Mechanical Engineering Commons^™

Design And Implementation Of A Small Electric Motor Dynamometer For Mechanical Engineering Undergraduate Laboratory, Aaron Farley

Graduate Theses and Dissertations

This thesis set out to design and implement a new experiment for use in the second lab of the laboratory curriculum in the Mechanical Engineering Department at the University of Arkansas in Fayetteville, AR. The second of three labs typically consists of data acquisition and the real world measurements of concepts learned in the classes at the freshman and sophomore level. This small electric motor dynamometer was designed to be a table top lab setup allowing students to familiarize themselves with forces, torques, angular velocity and the sensors used to measure those quantities, i.e. load cells and optical encoders. The …

Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, Stephanie Clark

Graduate Theses and Dissertations

Recent advances within the field of cube satellite technology has allowed for the possible development of a maneuver that utilizes a satellite's Low Earth Orbit (LEO) and increased atmospheric density to effectively use lift and drag to implement a noncoplanar orbital maneuver. Noncoplanar maneuvers typically require large quantities of propellant due to the large delta-v that is required. However, similar maneuvers using perturbing forces require little or no propellant to create the delta-v required. This research reported here studied on the effects of lift on orbital changes, those of noncoplanar types in particular, for small satellites without orbital maneuvering thrusters. …

Comparative Fatigue Analysis Of Metals And Polymers For Engineering Applications, Monica Jones

Mechanical Engineering Undergraduate Honors Theses

Rapid prototype polymers are becoming increasingly popular for engineering applications, particularly during the design phase as a quick check for size and fit; however they are not currently widely-used for load-bearing applications. Current research at the University of Arkansas Department of Mechanical Engineering focused on rapid prototyped polymers by doing cyclical tensile testing. The results were analyzed for strain energy and fatigue data. When cycling at lower percentages of ultimate stress, unusual strain energy patterns were observed. This research details testing of metals in order to compare strain energy patterns to those of the rapid prototype polymers.

Effects Of Surface Roughness On The Indoor Particle Deposition Rate Constant, Shaojie Wang

Mechanical and Aerospace Engineering - Dissertations

The purpose of this work was to quantify the deposition rate constants of size-classified particles on typical indoor surface materials as affected by the degree of surface roughness. The experiments were conducted in a small-scale acrylic chamber. The particle size range was from 0.723 to 5.048 £gm with 28 size bins. The air change rates were 6, 11 and 13 h-1. The TSI large particle aerosol generator 8108 was used to generate potassium chloride as test particles, and the TSI aerodynamic particle sizer (APS3321) was used to measure the particle number concentrations. Particle deposition rate constants were determined by regression …

A Double Cantilever Beam Specimen For Foam Core Fracture Characterization, Elio E. Saenz, Adrián Hernández-Pérez, Leif A. Carlsson, Anette M. Karlsson

Mechanical Engineering Faculty Publications

This article presents the analysis and test results for a new sandwich double cantilever beam specimen for foam fracture characterization. The foam is sandwiched between two stiff and strong aluminum adherends. The specimen is analyzed using a modified version of the classical Kanninen elastic foundation model. Finite element analysis is conducted to determine the stress state near the crack tip and compliance of the double cantilever beam sandwich specimen. Model predictions are compared to experimental compliance data and crack growth paths for double cantilever beam specimens with polyvinyl chloride and polyethersulfone foams. The elastic foundation model and finite element analysis …

Sole Power: Pedal Phone Charger Final Report, Nicole Hensley, Anthony Ruh, Krista Schmidt, Joseph Garcia

Mechanical Engineering

The device design was conceived to meet the energy needs of rural populations in India. These communities have cell phones but lack access to reliable grid power, especially during monsoon season. The charger is designed to be affordable, durable, and easily repairable for each owner family. It uses off-the-shelf components and is intended to be replicated by backyard manufacturing startups in developing countries.

Its purpose is to efficiently transfer human foot motion via a treadle, four-bar-linkage, and sprocket-chain step-up to drive a rotor & stator generator from a common gas scooter. The single-phase alternating current from the generator is passed …

Design Of Meta-Materials Outside The Homogenization Limit Using Multiscale Analysis And Topology Optimization, Christopher Czech

All Dissertations

The field of meta-materials engineering has largely expanded mechanical design possibilities over the last two decades; some notable design advances include the systematic engineering of negative Poisson's ratio materials and functionally graded materials, materials designed for optimal electronic and thermo-mechanical performances, and the design of materials under uncertainty. With these innovations, the systematic engineering of materials for design-specific uses is becoming more common in industrial and military uses. The motivation for this body of research is the design of the shear beam for a non-pneumatic wheel. Previously, a design optimization of a finite element model of the non-pneumatic wheel was …

