Mechanical Engineering Commons^™

Calibration And Optimization Of A Load Sensor Embedded In A Railroad Bearing Adapter, Lorenzo Saenz Iv

Theses and Dissertations - UTB/UTPA

Freight railcars rely heavily on weigh bridges and stations to determine cargo load. As a consequence, all load measurements are limited to certain locations and specified prices. To this end, this study presents work performed to develop one of the first economical, reliable sensors for keeping track of both dynamic and static loads on a freight railcar. Preliminary testing provided a strain-gauge based sensor that delivered load information in the laboratory environment. Federal Railroad Association (FRA) protocol testing was met and consistent results were obtained from the sensing device. The latter allowed for an optimized sensor that could potentially deliver …

Proper Orthogonal Decomposition Of High-Speed Flows, Oscar Huerta

Theses and Dissertations - UTB/UTPA

In an effort to understand physical characteristics of high speed flows such as an Impinging Jet (Mach 1.5) and Pulsed Jet (Mach 0.3) both propulsions systems are investigated from phased-locked Particle Image Velocimetry (PIV) data that is analyzed using Proper Orthogonal Decomposition (POD). The purpose of POD is to extract the most dominant features found in the flow. The method calculates the eigenvalues and the spatial eigenfunctions that are related to the total kinetic energy with only a few basis functions. Results for an Impinging Jet show about 70% of the energy in the first twenty modes that represent the …

Towed Water Turbine Computational Fluid Dynamics Analysis, Robert G. Maughan

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Computational fluid dynamics can be used to predict operating conditions of towed water turbines which are used in long distance sailing applications to meet electrical demands. The design consists of a turbine fastened to a shaft which is attached to a generator by a rope. The turbine is pulled in water behind a sailboat and torque is transmitted through the rope to turn the onboard generator and produce power. Torque curves from an alternator, generator, and from computational fluid dynamics were used to determine the operating spin rate and output power of the system. On-water tests were conducted to determine …

Miniature Wire Boom System For Cubsat Application, Keith R. Bradford

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Small satellites and especially CubeSats are becoming more widely used to study the space environment. The Ionosphere is one region of particular interest, more specifically the altitude region of 85 km to 600 km. Small satellites are particularly useful for studying this region of the Earth’s atmosphere since the effects of aerodynamic drag on a CubeSat are much less than those on a larger more traditional satellite, thus the lifespan of a CubeSat in this region is much longer. In order to observe the electric field in space, the electric potential between various points needs to be measured. These measurements …

Closed Loop Control Of A Cylindrical Tube Type Ionic Polymer Metal Composite (Ipmc), Benjamin Mead

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this research is to provide a framework for the integration of tube type, cylindrical Ionic Polymer Metal-Composite (IPMC) into conventional devices. IPMCs are one of the most widely used types of electro-active polymer actuator, due to their low electric driving potential and large deformation range. For this research a tube type IPMC was investigated. This IPMC has a circular cross section with four separate electrodes on its surface and a hole through the middle. The four electrodes allow for biaxial bending and accurate control of the tip location. One of the main advantages of using this type …

Investigation Of Peak Load Reduction Strategies In Residential Buildings In Cooling Dominated Climates, Fady Atallah

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation of peak load reduction strategies in residential buildings contributes to the global international efforts in reducing energy consumption and is related directly to energy efficiency in residential and commercial buildings. Work reported here involves computer aided building energy simulation of energy efficient and non-energy efficient residential homes coupled with empirical energy consumption data gathered from monitoring an array of energy efficient residential homes. The latter have been implemented for peak load reduction strategies. In addition non-energy efficient residential homes have been monitored to compare performance to the energy efficient homes. This study demonstrates the crucial importance of energy …

Consequences Of Four-Point, Strap-Type Wheelchair Tiedown And Occupant Restraint System Practices On Wheelchair Passenger Safety In Fixed-Route Transit., Zdravko Salipur

Electronic Theses and Dissertations

Many wheelchair users rely upon fixed route public transportation using large accessible transit vehicles (LATVs) for independent transportation to and from work, healthcare appointments and leisure activities. A substantial number of these wheelchair users may not be able to transfer from their wheelchair to a motor vehicle seat during transit. It is necessary to afford these wheelchair users the same level of safety as occupants seated in motor vehicle seats. Therefore, the Americans with Disabilities Act (ADA) requires that LATVs be equipped with wheelchair securement and occupant restraint systems (WTORS). The four-point tiedowns and occupant restraints are the primary means …

Supersonic Turbine Cascade Studies Using Computational Fluid Dynamics And Water Table Experiments, Shelby E. Nelson

