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Articles 631 - 660 of 1342
Full-Text Articles in Mechanical Engineering
Optimizing Cvt Performance For A Sae Mini-Baja Application, Jisang Sun, Dr. Robert H. Todd
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
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
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
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
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
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
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.
The Determination Of Grain Boundary Structure, Ryan J. Larsen, Dr. Brent L. Adams
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
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
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
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.
Analysis Of Intervertebral Disc Degeneration Testing Method, David Williams, Dr. Anton Bowden
Analysis Of Intervertebral Disc Degeneration Testing Method, David Williams, Dr. Anton Bowden
Journal of Undergraduate Research
This ORCA research project has focused on the determination of the effects of the order of the mechanical tests on the response of an intervertebral disc. We hypothesized that the order of the mechanical tests may influence the rate of diffusion of the Trypsin throughout the disc, affecting the biomechanical response. We have planned to determine the magnitude of this influence by using statistical techniques to analyze the data acquired. Virtually all of us (80 to 90 percent) will experience back pain in our lives. Low back pain is the leading cause of missed work days. The estimated economic impact …
Influence Of Airway Liquid Hydration And Properties On Human Vocal Fold Vibration, Preston Murray, Dr. Scott Thomson
Influence Of Airway Liquid Hydration And Properties On Human Vocal Fold Vibration, Preston Murray, Dr. Scott Thomson
Journal of Undergraduate Research
The purpose of this research project was to identify a fluid that has similar properties as the airway surface liquid (ASL) that covers vocal folds, and then apply it to a vibrating synthetic vocal fold model to measure its effects.
Parametric Optimization Of Wind Turbine Blades, Brycee Mcewen, Dr. Steven Gorrell
Parametric Optimization Of Wind Turbine Blades, Brycee Mcewen, Dr. Steven Gorrell
Journal of Undergraduate Research
With ever increasing concerns about the production of greenhouse gases from burning fossil fuels, more and more emphasis is being placed on researching and developing alternative and renewable energy resources. One renewable energy source that has the potential to compete with conventional fossil fuels, is wind energy. In order for wind energy to be competitive, it is necessary to make improvements in both aerodynamic and structural properties of wind turbines.
Piezoresistivity In Nickel Nanostrand Composite Materials As Studied By Three-Dimensional Reconstruction On Focused Ion Beam Serial-Sections, Oliver Johnson, Dr. David Fullwood
Piezoresistivity In Nickel Nanostrand Composite Materials As Studied By Three-Dimensional Reconstruction On Focused Ion Beam Serial-Sections, Oliver Johnson, Dr. David Fullwood
Journal of Undergraduate Research
The development of a large-strain sensor technology will open doors for improved engineering design and scientific research in many fields. Such a technology would allow for advances in biomechanical engineering, e.g., prosthetic limb and artificial organ design. Additionally this kind of sensor technology could be used for tactile robotics and even structural health monitoring, such as in wind turbines or architectural structures. Our research group has developed a unique Silicone/Nickel Nanostrand/Nickel Coated Carbon Fiber (Si/NiNs/NCCF) nanocomposite that can measure strains of up to 50% elongation. The purpose of this project was to investigate how the nano-scale structure of this material …
Autonomous Soaring Using Real-Time Wind Estimation, Mark J. Cutler, Dr. Timothy Mclain
Autonomous Soaring Using Real-Time Wind Estimation, Mark J. Cutler, Dr. Timothy Mclain
Journal of Undergraduate Research
Small unmanned aerial vehicles (UAVs) are obtaining increasing utilization in many applications. Their small size (0.5-4m wingspan) allows them to fly close to the ground, providing useful observation and tracking data. This small size, however, comes at the expense of flight time. As UAV size decreases, the amount of stored energy (electrical or chemical) the UAV is able to carry also decreases. If long flight times are to be obtained with a small UAV, other energy sources must be exploited. Naturally occurring atmospheric phenomena provide one such potential energy source.
Dynamic Loading On Horizontal Axis Wind Turbine Blades, Christopher Brinkerhoff, Julie Vanderhoff
Dynamic Loading On Horizontal Axis Wind Turbine Blades, Christopher Brinkerhoff, Julie Vanderhoff
Journal of Undergraduate Research
Currently, there is much interest involving technologies dealing with clean and renewable energy sources. The current goal in the United States is to produce 20% of its electrical needs by wind power by the year 2030. Wind energy is seen as a viable option for further research because of its low carbon footprint and virtually limitless supply of wind, but in order for it to be economically viable, there are certain aspects of wind technology that need improvement.
