Engineering Commons^™

Fiber Enhanced Viscoelastic Damping Polymers And Their Application To Passive Vibration Control, Houchun Xia

Mechanical & Aerospace Engineering Theses & Dissertations

A new composite damping material is investigated, which consists of a viscoelastic matrix and high elastic modulus fiber inclusions. This fiber enhanced viscoelastic damping polymer is intended to be applied to light-weight flexible structures as surface treatment for passive vibration control. A desirable packing geometry for the composite material is proposed, which is expected to produce maximum shear strain in the viscoelastic damping matrix. Subsequently, a micromechanical model is established in which the effect of fiber segment length and relative motion between neighboring fibers are taken into account. Based on this model, closed form expressions for the effective storage and …

Light Injection From An Active Cladding To The Core Of A Fiber Optic Fluorosensor, Alvin Leon Bryant

Electrical & Computer Engineering Theses & Dissertations

A fluorosensor works on the basis of light injection from the clad into the core of an optical fiber. The sensitivity of such a sensor depends on the efficiency of light injection. Conditions necessary for a high injection efficiency are experimentally determined. The refractive index difference between the core and the clad,ⁿcore ^-nclad, must be maximized to achieve a high injection efficiency. Since an air clad has the least refractive index, a bare core fiber will have a maximum efficiency. Standard optical fibers used for communication employ a minimum value for ⁿcore ^-nclad, in order …

Study Of Single-Fiber Fiber Optic Lever Microphone, Trung Duc Nguyen

Electrical & Computer Engineering Theses & Dissertations

Fiber optic sensors are widely used in today's technological applications, providing many advantages that conventional sensors lack. In particular, there is a demand in hypersonic applications to develop microphones to measure acoustic pressure that performs in high temperature and noisy surroundings. This thesis analyzes fiber optic lever microphones (FOLM), since they perform at high temperatures. An FOLM system is an intensity modulated sensor, which is simple to implement and is small in size. Two models of the FOLM have been fabricated and calibrated. The first model uses a seven-element fiber array while the second uses a single-fiber to transmit and …

Thermal Behavior Of A Stratified Cylindrical Energy Storage Tank, Sheherazad Youssef Ezz Eldeen Ahmed Korayem

Archived Theses and Dissertations

No abstract provided.

Bulletin No 4242 - The Lyre Trellis For Viticulture, Alain Carbonneau Dr, Vincent P. Desplat, John F. Elliott, Peter Watt

Bulletins 4000 -

The lyre vine training system uses wide rows, an open canopy, and shoot positioning to increase grape maturity and quality while maintaining production levels. It is so named because the end-on view of the vine canopy trained to this type of trellis resembles the shape of the musical instrument, the lyre.

This improvement in quality has not only been established in the diverse experimental vineyards of the National Institute for Agronomic Research (INRA) in France but also in many commercial vineyards throughout the major wine growing regions of the world.

An Expert System For Design, Materials Selection And Manufacture Of Frp Liquid Containers, Khalid Mahmoud Abdel Ghany

Archived Theses and Dissertations

No abstract provided.

Machine Interference Problems In Robot Served Manufacturing Systems Under Priority Analysis Considerations, Amr Fawzi Hamed

Archived Theses and Dissertations

No abstract provided.

A Technical Paper On Automated Pouring And The Selection Process Used By One North American Foundry, R. Stanley Weaver

Graduate Research Papers

This report on automated pouring focuses on the selection process used by one North American iron foundry. The problem facing this facility and any operation wishing to implement this technology lies in the number of variables which must be addressed in their quest for a suitable system.

Influence Of Processing Techniques On Copper Deep Levels Formation And On Photoconductivity In Silicon Doped Gallium Arsenide, Lucy M. Thomas

Electrical & Computer Engineering Theses & Dissertations

Diffusion of copper in silicon doped gallium arsenide under different diffusion conditions is studied. Copper compensated silicon doped gallium arsenide (GaAs:Si:Cu) is used as switch material for bulk optically controlled semiconductor switch, and on-state photoconductivity of the switch is primarily due to the properties of the copper deep levels introduced in the material during diffusion. Gallium arsenide being a compound semiconductor, presence of vacancies and defects make the study of diffusion a complex process. The objective of the current research is twofold: a) to study the influence of diffusion conditions and processing techniques on copper deep level formation in silicon …

The Effects Of Electron Radiation On The Glass Transition Temperature Of A Polyetherimide, Kristen Tulloch Kern