Compressive Strength Of Continuous Fiber Unidirectional Composites, Ronald Thompson

All Dissertations

Dow and Rosen's work in 1965 formed an intellectual framework for compressive strength of unidirectional composites. Compressive strength was explained in terms of micro-buckling, in which filaments are beams on an elastic foundation. They made simplifying assumptions, with a two dimensional idealization and linearized material properties. This study builds on their model, recognizing that the shear mode of instability drives unidirectional compressive strength. As a necessary corollary, the predictive methods developed in this study emphasize correct representation of composite shear stiffness. Non-linear effects related to matrix material properties, fiber misalignment, three dimensional representation, and thermal prestrains are taken into account. …

Relative Navigation And Control Of A Hexacopter, Timothy Mclain, Randal W. Beard, Robert C. Leishman, John Macdonald

Faculty Publications

This paper discusses the progress made on developing a multi-rotor helicopter equipped with a vision-based ability to navigate through an a priori unknown, GPS-denied environment. We highlight the backbone of our system, the relative estimation and control. We depart from the common practice of using a globally referenced map, preferring instead to keep the position and yaw states in the EKF relative to the current map node. This relative navigation approach allows simple application of sensor updates, natural characterization of the transformation between map nodes, and the potential to generate a globally consistent map when desired. The EKF fuses view …

A Conductivity Testing System Coupled With A Tensile Testing Machine To Measure The Surface Properties Of Polymer Specimens, Nguyen T. Nguyen

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

Polymers play an essential role in our everyday life due to their employment in a widespread range of applications. Polymers are used in industries such as space, biomedical, electronics, etc. in which their electrical and mechanical properties are major aspects which need to be investigated prior to implementation. When subjected to mechanical stimulations, polymers may exhibit changes in electrical conductivity which can vary locally within the specimens, especially in those of conducting polymers. In mechanical investigations a tensile testing machine is used to understand polymers’ strength, elasticity or other mechanical properties. In electrical analysis, using a four-point probe to examine …

The Integration Of Propane Flaming And Mechanical Cultivation For Effective Weed Control In Agriculture, Brian D. Neilson

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

Flaming is a thermal weed control method that can kill weeds within or between crop rows using heat. Mechanical cultivation is another weed control method which undercuts weeds between crop rows to kill them. A combination flamer/cultivator implement was designed to take advantage of the good qualities of both flaming and cultivation to provide excellent organic weed control.

Flaming hoods were designed in the spring of 2010 and retrofitted on an existing row crop cultivator. The hoods were tested in corn and soybean field studies in the summer of 2010. Of the seven treatments tested, a treatment of flaming combined …

Study Of Grinding Burn Using Design Of Experiments Approach And Advanced Kaizen Methodology, Kiruthika Devi Sundarrajan

Department of Industrial and Management Systems Engineering: Dissertations, Theses, and Student Research

Grinding burn has been one of the re-occurring issues at a leading automotive manufacturer. Historically when grinding burn occurred, trial and error was used to delicately find a set up process settings that provided good-enough-to-get-by results, but not optimal. Some changes include changing the coolant manifold to improve the coolant flow and rate, changing the grinding wheel, changing the type of coolant. The experiments have proved to introduce some improvements, however the occurrence of grinding burns have not been reduced or quantified and the cause of the grinding burn has not been identified or quantified. Grinding is a complex phenomenon …

Thermally Aware, Energy-Based Techniques For Improving Data Center Energy Efficiency, Dustin W. Demetriou

Mechanical and Aerospace Engineering - Dissertations

This work investigates the practical implementation of so-called thermally aware, energy optimized load placement in air-cooled, raised floor data centers to reduce the overall energy consumption, while maintaining the reliability of the IT equipment. The work takes a systematic approach to modeling the data center's airflow, thermodynamic and heat transfer characteristics - beginning with simplified, physics-inspired models and eventually developing a high-fidelity, experimentally validated thermo-hydraulic model of the data center's cooling and power infrastructure. The simplified analysis was able to highlight the importance of considering the trade-off between low air supply temperature and increased airflow rate, as well as the …

Modeling And Managing Engineering Changes In A Complex Product Development Process, Weilin Li

Mechanical and Aerospace Engineering - Dissertations

Today's hyper-competitive worldwide market, turbulent environment, demanding customers, and diverse technological advancements force any corporations who develop new products to look into all the possible areas of improvement in the entire product lifecycle management process. One of the areas that both scholars and practitioners have overlooked in the past is Engineering Change Management (ECM).