Honors College Theses

Design engineers use a variety of tools to perform calculations and to aid in the design process. For example, engineers designing gas turbines, specifically the aerodynamicists, use a combination of hand calculations, experimental data, and complex numerical codes to simulate air flow around each blade. Aerodynamicists designing gas turbines must predict the locations of the shocks to locate inefficiencies in the flow. In this thesis, three methods of calculating the shock angles are compared: analytical, experimental, and computational. Three different airfoil shapes are tested: a rectangular flat plate, a supersonic diamond, and a turbine airfoil. Cascade tests of the airfoil …

Computational Modeling Of The Friction Stir Welding (Fsw) Process And Of The Performance Of Fsw Joints, Ajay Prasad Arakere

All Theses

Friction Stir Welding (FSW) is a solid-state metal-joining process. Within FSW, a (typically) cylindrical tool-pin (threaded at the bottom and terminated with a circular-plate shape shoulder, at the top) is driven between two firmly-clamped plates (placed on a rigid backing support). Due to a high normal downward pressure applied to the shoulder and due to frictional sliding and plastic-deformation, substantial amount of heat is generated at the tool/work-piece interface and in the region underneath the tool shoulder. Thermally plasticized work-piece material is then extruded around the traveling tool and forged into a welding-joint behind the tool. Due to its solid-state …

Modal Analysis To Minimize Gearbox Induced Noise Of General Electric Wind Turbines, Matthew Evans

All Theses

With the current global emphasis on alternative green energy sources, wind turbine technologies have seen significant growth in recent years. Today, wind turbines are being produced and constructed at unprecedented levels with their sites inching closer and closer to residential communities. With that, wind turbine companies have been receiving growing complains about the noise emitted from these turbines during operation. To resolve this issue, many of these companies are spending more resources to design and manufacture quieter wind turbines. In particular, General Electric (GE) intends to reduce the noise created by their 2.5 MW CGDT wind turbines. Previous studies showed …

Laser-Assisted Printing Of Alginate And Cellular Tubes, Jingyuan Yan

All Theses

Laser-assisted printing such as laser-induced forward transfer (LIFT) has found increasing biofabrication applications as an orifice-free cell/organ printing approach. Unfortunately, there have been very few studies on its efficacy of three-dimensional (3D) printing performance. In addition, the effects of printing parameters on jet/droplet formation during the printing of Newtonian and non-Newtonian fluids are lacking. Therefore, it is important to investigate its printing process and quality. The resulting knowledge will help to better control the resulting printing quality and feature resolution.
The objective of this study is to investigate the feasibility of laser-assisted 3D printing process and its applicability in making …

An Experimental Study On The Influence That Failure Number, Specialization, And Domain Have On Confidence In Predicting System Failures, Somaiah Thimmaiah

All Theses

Design reviews are typically used for three types of design activities: 1) identifying errors, 2) assessing the impact of the errors, and 3) suggesting solutions for the errors. This experimental study focuses on understanding the second issue as it relates to the number of errors considered, the existence of controls, and the level of domain familiarity of the assessor. A set of design failures and associated controls developed for a completed industry sponsored project is used as the experimental design problem. Non-domain individuals (psychology class students), domain generalists (first year engineering students), and domain specialists (graduate mechanical students) are provided …

Three-Dimensional Finite Element Analysis Of Sound Transmission Performance Of Honeycomb Sandwich Structures, Xin Wang

All Theses

Due to the lighter weight of honeycomb structures compared with a cuboid of similar material, honeycomb is widely used in applications requiring a high stiffness to weight ratio. One important honeycomb meta-structure is sandwich composites designed with a honeycomb core between two thin panel layers. The geometry of the honeycomb is formed from periodically spaced, non-overlapping unit cells. An important advantage of cellular materials such as honeycomb is that vibration and acoustic properties can be changed simply by changing the unit cell geometry variables such as included angle, cell wall thickness and length, while keeping the overall dimensions of the …

Vibration And Acoustic Properties Of Honeycomb Sandwich Structures Subject To Variable Incident Plane-Wave Angle Pressure Loads, Jiaxue Yan

All Theses

Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural …

Energy-Vorticity Turbulence Model With Application To Flow Near Rough Surfaces, W. F. Phillips, E. B. Fowler, Doug F. Hunsaker

Mechanical and Aerospace Engineering Faculty Publications

Based on a more direct analogy between turbulent and molecular transport, a foundation is presented for an energy–vorticity turbulence model. Whereas traditional k-εk-ε, k-ωk-ω, and k-ζk-ζ models relate the eddy viscosity to a dissipation length scale associated with the smaller eddies having the highest strain rates, the proposed model relates the eddy viscosity to a mean vortex wavelength associated with the larger eddies primarily responsible for turbulent transport. A rigorous development of the turbulent-energy-transport equation from the Navier–Stokes equations includes exact relations for the viscous dissipation and molecular transport of turbulent kinetic energy. Application of Boussinesq’s analogy between turbulent and …

