Engineering Commons^™

Modeling Aspects Of Magnetic Actuators And Magnetic Suspension Systems, V. Dale Bloodgood Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation is a study of new modeling techniques developed for magnetic suspension systems. The techniques discussed are modifications of magnetic circuit theory and fundamental eddy current models. The techniques are compared against experimental test results and finite element data. The information gained from the experimental testing is used to provide insight into magnetic bearing design.

A small-gap modeling technique called extended circuit theory is developed that incorporates information about the system gained from finite element data, or experimental data, to be included in the analytic model. The variations between the classical magnetic circuit model and the finite element model …

Generic Cost Estimation Framework For Design And Manufacturing Evaluation, Uday A. Kilkami

Mechanical & Aerospace Engineering Theses & Dissertations

A major drawback of current cost estimation models is their incapability of embracing effectively complete product development stage. Parametric estimation works well in early stages of design, but in detail design stage, a more complete estimation is provided by process model based and detail estimation techniques. A major paradigm shift is proposed in this work whereby ‘Cost’ is to be considered as a design parameter from scientific perspective, and it is to be treated as a design consequence rather than as an operational outcome. A comprehensive framework using System Analysis fundamentals is designed to study ‘Process Cost’ aspects of part …

Effects Of Shot-Peening On High Cycle Fretting Fatigue Behavior Of Ti-6al-4v, Halil I. Yuksel

Theses and Dissertations

Effects of Shot-peening on High Cycle Fretting Fatigue behavior of Ti-6Al-4V were investigated. Experiments were performed with 6.35 mm thick specimens which provided S/N curves. After the tests, it was observed that the specimens failed near the trailing edge of contact. Scanning Electron Microscopy showed that cracks initiated on the contact surface for 6.35 mm, and at the depth of specimen ranging from 200 to 300 microns for 3.81 mm thick specimens. Initial crack orientation was around 37 and 42 degrees respectively for 6.35 and 3.81 mm thicknesses. Finite Element Analysis (FEA) was conducted, and using FEA results, Smith-Watson-Topper, Findley, …

Fabrication Techniques For Iii-V Micro-Opto-Electro-Mechanical Systems, Jeremy A. Raley

Theses and Dissertations

This thesis studies selective etching techniques for the development of Al_xGa_1-xAs micro-opto-electro-mechanical systems (MOEMS). New MEMS technology based on materials such as Al_xGa_1-xAs enables the development of micro-systems with embedded active micro-optical devices. Tunable micro-lasers and optical switching based on MOEMS technology will improve future wavelength division multiplexing (WDM) systems. WDM vastly increases the speed of military communications and sensor data processing. From my designs, structures are prepared by molecular beam epitaxy. I design a mask set for studies of crystal plane selectivity. I perform a series of experiments on the selective …

The Effect Of The Thermal Barrier Coating On The Displacement Instability In Thermal Barrier Systems, Anette M. Karlsson, T. Xu, A. G. Evans

Mechanical Engineering Faculty Publications

Thermal barrier systems are susceptible to instability of the thermally grown oxide (TGO) at the interface between the bond coat and the thermal barrier coating (TBC). The instabilities have been linked to thermal cycling and initial geometrical imperfections, as well as to misfit strains due to both oxide growth and thermal expansion misfit. Numerical simulations are used to investigate the role of the thermo-mechanical properties of the TBC in this instability. It is found that the TBC constrains the deformation, whereupon instabilities develop preferentially in regions where crack-like imperfections either pre-exist in the TBC or are created because of the …

Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Bioenergetics is concerned with the energy conservation and conversion processes in a living cell, particularly in the inner membrane of the mitochondrion. This review summarizes the role of thermodynamics in understanding the coupling between the chemical reactions and the transport of substances in bioenergetics. Thermodynamics has the advantages of identifying possible pathways, providing a measure of the efficiency of energy conversion, and of the coupling between various processes without requiring a detailed knowledge of the underlying mechanisms. In the last five decades, various new approaches in thermodynamics, non-equilibrium thermodynamics and network thermodynamics have been developed to understand the transport and …

A Reduced–Cost Mechanized System For Handling And Curing Mechanically–Harvested Burley Tobacco, Greg A. Camenisch, Larry G. Wells, Timothy D. Smith, George A. Duncan

Biosystems and Agricultural Engineering Faculty Publications

An experimental system was tested in which mechanically harvested burley tobacco plants placed onto steel slotted receivers were retrieved from a field, transported to a field curing structure, and placed onto the structure for air curing by a single worker. The system consisted of a tractor–towed, trailer mechanism that engaged and hoisted loads of approximately 360 burley plants of approximately 1 Mg mass. Ten slotted steel rails, 3.05 m long, holding 36 notched plants were placed onto parallel wooden beams suspended at a height of 2.13 m by wooden posts set in the ground. Burley tobacco was cured in this …

