Mechanical Engineering Commons^™

Functional And Behavioral Product Information Representation And Consistency Validation For Collaboration In Product Lifecycle Activities, Mehmet Murat Baysal

Mechanical and Aerospace Engineering - Dissertations

Information models that represent the function, assembly and behavior of artifacts are critical in the conceptual development of a product and its evaluation. Much research has been conducted in this area; however, existing models do not relate function, behavior and structure in a comprehensive and consistent way. In this work, NIST's Core Product Model (CPM) and the Open Assembly Model (OAM) are extended to integrate product information including function and behavior, with an emphasis on assembly, throughout all phases of product development. For function and flow classification, the NIST functional taxonomy is used to maintain consistency with the literature.

The …

Study Of Vocs Transport And Storage In Porous Media And Assemblies, Jing Xu

Mechanical and Aerospace Engineering - Dissertations

Indoor VOCs concentrations are influenced greatly by the transport and storage of VOCs in building and furnishing materials, majority of which belong to porous media. The transport and storage ability of a porous media for a given VOC can be characterized by its diffusion coefficient and partition coefficient, respectively, and such data are currently lacking. Besides, environmental conditions are another important factor that affects the VOCs emission. The main purposes of this dissertation are: (1) validate the similarity hypothesis between the transport of water vapor and VOCs in porous materials, and help build a database of VOC transport and storage …

A Study On The Effects Of Solar Power, Jonathan Hayes

Electrical Engineering Undergraduate Honors Theses

The utilization of new and alternative energy sources, specifically solar energy, has been on the rise and will continue to grow as we attempt to diminish our use and dependency on older, nonrenewable energy sources. One of the biggest challenges involved with the use of solar energy, or renewable energy in general, is how to provide this energy for general public use. Some of the limiting factors to this are the efficiency in which solar power can be harvested and converted into usable energy, and the cost of the technology to do this. Recent technological developments have included the microinverter, …

Thromboresistance Characterization Of Extruded Nitric Oxide Releasing Silicone Catheters, Kagya Amoako, Christopher Archangeli, Hitesh Handa, Terry Major, Mark E. Meyerhoff, Gail M. Annich, Robert H. Bartlett

Mechanical and Industrial Engineering Faculty Publications

Intravascular catheters used in clinical practice can activate platelets, leading to thrombus formation and stagnation of blood flow. Nitric oxide (NO)-releasing polymers have been shown previously to reduce clot formation on a number of blood contacting devices. In this work, trilaminar NO-releasing silicone catheters were fabricated and tested for their thrombogenicity. All catheters had specifications of L = 6 cm, inner diameter = 21 gauge (0.0723 cm), outer diameter = 12 gauge (0.2052 cm), and NO-releasing layer thickness = 200 ± 11 µm. Control and NO-releasing catheters were characterized in vitro for their NO flux and NO release duration by …

Energy Consumption And Greenhouse Gas Emissions From Commercial And Manufacturing Sectors Specific Studies On Hvac Equipment And Dairy Processing, Aik Jong Tan

Graduate Theses and Dissertations

Commercial and manufacturing sectors in United States consumed approximately 50% of the total End use energy in 2010. In 2009, 81.5% of the greenhouse gas (GHG) emitted in the United States was energy related. From the broad aspects of commercial and manufacturing sectors; two relatively narrow and specific topics, commercial building's HVAC equipment and dairy processing were chosen to increase the understanding of the energy use and GHG emission in these two sectors. Few published studies related to these two specific areas are available. The first study in this thesis discussed the energy use and GHG emissions by HVAC equipment …

Computer Modeling Of The Influence Of Structure Plan Areas On Tornado Forces, Nashmi Hassan M Alrasheedi

Graduate Theses and Dissertations

The study of the conventional Straight Line (SL) wind flow dominates research into wind loads on structures. Most structure design takes into account only research into SL flow. Few researchers have studied tornado forces on buildings and attempted to distinguish between tornadic wind loads and SL flow loads. Using a computer simulation, this research addresses and distinguishes between the tornadic forces and SL forces on structures. In the numerical simulation, tornado forces and SL forces will be compared on large structure plan areas and on thin structure plan areas. Additionally this research investigates how the increase in the vortex strength …

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 …