Physics Theses & Dissertations

The effects of electron radiation on a polyetherimide (PEI), Ultem*, were investigated. In particular, the changes in the glass transition temperature (T_g) with absorbed radiation dose were studied. The polymer was exposed to mono-energetic beams of 100-keV electrons and 1.0-MeV electrons for doses up to 100 megagray (MGy). Dosimetry for the exposures was based on Monte-Carlo simulations of the transfer of energy from an energetic electron to the polymer and on comparison to Nylon standards. Dynamic mechanical analysis was used to determine the (T_g) for non-exposed PEI and the changes in (T_g) resulting from …

Silicon Carbide/Electroless Nickel Composite Plating For Aluminum Substrates, Ben Charbit

Masters Theses

The effectiveness of producing a composite coating by suspending micron-sized particles in an electroless nickel bath while plating a 2024T4 aluminum alloy part was studied. The variation in the count of particles trapped in the nickel coating due to changes in the particle size, concentration of the particles in the bath, and the substrate surface texture was also studied. Particle sizes of 1 micron and 10 microns, concentrations of 15 gr/lt and 30 gr/lt, and polished and blasted textures were used. It was found that this technique is an effective way to produce composite coatings rendering a high number of …

Evaluation Of Yba,Cu,O,_, Bulk Superconductors For High Field Magnet Applications, K. Y. Blohowiak, D. F. Garrigus, T. S. Luhman, K. E. Mccrary, M. Strasik, I. A. Aksay, Fatih Dogan, W. B. Hicks, J. Liu, M. Sarikaya

Materials Science and Engineering Faculty Research & Creative Works

Processing of YBCO single crystals was carried out by solidification of semi-liquid YBCO composition using a seeding technique. Microstructural characterization of the pinning centers was investigated by transmission electron microscopy. Characterization of single crystals was carried out, relating grain size and shape to the corresponding flux profiles. Current densities were calculated based on measured trapped fields. Once circulating currents were established, flux pumping and quenching experiments were conducted. These large single crystals will be incorporated into electromagnetic forming devices for use in the military and commercial aircraft manufacturing and service industries.

Evaluation Of Yba2cu3o7-X Bulk Superconductors For High Field Magnet Applications, K. Y. Blohowiak, D. F. Garrigus, T. S. Luhman, K. E. Mccrary, M. Strasik, Ilhan A. Aksay, Fatih Dogan, W. B. Hicks, J. Liu, M. Sarikaya

Materials Science and Engineering Faculty Research & Creative Works

Processing of YBCO single crystals was carried out by solidification of semi-liquid YBCO composition using a seeding technique. Microstructural characterization of the pinning centers was investigated by transmission electron microscopy. Characterization of single crystals was carried out, relating grain size and shape to the corresponding flux profiles. Current densities were calculated based on measured trapped fields. Once circulating currents were established, flux pumping and quenching experiments were conducted. These large single crystals will be incorporated into electromagnetic forming devices for use in the military and commercial aircraft manufacturing and service industries.

Structural Materials From Recycled High Density Polyethylene And Herbaceous Fibers, And Method For Production, Barton L. Bergquist, Mohammed F. Fahmy

Patents (University of Northern Iowa)

A composite useful for structural components comprised of recycled high density polyethylene and herbaceous fibrous materials and a method to produce composites based on recycled high density polyethylene and chopped herbaceous fibers. An alternative structural composite is disclosed which is comprised of recycled low density polyethylene and chopped herbaceous fibrous material.

Design And Performance Evaluation Of A Gas Chromatograph Micromachined In A Single Crystal Silicon Substrate, Rocky R. Reston

Theses and Dissertations

This investigation designed and developed a miniature gas chromatograph (GC) using silicon micromachining techniques. The GC is composed of a miniature sample injector (10 µl sample loop); a 0.9 m long, rectangular-shaped (300 µm width and 10 micrometers height) capillary column coated with a 0.2 µm thick copper phthalocyanine (CuPc) stationary phase; and a dual-detector scheme incorporating a CuPc-coated chemiresistor and a 125 µm diameter thermal conductivity detector bead. Micromachining was employed to fabricate the sample injector interface, the GC column, and the dual-detector cavity. A novel processing technique was developed to sublime the CuPc stationary phase coating on the …

Luminescence Study Of Ion-Implanted And Mbe-Grown Er-Doped Gaas And AlXGa1-XAs, Jose E. Colon

Theses and Dissertations

The excitation and de-excitation mechanisms of the 1.54 microns emissions, from ion implanted and MBE grown GaAs:Er and Al_xGa_1-xAs:Er, were studied through luminescence experiments. Experimental techniques included photoluminescence, time resolved photoluminescence, and selective excitation photoluminescence. The Er³⁺ emissions were studied as a function of Er concentration, aluminum mole friction, n- and p-type doping level, and annealing temperature. In addition oxygen co-doping studies were done in order to determine the role played by oxygen in the Er³⁺ luminescence.