Analytical Derivation Of A Coupled-Circuit Model Of A Claw-Pole Alternator With Concentrated Stator Windings, Hua Bai, Steven Pekarek, Jerry L. Tichenor, Walter Eversman, Duane J. Buening, Gregory R. Holbrook, Michael L. Hull, Ronald J. Krefta, Steven J. Shields

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A lumped-parameter coupled-circuit model of a claw-pole alternator is derived. To derive the model, analytical techniques are used to define a three-dimensional (3-D) Fourier-series representation of the airgap flux density. Included in the series expansion are the harmonics introduced by rotor saliency, concentrated stator windings, and stator slots. From the airgap flux density waveform, relatively simple closed-form expressions for the stator and rotor self- and mutual-inductances are obtained. The coupled-circuit model is implemented in the simulation of an alternator/rectifier system using a commercial state-model-based circuit analysis program. Comparisons with experimental results demonstrate the accuracy of the model in predicting both …

Design And Fabrication Of Micro-Electro-Mechanical Structures For Tunable Micro-Optical Devices, Michael C. Harvey

Theses and Dissertations

Tunable micro-optical devices are expected to be vital for future military optical communication systems. In this research I seek to optimize the design of a microelectromechanical (MEM) structure integrated with a III-V semiconductor micro-optical device. The resonant frequency of an integrated optical device, consisting of a Fabry-Perot etalon or vertical cavity surface emitting laser (VCSEL), may be tuned by applying an actuation voltage to the MEM Flexure, thereby altering the device's optical cavity length. From my analysis I demonstrate tunable devices compatible with conventional silicon 5V integrated circuit technology. My design for a Fabry-Perot etalon has a theoretical tuning range …

Fretting Fatigue Behavior Of A Titanium Alloy Ti-6al-4v At Elevated Temperature, Onder Sahan

Theses and Dissertations

The purpose of this research is to investigate the fretting fatigue behavior of the titanium alloy Ti-6Al-4V at elevated temperature is investigated. Fretting and plain fatigue experiments are conducted at 260 °C. Crack initiation location and crack initiation orientation is measured and fretting and plain fatigue life data of the specimens from these tests are obtained. Fatigue parameters capable of predicting the number of cycles to specimen failure, the crack location and the crack orientation along the contact surface are analyzed. The parameters are calculated by using the computed stresses and strains obtained from the finite element analysis. The mechanisms …

A Simple Dynamics Experiment Based On Acoustic Emission, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

This paper describes a simple experiment well suited for an undergraduate course in mechanical measurements and/or dynamics, in which physical information is extracted from an acoustic emission signature. In the experiment, a ping–pong ball is dropped onto a hard table surface and the audio signal resulting from the ball–table impacts is recorded. The times between successive bounces, or “flight times”, are used to determine the height of the initial drop and the coefficient of restitution of the impact. The experiment prompts questions about modeling the dynamics of a simple impact problem, including the use of the coefficient of restitution and …

Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Bioenergetics is concerned with the energy conservation and conversion processes in a living cell, particularly in the inner membrane of the mitochondrion. This review summarizes the role of thermodynamics in understanding the coupling between the chemical reactions and the transport of substances in bioenergetics. Thermodynamics has the advantages of identifying possible pathways, providing a measure of the efficiency of energy conversion, and of the coupling between various processes without requiring a detailed knowledge of the underlying mechanisms. In the last five decades, various new approaches in thermodynamics, non-equilibrium thermodynamics and network thermodynamics have been developed to understand the transport and …

Examination Of Contact Width On Fretting Fatigue, Russell S. Magaziner

Theses and Dissertations

The primary goal of this study was to find the effects on the fretting fatigue life when systematically holding the fretting fatigue variables, peak contact pressure, maximum/minimum nominal bulk stress, and the ratio of shear traction to pressure force constant while varying the contact semi-width through changes in pad radius and normal load. Experimental tests were performed on a test setup capable of independent pad displacement. Analytical and finite element simulations of the different experimental tests were performed. The local mechanistic parameters were inspected. Five different critical plane based fatigue predictive parameters lacked effectiveness in predicting changes in life with …

Suggested Methodologies For Determining The Shgc Of Complex Fenestration Systems For Nfrc Ratings, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