The vision behind this dissertation is to ultimately bridge this gap by identifying main characteristics of a New Product Development (NPD) process that are potentially associated with the occurrence and magnitude of iterations and Engineering Changes (ECs), developing means to quantify these characteristics as well as …

Qualified Affordance-Based Design, Jun Hu

All Theses

Function-based approaches are taught by the engineering design community and implemented in practice. The most significant advantage of these approaches is that they can guide the designers to abstract the essential problems from the design requirements, build the function-based models, and consequently provide the direction of the solution. However, due to the lack of a consistent scientific definition on the meaning of the function, these approaches may be contradictory when representing human-centered aspects, features, and non-physical purposes. To address this issue, design researchers have pursued two general directions: (1) broadening the meaning of function and (2) introducing an alternative scientific …

A Case Study In Challenging And Validating Engineering Requirements With Value-Based Techniques, Seth Crouch

All Theses

Requirements are an essential element to engineering design as they are used to focus idea generation during conceptual design, provide criteria for decision making during concept selection, and verify the chosen concept fulfills product needs. Because they are essential to the entire design process, great emphasis needs to be put on ensuring that they are correct. This research focuses on a value-based methodology useful for challenging and validating established requirements. A case study was conducted using this process on a project involving the design of a vehicle seat. This case study shows that this approach provides more persuasive evidence to …

Assessment Of A Safe Driving Program For Novice Drivers And Smart Jersey Barrier Design To Minimize Animal-To-Vehicle Collisions, Lance Clark

All Theses

Each year, the total number of vehicles, motorists, highway infrastructures, and distance traveled by drivers increases on a global basis. This rise in personal and commercial ground vehicle usage brings with it the advantages of the modern age, but it is not without societal cost. Vehicular incidents result in tens of thousands of deaths each year in the United States alone. For this reason, research has been performed to advance driver safety while simultaneously providing wildlife with means to avoid animal-to-vehicle collisions (AVC). In this thesis, two solutions are proposed: a driver education program with classroom experiences, in-vehicle resources, and …

Charging Kinetics Of Micropores In Supercapacitors, Daniel Oberklein

All Theses

The charging kinetics of Electric Double Layer Capacitors (EDLC) were studied using a continuum model based on the Poisson-Nernst-Planck (PNP) Equations, with the additional modeling of the bulk fluid motion in the electrolyte using the Navier-Stokes Equations. The results demonstrate that the addition of bulk flow modeling yields a faster charging rate and higher charging current due to the additional convective component of the current resulting from the bulk fluid motion. A parametric study was conducted to determine the effect of various physical parameters of the EDLC system on the charging kinetics. Decreased fluid viscosity results in a faster charging …

Automated Assembly Time Prediction Tool Using Predefined Mates From Cad Assemblies, Joseph Owensby

All Theses

Current Design for Assembly (DFA) methods and tools require extensive amounts and types of user inputs to complete the analysis. Since the methods require extensive amounts and types of inputs, certain issues arise: the analysis can become tedious, time consuming, error prone, and not repeatable. These issues eventually lead to the DFA methods being used as a redesign tool or not being implemented at all.
The research presented in this thesis addresses the current DFA limitations and issues by developing and implementing an automated assembly time prediction tool that: extracts explicitly defined connections from SolidWorks assembly models, determines the structural …

Power Generation And Control Of Mechatronics Systems - Theory And Test, Kelly Austin

All Theses

An integrated, multi-disciplined approach to engineering design is a broad definition of mechatronics. Though some mechatronics proponents differ in their definitions of the topic, an interdisciplinary approach to engineering is taken by many industries which should be reflected on campus in the approach to engineering education. In this thesis, two mechatronics systems are investigated. A laboratory experiment is developed for use in the mechanical engineering program at Clemson University, and a thermoelectric power generation from diesel engine exhaust heat is investigated as an automotive industry application.
An electromagnet excited masspendulum system with attached spring and damper elements is introduced as …

Finite Element Modeling And Design Of Honeycomb Sandwich Panels For Acoustic Performance, David Griese

All Theses

Honeycomb cellular metamaterial structures offer many distinct advantages over homogenous materials because their effective material properties depend on both their constituent material properties and their geometric cell configuration. From this, a wide range of targeted effective material properties can be achieved thus supporting forward design by tailoring the honeycomb cellular materials and properties for specific applications. One area that has not been fully explored is the set of acoustic properties of honeycomb materials and how these can offer increased design flexibility when targeting acoustic performance. Understanding these relations, the designer can effectively tune designs to perform better in specific acoustic …

Set Up Time Reduction And Quality Improvement On The Shop Floor Using Different Lean And Quality Tools, Seetha Ram Bavuluri

All Theses

The purpose of this thesis document is to describe a method developed for reducing setup time in machining processes and simultaneously improve the quality of production after setup. Bosch Rexroth at Fountain Inn is a semi-automated plant and is still in its initial stages of standardizing the setup process. Setup time at different machining centers includes: machining time, inspection time, loading and unloading times and deburring. The focus of the described method is in reducing setup times related to inspection time and loading and unloading times. To achieve success in these problems the following new tools were developed: first piece …

Polycart, Ryan Bolton, Vincent Contreras, Rodrigo Sanchez

Mechanical Engineering

No abstract provided.

