Mechanical Engineering Commons^™

A Parametric Study On Power Variation For Model Wind Turbine Arrays, Dominic Delucia

Dissertations and Theses

This thesis presents the results of wind tunnel experiments performed for various model wind turbine arrays. The aim is to understand how siting affects power output. To optimize wind farm efficiency the experiments vary the parameters of the model wind turbines and the layout of the wind turbine array. The parameters include the alignment, height, spacing, and the rotational direction of the model wind turbines. These experiments employ mechanical torque sensors to simultaneously measure the torque and rotor angular velocity, which yields a direct measurement of the fluid mechanical power extracted by the turbine at multiple locations. For a 4 …

Thermal Transport To Sessile Water Droplets On Heated Superhydrophobic Surfaces Of Varying Cavity Fraction, Robb C. Hays

Theses and Dissertations

The hydrophobicity of a surface is defined as the degree to which it repels water molecules, and the internal contact angle that the droplet makes with the surface is a measure of the hydrophobicity. Contact angles less than 90° occur on hydrophilic surfaces, while contact angles greater than 90° occur on hydrophobic surfaces. If a surface's contact angle is greater than 120° the surface is commonly defined as superhydrophobic (SH). Superhydrophobicity is accomplished through a combination of microscale surface roughness and water repellant surface chemistry. The roughness creates cavities, or pockets, of vapor underneath the droplet which act to increase …

Identification Of Markov Processes Within A Wind Turbine Array Boundary Layer, Matthew Scott Melius

Dissertations and Theses

The Markovianity within a wind turbine array boundary layer is explored for data taken in a wind tunnel containing a model wind turbine array. A stochastic analysis of the data is carried out using Markov chain theory. The data were obtained via hot-wire anemometry thus providing point velocity statistics. The theory of Markovian processes is applied to obtain a statistical description of longitudinal velocity increments inside the turbine wake using conditional probability density functions. It is found that two and three point conditional probability density functions are similar for scale differences larger than the Taylor micro-scale. This result is quantified …

Analysis Of Prosthetic Leg Shock Absorption And Structure, Russell Dibb, David Williams, Dr. Mark Colton

Journal of Undergraduate Research

The purpose of the prosthetic leg project was to research and design a below-the-knee prosthetic leg that could be used in developing countries. Many prosthetic legs that are currently on the market are very expensive and difficult to manufacture in undeveloped areas of the world. The engineering challenges that the prosthetic leg design addressed include a device that is 1) capable of being manufactured at a low cost ($100-$500), 2) simply and easily reproducible in a developing country, 3) durable enough to hold up to the vigorous conditions that exist in a developing country, and 4) able to effectively modeling …

Parametric Human Spine Model, Simeon Smith, Dr. Anton Bowden

Journal of Undergraduate Research

Three-dimensional computer models are commonly used to understand and analyze pathological conditions of the spine. Models of the spine are most beneficial when they match each patient’s spinal geometry. Currently, making a model for a specific patient is a long, multi-step process that must be started anew for each person. The goal of this project was to create a parametric model that can be used to instantly generate the spinal geometry of any particular patient based on the input of a few controlling parameters.

Development Of A Simple Manufacturing Process For A Prosthetic Leg, Kyle Smith, Dr. Mark Colton

Journal of Undergraduate Research

The purpose of this project was to develop a simple process to manufacture a useful and affordable prosthetic leg to be made available to below-the-knee amputees in a sub-Saharan African country. This project was motivated by a desire for learning and experience and also by humanitarian and social entrepreneurship ideals. The project was carried out as a joint effort by a larger research team composed of members of the BYU Biomedical Engineering Club. As this was a joint team effort, many of the tasks detailed in this report were shared between several team members. Currently, the team has identified partners …

Sustainable Bulding Materials In Mozambique, Jared Geddes, Dr. Robert Todd

Journal of Undergraduate Research

The research that I conducted this year was in the area of sustainable building materials. I worked with a team of six engineers to develop a sustainable building material that would be able to withstand the heavy monsoon rains common to the area of Beira, Mozambique. Every year, these rains destroy up to 60% of the local buildings, consisting mainly of local residences made from mud, straw, and sticks. This destruction and the resultant flooding causes an unsafe and unsanitary condition for the local residents. One of the most dangerous aspects of this flooding is the problem of the sanitation. …

Development Of A Simple Manufacturing Process For A Prosthetic Leg, John Christiansen, Dr. Mark Colton

Journal of Undergraduate Research

The purpose of this project was to develop a simple process to manufacture a useful and affordable prosthetic leg to be made available to below-­‐the-­‐knee amputees in a sub-­‐ Saharan African country. This project was motivated by a desire for learning and experience and also by humanitarian and social entrepreneurship ideals. The project was carried out as a joint effort by a larger research team composed of members of the BYU Biomedical Engineering Club. As this was a joint team effort, many of the tasks detailed in this report were shared between several team members. Currently, the team has identified …

Prosthetic Leg Project, Carl Ellingson

Journal of Undergraduate Research

The idea of this project was to research prosthetic leg designs in an effort to create a below-the-knee prosthetic device. The goal was to come up with a device that could be used in third world countries where the need is most considerable. In the past year we have come up with a design and are still in the process of testing the leg. We did not finish as fast as we would have liked, and we are still working on additional testing before we can present our idea to the scholarly community.