Simple fenestration systems, for the purpose of this paper, are those whose solar heat gain and visible transmittance performances can be accurately simulated using the Window 4 or 5 programs developed at Lawrence Berkeley National Laboratory (LBNL). Complex fenestrations are everything else, including obscure or "privacy" glazing, corrugated or otherwise complex patterned glazing, curved, bent, or domed glazing, fritted glazing, glass blocks, glass fiber reinforced plastic daylighting panels, and glazings with internal or attached shading systems of a variety of types. The latter include exterior awnings and overhangs, attached exterior shade screens and shutters (including roll-up shutters), between-the-panes shades, including …

Modeling, Fabrication, And Optimization Of Niobium Cavities – Phase I: Quarterly Progress Report November 20, 2001 - February 20, 2002, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Multipacting is one of the major loss mechanisms in RF superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch. A nonuniform surface etch will leave some unclean areas with contaminants and micron size particles. These significantly affect multipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical …

Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner

Mechanical Engineering Faculty Publications

We previously reported that the probability of an older adult recovering from a forward trip and using a “lowering” strategy increases with decreased walking velocity and faster response time. To determine the within-subject interaction of these variables we asked three questions: (1) Is the body orientation at the time that the recovery foot is lowered to the ground (“tilt angle”) critical for successful recovery? (2) Can a simple inverted pendulum model, using subject-specific walking velocity and response time as input variables, predict this body orientation, and thus success of recovery? (3) Is slower walking velocity or faster response time more …

Numerical Simulation Of Mechanofusion System For Dry Particle Coating Process, Wenliang Chen

Dissertations

A numerical simulation of the Meclianofusion device for dry particle coating is carried out using Discrete Element Method (DEM) technique. In dry particle coating, tiny sub-micron guest particles are coated onto larger micron sized host particles by using mechanical forces, which the Mechanofusion device provides. It consists of a rotating cylindrical chamber that contains the powder mixture, a stationary inner piece (which has a cylindrical surface at the end), and a fixed scraper blade, which prevents powder from caking against the chamber wall. The simulation studies are performed on two scales: system scale to investigate the particle-particle and particle system …

Experimental And Numerical Study Of Flow Characteristics And Segregation In Flow Enhanced Systems, Gregory James

Dissertations

In the study of granular materials, two major topics of importance are powder flow enhancement mechanisms and the flow characterization. This dissertation is involved with both of these topics. With respect to the powder flow enhancement, this study involves investigation of two types of flow enhancement methods. The first flow enhancement method examined is a novel method called the Magnetically Assisted Powder Flow (MAPF) method. In the MAPF, small magnetic particles and powders are placed in a test hopper. A mesh is placed at the bottom of the hopper to hold the magnetic particles while the powder is discharged through …

Computation And Control Of Flow-Induced Noise Behind A Circular Cylinder Using An Acoustic Analogy Approach, Sirivit Taechajedcadarungsri

Dissertations

The computational aeroacoustics (CAA) research, which focuses on predicting acoustics by means of advanced numerical techniques, has recently gained a great deal of progress. In most applications, the prediction of both the sound source and its far-field propagation is necessary as required by regulations. Recently, powerful computers and reliable algorithms have allowed the prediction of far-field noise through the use of Computational Fluid Dynamics (CFD) data as near-field sound sources. One of the most useful analytical methods, used for the computation of noise, is Lighthill's acoustic analogy. The latter will be used in the present study.

Lighthill's acoustic analogy, combined …

Jan 2002, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Newsletter Report Museum Open House 149 visitors

Ole Miss Engineer 2002

Ole Miss Engineer

No abstract provided.

Sunsmart Community Partnerships: Summary And Lessons Learned Report, Florida Solar Energy Center, Jennifer Szaro

FSEC Energy Research Center®

Through a working partnership with the Florida Municipal Electric Association (FMEA), the Florida Solar Energy Center (FSEC), the Florida Municipal Power Agency (FMPA), the Legal Environmental Assistance Foundation (LEAF), and FMEA member utilities, the SunSmart program offers a unified, low-cost solution to providing municipal electric customers with a solar energy option. It also provides its member utilities with a high level of technical and administrative support to alleviate concerns about working with an unfamiliar electric generation technology. It relies on a core team to develop a standardized marketing and public outreach plan which can be utilized by all participants, and …

Acoustic Competition In The Gulf Toadfish Opsanus Beta: Acoustic Tagging, Robert F. Thorson, Michael L. Fine

Biology Publications

Nesting male gulf toadfish Opsanus beta produce a boatwhistle advertisement call used in male–male competition and to attract females and an agonistic grunt call. The grunt is a short-duration pulsatile call, and the boatwhistle is a complex call typically consisting of zero to three introductory grunts, a long tonal boop note, and zero to three shorter boops. The beginning of the boop note is also gruntlike. Anomalous boatwhistles contain a short-duration grunt embedded in the tonal portion of the boop or between an introductory grunt and the boop. Embedded grunts have sound-pressure levels and frequency spectra that correspond with those …

The Wright Stuff: A Redesign Of The 1905 Wright Flyer, Adam Richards, Ben Case, Eric Peterson, Nathan Holman, Wayne Goodrich, Amy Hintze, Carson Esplin, David Christensen, Jonathan Holfeltz, Nick Filimoehala, Nicholas Alley

Mechanical and Aerospace Engineering Capstone Projects

No abstract provided.