Economic And Environmental Justification Of A Thermoelectric Waste Heat Recovery System, John Christiansen, Dr. Matthew Jones
Economic And Environmental Justification Of A Thermoelectric Waste Heat Recovery System, John Christiansen, Dr. Matthew Jones
Journal of Undergraduate Research
In recent years, the concepts of energy, energy production, effects of energy consumption on the environment, and sustainable development have become increasingly significant as members of society become more aware of their level of energy consumption. However, in energy production for home, commercial, or industrial use, up to 60 percent of the chemical energy potential (in the form of fossil or other fuels) is lost in the form of waste heat. In other words, when fossil or other fuels are burned, only 30 to 40 percent of the potential chemical energy is actually harnessed and converted into useful electricity! This …
Vision-Based Guidance For Air-To-Air Tracking And Rendezvous Of Unmanned Aircraft Systems, Joseph Walter Nichols
Vision-Based Guidance For Air-To-Air Tracking And Rendezvous Of Unmanned Aircraft Systems, Joseph Walter Nichols
Theses and Dissertations
This dissertation develops the visual pursuit method for air-to-air tracking and rendezvous of unmanned aircraft systems. It also shows the development of vector-field and proportional-integral methods for controlling UAS flight in formation with other aircraft. The visual pursuit method is a nonlinear guidance method that uses vision-based line of sight angles as inputs to the algorithm that produces pitch rate, bank angle and airspeed commands for the autopilot to use in aircraft control. The method is shown to be convergent about the center of the camera image frame and to be stable in the sense of Lyapunov. In the lateral …
Development/Ballistics Testing Of Lightweight Sandwich-Composite Body Armor, Brian Spencer, Dr. Anton Bowden
Development/Ballistics Testing Of Lightweight Sandwich-Composite Body Armor, Brian Spencer, Dr. Anton Bowden
Journal of Undergraduate Research
Body armor is one of the most important tools used in the protection of soldiers and other armed forces around the world. Although the current style of armor, using Kevlar fiber and ceramic inserts, is generally effective, it is bulky and heavy and can cause overheating and lack of mobility. Our research attempts to remedy these issues by using shear-thickening fluid (STF) impregnated Kevlar XP combined with corrugated plastic to create and test lighter, more effective body armor.
Critical Component Selection For Implementing Barriers To Reverse Engineering, Shane K. Curtis, Dr. Christopher Mattson
Critical Component Selection For Implementing Barriers To Reverse Engineering, Shane K. Curtis, Dr. Christopher Mattson
Journal of Undergraduate Research
Reverse engineering is a prominent design strategy in industry, employed by many to uncover the enabling technologies of innovative products. Unfortunately, there is little motivation for original designers to create new products if competitors can reverse engineer these products and reproduce them at a lower development cost. One solution to this problem involves the incorporation of barriers to reverse engineering into products during the design process. These barriers not only increase the cost of reverse engineering but can also improve product performance with only a small increase in manufacturing or development time.
Development Of A Sense And Avoid System For Small Unmanned Aircraft Systems, Robert Andrew Klaus
Development Of A Sense And Avoid System For Small Unmanned Aircraft Systems, Robert Andrew Klaus
Theses and Dissertations
Unmanned aircraft systems (UAS) represent the future of modern aviation. Over the past 10 years their use abroad by the military has become commonplace for surveillance and combat. Unfortunately, their use at home has been far more restrictive. Due to safety and regulatory concerns, UAS are prohibited from flying in the National Airspace System without special authorization from the FAA. One main reason for this is the lack of an on-board pilot to "see and avoid" other air traffic and thereby maintain the safety of the skies. Development of a comparable capability, known as "Sense and Avoid" (SAA), has therefore …
Real-Time Visualization Of Finite Element Models Using Surrogate Modeling Methods, Ryan C. Heap
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 …
Non-Redundant Sensor Fault Detection Using An Improved Dynamic Model, Brandon Cannon, Robert C. Leishman, Timothy W. Mclain, Joseph Jackson, Jovan Boskovic
Non-Redundant Sensor Fault Detection Using An Improved Dynamic Model, Brandon Cannon, Robert C. Leishman, Timothy W. Mclain, Joseph Jackson, Jovan Boskovic
Faculty Publications
This paper proposes a method of detecting faults in non-redundant sensors. Such a method is advantageous for small unmanned aerial vehicles (UAVs), which are prevented from carrying redundant sensors due to size, weight, and power constraints. The method we propose uses a multiplicative extended Kalman lter (MEKF) for estimation and employs hypothesis testing to detect faults. This method has been shown to detect bias, drift, and increased noise in a non-redundant sensor real-time on board an autonomous rotorcraft.
Robust Motion Estimation With Rgb-D Cameras, Robert C. Leishman, Daniel Koch, Timothy W. Mclain
Robust Motion Estimation With Rgb-D Cameras, Robert C. Leishman, Daniel Koch, Timothy W. Mclain
Faculty Publications
Estimating vehicle motion using vision sensors in real time has been greatly explored in the past few years due to speed improvements and advances in computer hardware. Six degree of freedom motion estimation using vision information is desirable due to a vision sensors low cost, low power requirements and light weight and for the quality of the solutions that can be obtained using few assumptions about the environment. However, cameras have the downside of not providing good estimates when visual features are sparse or not available. Also, there are problems with changes in lighting and when light is low or …
The Effect Of Cooling Rate Of Friction Stir Welded High Strength Low Alloy Steel, Scott Anthony Rose
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
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
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 …
Variable Fidelity Optimization With Hardware-In-The-Loop For Flapping Flight, Michael Luke Duffield
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 Sustainability Of Lean Manufacturing As A Competitive Advantage, Louis G. Jones
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 …