearm Rotations, Will Brandon Drake

Theses and Dissertations

The dynamics of wrist rotations are dominated by joint stiffness, which the neuromuscular system must account and compensate for when controlling wrist movements. Because wrist stiffness is anisotropic, movements in some directions require less torque than movements in others, creating opportunities to follow "paths of least resistance." Forearm pronation-supination (PS) can combine with wrist flexion-extension (FE) and radial-ulnar deviation (RUD) to allow the wrist to rotate in directions of least stiffness. Evaluating this hypothesis, and understanding the control of combined wrist and forearm rotations in general, requires a knowledge of the stiffness (the dominant mechanical impedance) encountered during combined wrist …

Starch Resin Moisture Level Effect On Injection Molding Processability And Molded Part Mechanical Properties With Pure Starch Resin And Polymer Blends, Jordan M. Ellingson

Theses and Dissertations

The current and forecasted global consumption of plastic packaging and products through the 21st century combined with the already reported and growing negative impact of plastics on the environment due to plastics being synthesized from nonrenewable resources that do not biodegrade is of serious concern. However, recent advances in starch technology including the development of thermoplastic starch (TPS) materials —polymers that are both renewable and biodegradable—have brought hope to reducing this impact. The mechanical properties of thermoplastic starch have often been improved by blending with synthetic polymers. One issue that arises with blending is volatilization of the melt from moisture …

Location-Allocation Optimization Of Supply Chain Distribution Networks: A Case Study, Mark Nicholas Helberg

Theses and Dissertations

The location of distribution centers is an important strategic decision in supply chain design, particularly as it relates to service quality, productivity, and profitability of the firm. There has been extensive research performed on distribution location models which require the use of complex algorithms and assumptions that make use of these models difficult in practice for small and medium enterprises (SMEs) that have limited capital and resources. Studies have also failed to capture and quantify potential business results of using more sophisticated methods. In this study, a deterministic and static location-allocation model is designed using a prototype software tool. The …

Design And Testing Of An H2/O2 Predetonator For A Simulated Rotating Detonation Engine Channel, Stephen J. Miller

Theses and Dissertations

A study is presented on the relationship between a pre-detonator and a detonation channel of an RDE. Testing was conducted on a straight narrow channel made of clear polycarbonate windows connected to an H2/O2 pre-detonator to simulate the RDE initiation scheme and allow for flow visualization. A comparison is made on decoupling distance and wave velocities for a range of pre-detonator designs, inclination angles, equivalence ratios and geometries placed within the simulated channel. Regardless of inclination angle or equivalence ratio the detonation wave decoupled within 25 mm from the pre-detonator exit into the channel. A step change in diameter 25 …