Strongly Screened Vortex Lattice Model With Disorder, C. Giardina', Nikolai V. Priezjev, J. M. Kosterlitz

Mechanical and Materials Engineering Faculty Publications

The three dimensional XY model with quenched random disorder and finite screening is studied. We argue that the system scales to model with λ≃0≃T and the resulting effective model is studied numerically by defect energy scaling. In zero external field we find that there exists a true superconducting phase with a stiffness exponent θ≃+1.0 for weak disorder. For low magnetic field and weak disorder, there is also a superconducting phase with θ≃+1.0 which we conjecture is a Bragg glass. For larger disorder or applied field, there is a non superconducting phase with θ≃−1.0. We estimate the critical external field whose …

A Functional Basis For Engineering Design: Reconciling And Evolving Previous Efforts, Julie Hirtz, Robert B. Stone, Daniel A. Mcadams, Simon Szykman, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In engineering design, all products and artifacts have some intended reason behind their existence: the product or artifact function. Functional modeling provides an abstract, yet direct, method for understanding and representing an overall product or artifact function. Functional modeling also strategically guides design activities such as problem decomposition, physical modeling, product architecting, concept generation, and team organization. A formal function representation is needed to support functional modeling, and a standardized set of function-related terminology leads to repeatable and meaningful results from such a representation. We refer to this representation as a functional basis; in this paper, we seek to reconcile …

A Comparison Of The Level Of Maturity Of Manufacturers In The Lake Land College School District In Lean Manufacturing Techniques As Compared To Goodson's Survey Data, Mark W. Henderson

Masters Theses

The purpose of this study was to determine if manufacturers in the Lake Land College School District have implemented Lean Manufacturing techniques and score as high as the manufacturers in Goodson's Michigan study. Lean Manufacturing techniques have revolutionized the auto industry, with the Toyota Production system the benchmark in Lean Manufacturing techniques. A survey using Goodson's Rapid Plant Assessment compares the level of maturity in the utilization of the Lean Manufacturing techniques with the manufacturers in the Lake Land College School District and Goodson's survey of manufacturers in Michigan. The mean score of 57.67 for the manufacturers in the Lake …

Diabetic Patients Foot Care Using Smart Materials To Prevent Ulcerations/Amputations, Carrie Hahn, Ajay Mahajan, Marco P. Schoen

Mechanical Engineering Faculty Research

A major cause of illness and disability in diabetic patients is complications affecting the lower limbs, particularly the feet where loss of feeling may result in ulcerations, and ultimately to partial or total amputation. Traditional remedies for this problem still remains in measuring the foot pressures and then designing a passive shoe insert that absorbs the high pressures. This process may then be repeated multiple times during the lifetime of the patient. This paper describes the conceptual design of an automatic system that monitors and controls the pressure levels in diabetic patients’ feet in real time. The scheme is based …

Real-Time Measurement Of Surface Deformation Of Rotating Blades, Jay Maudlin, Ajay Mohan Mahajan, Tsuchin P. Chu

Mechanical Engineering Faculty Research

This paper presents the results for the real-time measurement of surface deformation of rotating elements. A digital image correlation technique is used to estimate the surface displacements and strains. Speckle patterns are spray painted on the surface of interest and digital images taken before and during deformation caused by rotary motion. The digital image of the deformed blade is taken by freezing the speckled pattern with the help of a stroboscope. The technique provides several advantages over traditional methods in terms of obtaining whole-field deformation profiles, a non-invasive measurement scheme, and a simple and economical set-up. Results are presented for …

Analysis Of Short Crack Growth In Particulate Composites, Ying Zhang, Tsuchin P. Chu, Ajay Mohan Mahajan, Chi Tsieh Liu

Mechanical Engineering Faculty Research

This paper presents the analysis of the short-crack propagation and growth in particulate composite materials by using the image correlation techniques and fracture mechanics theory. The fracture mechanics model for a long crack does not work very well with short-crack propagation when the initial crack length is less than 5.1 mm (0.2 inch). In order to investigate the short crack effect, a series of tests of particulate composite specimens with long and short cracks have been performed and the results were recorded on a video tape. These test data were analyzed to determine the strain fields near the crack tip, …