Prediction Of Discrete Element Parameters For Modeling The Strength Of Sandy Soils In Wheel/Soil Traction Applications, Timothy Reeves

All Dissertations

The problem of wheel performance on deformable soil has been studied for many years, but prior to the rise of computational mechanics, such investigations have been limited to development of analytical and empirical models, as well as experimental research. Such models have merit but are necessarily highly idealized and are limited in their applications. Today, many computational models have been implemented for a wide variety of wheel/soil applications.
For the specific case of sandy (i.e. non-cohesive) soils, in terms of the soil's physics the Discrete Element Method (DEM) provides arguably the most realistic model. In DEM, each element represents a …

Understanding The Role Of Nonlinearities In The Transduction Of Vibratory Energy Harvesters, Ravindra Masana

All Dissertations

The last two decades have witnessed several advances in micro-fabrication technologies and electronics, leading to the development of small, low-power devices for wireless sensing, data transmission, actuation, and medical implants. Unfortunately, the actual implementation of such devices in their respective environment has been hindered by the lack of scalable energy sources that are necessary to power and maintain them. Batteries, which remain the most commonly used power source, have not kept pace with the demands of these devices, especially in terms of energy density. In light of this challenge, the concept of vibratory energy harvesting has flourished in recent years …

Analysis And Design Of A Thermal Capacitor For Use In The Food Industry, Karen Nielson

Undergraduate Honors Capstone Projects

Team Hot Stuff is working with Thermal Management Technologies (TMT) of Logan, UT to explore the concept of a thermal capacitor serving platter. With the funding from TMT, Hot Stuff will design, build, and test a prototype serving platter. This report is written by Hot Stuff for MAE 4800, Capstone Design I; it covers the design and analysis of a serving platter.

Hydrodynamic Impact Analysis And Testing Of An Unmanned Aerial Vehicle, Isabel Bird

Doctoral Dissertations and Master's Theses

Analysis and testing have been conducted to assess the feasibility of a small UAV that can be landed in the water and recovered for continued use. Water landings may be desirable in a number of situations, for example when testing UAVs outside of the territorial waters of the US to avoid violating FAA regulations. Water landings may also be desirable when conducting surveillance missions in marine environments. Although the goal in landing is to have the UAV lightly set down on the water, rough seas or gusty winds may result in a nose-in landing where the UAV essentially impacts the …

Variational Asymptotic Method For Unit Cell Homogenization Of Thermomechanical Behavior Of Composite Materials, Chong Teng

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To seek better material behaviors, the research of material properties has been massively carried out in both industrial and academic fields throughout the twentieth century. Composite materials are known for their abilities of combining constituent materials in or- der to fulfill the desirable overall material performance. One of the advantages of composite materials is the adjustment between stiffness and lightness of materials in order to meet the needs of various engineering designs. Even though the finite element analysis is mature, composites are heterogeneous in nature and can present difficulties at the structural level with the acceptable computational time. A way …

Design And Testing Of Novel Mouthguard With Intermediate Nitinol And Foam Layers, Adam Kessler

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is the aim of this study to investigate a novel mouthguard design that incorporates the use of a nickel-titanium (Nitinol) layer and thin foam layer in addition to EVA layers. It is thought that the Nitinol layer can distribute the force of an impact and that the thin foam layer may absorb this distributed force better than a solid EVA mouthguard of the same thickness. Rectangular, flat coupons representative of several mouthguard configurations were constructed for testing using an instrumented drop-weight impact tower. The coupon configurations include a control made of laminated EVA, a group of laminated EVA and …

Predicting The Performance Of A Solar Domestic Water Heating System With Evacuated Tube Collectors And Hydronic Radiant Flooring, Kimberly Nicole Hammer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Residential solar thermal system installations have been significantly increasing in the last decade and there exists limited resources for reasonably predicting the performance of those systems. A simulated model is developed in MATLAB® and used to predict the performance of a solar domestic water heating system. In the simulated system, hot water is generated using evacuated tube solar collectors and stored in a domestic hot water storage tank, which utilizes immersed coil heat exchangers. The system is designed to provide hydronic radiant floor heating to its occupants based on the heat loss of a building energy model for an energy-efficient …

Design Of Experimental Methods To Test The Performance Of Pads And Helmets Under Blast Loading Conditions, Kurtis Palu

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

Improvised explosive devices (IEDs) have become a primary weapon in conflicts against US and allied forces. Improvements in body armor and medicine have increased the survivability of such events. These factors have caused an increase in traumatic brain injury (TBI) and mild traumatic brain injury (mTBI) induced by primary blast waves. Injury mechanisms caused from primary blast waves are not clearly understood or defined. How primary blast waves interact with materials or between narrow gaps found between helmet pads is not known. Two novel test fixtures were developed to provide a basic understanding of these two issues.