Pace Global Collaboration Race Car Project And Pace Emerging Market Engine Project, Jesse Davis, Dr. C. Greg Jensen

Journal of Undergraduate Research

I have been involved with Partners for the Advancement of Collaborative Engineering Education (PACE) since January 2008. The goal of this organization involving industry sponsors and student teams is to teach and foster engineering collaboration in today’s global market. Various projects are undertaken in PACE, but the main focus is design and engineering in the automotive field. I participated in two projects during the past year.

Analysis Of Prosthetic Leg Shock Absorption And Structure, David Williams, Russell Dibb, Dr. Mark Colton

Journal of Undergraduate Research

The purpose of the prosthetic leg project was to research and design a below-the-knee prosthetic leg that could be used in developing countries. Many prosthetic legs that are currently on the market are very expensive and difficult to manufacture in undeveloped areas of the world. The engineering challenges that the prosthetic leg design addressed include a device that is 1) capable of being manufactured at a low cost ($100-$500), 2) simply and easily reproducible in a developing country, 3) durable enough to hold up to the vigorous conditions that exist in a developing country, and 4) able to effectively modeling …

Mechanical Characterization Of Accelerated Human Lumbar Disc Degeneration, John Sessions, Dr. Anton Bowden

Journal of Undergraduate Research

It is reported by the American Academy of Orthopeadic Surgeons that in 2005, 24% of the population sought treatment for back pain [1]. Additionally, Americans spent over $85.9 billion (2005) on health treatment costs related to back problems with the vast majority being connected to disc degeneration [1]. Despite the vast sum of money being spent on treatment of disc degeneration, the leading surgical treatments for disc degeneration (spinal fusion, total disc replacement) have been shown to increase degeneration at the discs in adjacent levels to the surgery [2].

High-Speed, Three-Dimensional Quantification Of Ladybug (Hippodamia Convergens) Flapping Wing Kinematics During Takeoff, Ryan B. George, Dr. Scott L. Thomson

Journal of Undergraduate Research

Ladybug wing and body kinematics during takeoff is explored using high-speed stereoscopic imaging. Recordings of the specimens during flight are acquired at a rate of 3000 frames per second. A direct linear transformation algorithm is performed using custom implementation in Matlab to quantify positions of selected locations on the body, forewings (elytra), and hindwings. Design and setup of instrumentation and analysis procedures are explained. Flapping frequency is reported. Significant motion of the elytra and other findings are presented and their applications are discussed.

Transtibial Suspension, Peter Jepsen, Dr. Anton Bowden

Journal of Undergraduate Research

Amputees in developing countries struggle to find employment because of their disabilities, but also struggle to afford the artificial limbs that are available to them. Further compounding the problem is the lack of comfortable fitting prosthetics, which are hard to find and design even in advanced nations. I researched, designed and tested suspension systems that could be made for a transtibial (below the knee) prosthetic leg that would be both comfortable and inexpensive.

Optimizing Cvt Performance For A Sae Mini-Baja Application, Jisang Sun, Dr. Robert H. Todd

Journal of Undergraduate Research

The Continuously Variable Transmission (CVT) is a mechanical device that transfers power from an engine to another device such as a gear box or reducer. It mainly consists of three major parts; a speed sensitive drive pulley, a torque sensitive driven pulley and a V-belt. A CVT has the ability to adjust the gear ratio between the engine and the gear box automatically based on engine RPM and the torque needed to drive the driven pulley. CVT’s are widely used in special purpose vehicles such as all terrain vehicles (ATV’s) and snowmobiles. CVT’s are also used for the national Mini-Baja …

Mathematical Model Of Friction Stir Welding, Jeremy D. Webb, Dr. Russell Daines

Journal of Undergraduate Research

Friction Stir Welding (FSW) is a semi-solid state joining process. The process utilizes a threaded pin tool “stirring” two aluminum plates together as it “sews” the seam together. One application of this process would replace the use of rivets to join aluminum paneling on commercial aircraft.