Adding Cerebral Autoregulation To A Lumped Parameter Model Of Blood Flow, Russell Gentile

HIM 1990-2015

A mathematical model of blood flow in infants with hypoplastic left heart syndrome (HLHS) was improved by adding cerebral autoregulation. This is the process by which blood vessels constrict or dilate to keep blood flow steady in certain organs during pressure changes. The original lumped parameter model transformed the fluid flow into an electrical circuit. Its behavior is described using a system of thirty-three coupled differential equations that are solved numerically using a fourth-order Runge-Kutta method implemented in MATLAB. A literature review that includes a discussion of autoregulation mechanisms and approaches to modeling them is followed by a description of …

Reduction Of Solid-Solid Thermal Boundary Resistance By Inserting An Interlayer, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Effective Method is Proposed to Greatly Improve the Thermal Transport Across the Interface between Two Solids with Dissimilar Phonon Spectra. If the Two Solids Have Similar Crystal Structure and Lattice Constant, It is Predicted from the Molecular Dynamics Modeling that an over 50% Reduction of the Thermal Boundary Resistance Can Be Achieved by Inserting a 3-Unit-Cell-Thick Interlayer Whose Debye Temperature is Approximately the Square Root of the Product of the Debye Temperatures of the Two Solids. on the Other Hand, If the Two Solids Have a Large Difference in Lattice Constant, It is Found the Interfacial Atomic Restructuring Plays …

Novel Heavy Duty Engine Concept For Operation Dual Fuel H 2-Nh3, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A prior paper has presented a novel design of a heavy-duty truck engine fueled with H2. in this design, the customary in-cylinder Diesel injector and glow plug are replaced with a main chamber fuel injector and a jet ignition pre-chamber. the jet ignition pre-chamber is a small volume that is connected to the in-cylinder through calibrated orifices accommodating another fuel injector and a glow or a spark plug that controls the start of combustion. This design permits to operate the engine in four different modes: traditional compression ignition (CI), diffusion, Diesel-like (M1); mixed gasoline/Diesel-like (M2); traditional spark ignition (SI), premixed, …

The Use Of A Pylon Mounted Transducer For Investigating The Gait Of Transtibial Amputees, Justin Robert Brink

UNLV Theses, Dissertations, Professional Papers, and Capstones

Two areas of research interest in the design and use of lower limb prosthetic devices are how foot performance varies with design and how prosthesis alignment affects gait. The current study addressed both of these areas through the use of the JR3 triaxial transducer mounted at the base of the socket. The transducer is an innovative form of instrumentation that measures forces and moments at the end of the socket. Traditional measurement of gait uses a force plate buried in the floor of a gait laboratory. The study established that the transducer offers a viable means of instrumentation for amputee …

Upgrading Unlv's Astm E477 Test Facility To Meet The Current Standards Of Astm E477, Ronn Fojas

UNLV Theses, Dissertations, Professional Papers, and Capstones

A by-product of Heating, Ventilation, and Air-conditioning (HVAC) systems is noise that is produced by fans, compressors, and other related equipments and the noises from the turbulence that is created by moving air. Sometimes, it is impractical to modify the sources of the noise, which requires designers to modify the path of the noise, the duct system. These modifications might include installing an in-duct silencer or acoustical lining on the inside walls of the ducts. The testing and the precise quantification of the performance of these silencers and duct linings are necessary for any designer to be able to make …

Improving Efficiency And Capacity Of Hydro-Turbines In The Western United States, Hoover Dam, Jonathan Sanchez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal for this thesis is to minimize clearances and tolerances, in order to prevent water leakage. A proper seal on the seal rings does not let excess water flow through the turbine runner, thus conserving more water and wasting less energy. Moreover, water leakage past worn wear plates allows for an extra load for the turbine when operating in condense mode. When the wicket gates are closed, water leakage past worn plates wastes mechanical energy in the water; thus, decreasing the efficiency of the Francis turbine, especially when operating at partial loads. Furthermore, the wicket gates also known as …

Computational Fluid Dynamics Analysis Of Butterfly Valve Performance Factors, Adam Del Toro

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Butterfly valves are commonly used to control fluid flow inside of piping systems. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As a butterfly valve is rotated open, fluid is able to more readily flow past the valve. A butterfly valve’s design is important to understand and is commonly characterized by its own performance factors. How a butterfly valve will perform, while in operation at different opening angles and under different types of flow, is critical information for individuals planning and installing piping systems involving the valve. …