The first fixture …

Hybrid Photothermal Technique For Microscale Thermal Conductivity Measurement, Zilong Hua

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In nuclear reactors, the thermal energy generated from the nuclear reactions needs to be transferred all the way through the core of the fuels to the surrounding steam to be utilized. Therefore, thermal conductivity is considered an important thermophysical property of the fuel which needs to be measured. The nuclear fuel microstructure is known to be damaged by neutronirradiation, which can result in sharp, local changes of thermal conductivity. However, most existing thermal conductivity measurement techniques of nuclear fuel are not able to make high spatial-resolution measurements. The objective of this study was to develop a non-contact thermal conductivity measurement …

Thermo-Piezo-Electro-Mechanical Simulation Of Algan (Aluminum Gallium Nitride) / Gan (Gallium Nitride) High Electron Mobility Transistor, Lorin E. Stevens

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to the current public demand of faster, more powerful, and more reliable electronic devices, research is prolific these days in the area of high electron mobility transistor (HEMT) devices. This is because of their usefulness in RF (radio frequency) and microwave power amplifier applications including microwave vacuum tubes, cellular and personal communications services, and widespread broadband access. Although electrical transistor research has been ongoing since its inception in 1947, the transistor itself continues to evolve and improve much in part because of the many driven researchers and scientists throughout the world who are pushing the limits of what modern …

The Dynamic Analysis Of A Composite Overwrapped Gun Barrel With Constrained Viscoelastic Damping Layers Using The Modal Strain Energy Method, Braydon Day Hall

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

By using composite materials and rubber overwrapped onto a steel liner, a new design for a gun barrel is investigated. Multiple configurations are analyzed and compared using the Finite Element Method and analytical solutions. By alternating layers of composite material and rubber over the steel liner, different reactions in the barrel are obtained when subjected to identical internal pressures from a projectile being fired. The ideal reaction desired from creating this new gun barrel is to dissipate energy more effectively than gun barrels made entirely of steel or overwrapped with just a composite material. The analyses show that multiple thin …

Computational Fluid Dynamics Validation Of Buoyant Turbulent Flow Heat Transfer, Jared M. Iverson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Computational fluid dynamics (CFD) is commonly used to visualize and understand complicated fluid flow and heat transfer in many industries. It is imperative to validate the CFD computer models in order to avoid costly design choices where experimentation cannot be used to ratify the predictions of computer models. Assessments of CFD computer models in the literature conclude that significant errors occur in computer model predictions of fluid flow influenced by buoyancy forces.

The Experimental Fluid Dynamics Laboratory at Utah State University constructed a wind tunnel with which to perform experiments on buoyancy induced fluid flow. The experiments measured the heat …

Verification And Validation Of The Spalart-Allmaras Turbulence Model For Strand Grids, Oisin Tong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The strand-Cartesian grid approach is a unique method of generating and computing fluid dynamic simulations. The strand-Cartesian approach provides highly desirable qualities of fully-automatic grid generation and high-order accuracy. This thesis focuses on the implementation of the Spalart-Allmaras turbulence model to the strand-Cartesian grid framework. Verification and validation is required to ensure correct implementation of the turbulence model.

Mathematical code verification is used to ensure correct implementation of new algorithms within the code framework. The Spalart-Allmaras model is verified with the Method of Manufactured Solutions (MMS). MMS shows second-order convergence, which implies that the new algorithms are correctly implemented.

Validation …

Analysis Of Star Identification Algorithms Due To Uncompensated Spatial Distortion, Steven Paul Brätt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

With the evolution of spacecraft systems, we see the growing need for smaller, more affordable, and robust spacecrafts that can be jettisoned with ease and sent to sites to perform a myriad of operations that a larger craft would prohibit, or that can be quickly manipulated from performing one task into another. The developing requirements have led to the creation of Nano-Satellites, or CubeSats. The question then remains, how to navigate the expanse of space with such a minute spacecraft? A solution to this is using the stars themselves as a means of navigation. This can be accomplished by measuring …

Experimental Studies Of Vertical Mixing Patterns In Open Channel Flow Generated By Two Delta Wings Side-By-Side, Garrett Vaughan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Algae-derived biofuels is a hot topic of research interest when it comes to renewable energy applications. Algae can be grown in open systems that are low-cost, easy to maintain, and open to the environment. However, algae does not grow very dense in these systems. Mixing is an important factor in growing algae. If mixing were to be improved in open systems, the algae may be able to grow more dense. Certain studies show that placing a mechanical device such as an airfoil or airplane wing in the water will be able to increase the capability of mixing in the open …