Analysis Of A Compliant Centrifugal Clutch Using Computeraided Engineering Tools, James D. Baker, Dr. Larry L. Howell

Journal of Undergraduate Research

Contemporary engineering has received the benefits of computer-aided engineering (CAE) tools that automate and simplify the design of mechanical systems. However, such tools do not provide direct support for the specific field of compliant mechanisms, whose behavior can require difficult techniques for design and synthesis. Compliant mechanisms utilize flexible segments instead of joints, to achieve their motion. It was proposed that two CAE tools, namely Pro/ENGINEER and ADAMS/View, along with a method for analyzing compliant mechanisms known as the pseudo-rigid-body model, could greatly reduce the time and effort required to generate accurate results in the analysis of a compliant centrifugal …

The Design And Synthesis Of A Compliant Bicycle Derailer, Matthew Christensen, Dr. Larry L. Howell

Journal of Undergraduate Research

Compliant mechanisms are those which gain part or all of their motion from the flexibility of their parts. For example, the motion of a hinge can be alternatively provided by a pin (like a hinge on a door), or by a thin flexible member (like a hinge in the cover of a book). The door hinge is easily designed by selecting brackets and a pin with adequate strength to support the loads. The book hinge is more difficult to design. The book has additional considerations like designing the material thin enough to bend, thick enough to bear the load, and …

Small Uavs For Perch And Stare Missions: Ground Locomotion And Self-Launch, Stephen Carlson, Dr. Jerry Bowman

Journal of Undergraduate Research

The mission of this project was the development of an Unmanned Air Vehicle capable of complete autonomy in a terrestrial environment. Using a jumping system for zero-distance take-offs and the addition of ground locomotion devices and energy harvesting systems, the vehicle could operate indefinitely without human assistance. Although this aircraft is unfinished, it and later design attempts have been tested to satisfy the basic fundamentals of this mission. The project will be continued until the stated mission objectives are achieved.

The Development And Refinement Of Constant-Force Mechanisms For Use In Future Applications, Brent L. Weight, Dr. Larry L. Howell

Journal of Undergraduate Research

A compliant mechanism is one in which the mechanism’s motion comes from deflection of one or more of its members. Compliant mechanisms offer several advantages over rigid-body mechanisms. The member deflection characteristic of compliant mechanisms results in the ability to store energy directly within the member, eliminating the need for additional energy storage devices (i.e. springs) found in rigid-body mechanisms. The member deflection also allows for the replacement of pin joints with small length flexural pivots, or living hinges, thereby reducing part count and assembly time. In fact, one of the most significant advantages of compliant mechanisms is their ability …

Freeze-Thaw Effect On Mechanical Properties Of Bovine Ligaments, Alan Bordon, Dr. Anton Bowden

Journal of Undergraduate Research

My ORCA grant proposal was to study the effect that freezing and thawing a soft tissue has on the results of the mechanical property tests (i.e how strong) performed on the tissue. I was to study the effect of a single and multiple freeze/thaw cycles on the tissue. My hypothesis was that there was a deleterious effect and this was important to account for when doing testing with soft tissue.

Flow-Induced Crystallization Of Isotactic Polypropylene And Random Polyethylene–Polypropylene Copolymers, Frederic Aubin

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Flow-induced crystallization (FIC) has been investigated for decades but the effect of molecular characteristics that hinder crystallization—such as the presence of random comonomers— on FIC remains scarcely explored. Flow greatly enhances crystallization kinetics and can induce the formation of highly oriented morphologies that affect final properties (i.e. stiffness, permeability, thermal conductivity, elastic modulus, etc.). Therefore, understanding FIC remains particularly important for developing predictive models to allow optimization of processing techniques involving flows.

Polypropylene represents ~ 40% of the global polyolefin production. The addition of ethylene comonomer allows their use as engineering plastics because of their particular toughness and flexibility. This …

The Determination Of Grain Boundary Structure, Ryan J. Larsen, Dr. Brent L. Adams

Journal of Undergraduate Research

A growing focus of material science research is relating material properties to grain boundary geometry. The purpose of my research has been to improve current methods of determining grain boundary geometry and to relate interface geometry to sensitization of AISI type 304 stainless steel. Sensitization is the formation of chromium carbides that occurs in a temperature range of 500-800 °C, and makes the material more susceptible to intergranular stress corrosion cracking and stress corrosion cracking.

The Effect Of The Duct Area To Rocket Area Ratio And Rocket Expansion On Ejector-Rocket Performance, Michael I. Kellogg, Dr. Russell Daines

Journal of Undergraduate Research

Space is the final frontier. That has been generally believed since Sputnik went up in the 1950’s, but in spite of this optimistic belief, homesteaders have not yet begun to settle Mars, nor have businesses sponsored ventures to other planets. One of the reasons that the final frontier is so quiet is the prohibitive expense of getting there. Currently it cost about $10,000 to launch a pound of payload into low earth orbit.1 NASA, in an effort to lower the cost of launching payloads into space, has been encouraging researchers to develop alternative launch vehicles to replace the Space Shuttle. …

Particle Morphology And Elemental Composition Of Heavy Fuel Oil Ash At Varying Atomization Pressures, Daniel Abraham Tovar

Theses and Dissertations

Land-based turbine engines are currently used to burn heavy fuel oil (HFO), which is a lower cost fuel. HFO contains inorganic material that forms deposits on turbine blades reducing output and efficiency. Magnesium based additives are used to inhibit vanadium pentoxide deposition and reduce the corrosive nature of the gas and deposits in the hot gas path of the gas turbine. The focus of this study was to determine particle morphology and elemental composition of ash when firing HFO in an atmospheric combustor at various fuel injector atomization pressures. Prior to firing, the HFO was washed with water to remove …

Examination Of Material Flow Characteristics In Friction Stir Welding, S. James Felsted, Dr. Tracey W. Nelson

Journal of Undergraduate Research

Friction Stir Welding is a solid state joining process that makes possible the joining of materials that were previously difficult or impossible to weld. A closer examination of friction stir welding shows that welding occurs because of mechanical mixing, frictional heating, and forging. Welds are made on a conventional milling machine that powers a steel tool consisting of a shank, shoulder, and pin (1). This process is being investigated in order to better understand the interaction of the tool with the material and the nature of the material deformation.

The Mechanics Of Intracranial Loading During Blast And Blunt Impacts: Experimental And Numerical Studies, Veera Selvan Kuppuswamy

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Head injuries in an explosion occur as a result of a sudden pressure changes (e.g. shock-blast) in the atmosphere (primary injury), high velocity impacts of debris (secondary injury) and people being thrown against the solid objects (tertiary injury) in the field. In this thesis, experimental and numerical approaches are used to delineate the intracranial loading mechanics of both primary (blast) and tertiary injuries (blunt).

The blast induced head injuries are simulated using a fluid-filled cylinder. This simplified model represents the head-brain complex and the model is subjected to a blast with the Friedlander waveform type of loading. We measured the …

Cyclic Durability Of A Solid Oxide Fe-Air Redox Battery Operated At 650°C, Xuan Zhao, Yunhui Gong, Xue Li, Nansheng Xu, Kevin Huang

Faculty Publications

The recently developed rechargeable solid oxide metal-air redox battery has shown a great potential for applications in mid- to large-scale stationary energy storage. Cyclic durability is one of the most important requirements for stationary energy storage. In this study, we report the cyclic durability of a solid oxide Fe-air redox battery operated at 650◦C. The battery was continuously cycled 100 times under a current density of 50 mA/cm2 with rather flat performance, producing an average specific energy of 760 Wh/kg-Fe at a round-trip efficiency of 55.5%. The post-test examination indicated that the performance losses could arise from the fuel-electrode of …

Cyclic Durability Of A Solid Oxide Fe-Air Redox Battery Operated At 650°C, Xuan Zhao, Yunhui Gong, Xue Li, Nansheng Xu, Kevin Huang

Faculty Publications

The recently developed rechargeable solid oxide metal-air redox battery has shown a great potential for applications in mid- to large-scale stationary energy storage. Cyclic durability is one of the most important requirements for stationary energy storage. In this study, we report the cyclic durability of a solid oxide Fe-air redox battery operated at 650°C. The battery was continuously cycled 100 times under a current density of 50 mA/cm² with rather flat performance, producing an average specific energy of 760 Wh/kg-Fe at a round-trip efficiency of 55.5%. The post-test examination indicated that the performance losses could arise from the fuel-electrode …

Model Reference Robust Control For Marine Propulsion Systems With Model Uncertainty Caused By Hull Deformation, Zhixiong Li, Xinping Yan, Li Qin, Chengqing Yuan, Zhongxiao Peng

Journal of Marine Science and Technology–Taiwan

A marine propulsion system can be strongly coupled with the hull deformation in a large-scale ship. The interaction of this coupling dynamics increases the nonlinearity and complexity of the control model. Traditional control method based on the empirical PID (proportion-integration-differentiation) parameters has difficulty in dealing with the model uncertainty caused by the hull deflection. However, up to date, limited work has been done to address the model uncertainty problem of the marine propulsion system. It is therefore imperative to develop feasible and effective control systems that take the model uncertainty into account. In this study, a new method based on …