An Investigation Of Graphite Peek Composite Under Compression With A Centrally Located Circular Discontinuity, Benjamin Wham Ii

Theses and Dissertations

The purpose of this thesis was to determine (both experimentally and analytically) the initiation and progression of failure, stress-strain response, and the failure loads of Graphite/Polyetheretherketone (Gr/PEEK) laminates, incorporating a centrally located circular discontinuity, loading in axial compression at room temperature. The laminates studied were (0°)₁₆,(90°)₁₆, (0°/90°)_4S, (± 45°)_4S, and (0°/±45°/90°)_2S. The specimens were loaded within a Boeing Open Hole Compression Fixture. The micromechanical failure modes were identified using a Scanning Electron Microscope. The analytical progression of failure was predicted using a nonlinear finite element code developed by Dr. R.S. …

Synthesis And Characterization Of Lpcvd Boron Nitride Films For X-Ray Lithography, Wen-Pin Kuo

Theses

Boron nitride thin films were deposited on silicon and fused quartz substrates using ammonia and the liquid precursor borane-triethylamine complex (TEAB) by low pressure chemical vapor deposition over a temperature range of 300-850°C, a pressure range of 0.21-0.6 torr, and an ammonia flow rate range of 0-740 sccm. An increased in the nitrogen content in the film due to the addition of ammonia flow resulted in a pronounced improvement in the optical transmission, an increase in the film uniformity and a decrease in the depletion effect. IR spectra of the films showed an asymmetrical wide band centered around 1400 cm …

Mechanical Properties Of Whisker-Reinforced Cordierite Glass Matrix Composites, John R. Dillingham

Opportunities for Undergraduate Research Experience Program (OURE)

The development of a whisker-reinforced ceramic matrix composite has been shown to be a reasonable method of achieving improved mechanical properties for ceramic materials. In this work a cordierite matrix was reinforced with 20vol% of silicon carbide whiskers. The mechanical properties of this composite were compared to those of the nonreinforced cordierite matrix. As would be expected, the whisker- reinforced matrix showed a significant improvement in mechanical properties.

The specimens used for testing were processed by hot-pressing in an argon atmosphere using a graphite die coated with boron nitride. Hot pressing was carried out at 950°C for the pure matrix …

A Study Of High Temperature Oxidation Resistance Of Plasma Treated Nb-Ti-Al Alloys, Roderick R. Rowland

Opportunities for Undergraduate Research Experience Program (OURE)

The effect of plasma treatment on the oxidation behavior of Ti-22Al-27Nb (atomic%) has been studied. The alloy, cast as an ingot by triple VAR and worked to a billet, was cut into smaller samples and oxidation plasma pre-treated. Oxidation plasma pre-treatments were conducted at four ambient temperatures: 25°C, 200°C, 400°C, and 500°C. Both the untreated and plasma pre-treated samples were oxidized at 700°C and 1000°C for one hour, in a muffle furnace. The oxidation behavior of the samples led us to do an extended oxidation of 100 hours at 700°C. The 200°C plasma pre-treated samples showed a definite leveling out …

Influence Of Pattern Geometry And Pouring Temperature On Fluidity In The Expendable Pattern Casting Process, Diego Rodriguez Risco

Opportunities for Undergraduate Research Experience Program (OURE)

This report is an extension of the paper "Influence of Pattern Geometry and other Process Parameters on Mold Filling in the Aluminum EPC Process", by Yuan Sun, Hai-Lung Tsai and Donald R. Askeland (2). The increase in fluidity in the expendable pattern casting (EPC) process with pattern perimeter, volume to surface area (V/A) ratio, and pouring temperature was studied for a 700°C-900°C temperature range and for both aluminum and cast iron.

Solidification Modeling Of Centrifugal Casting, Stephen M. Lane

Opportunities for Undergraduate Research Experience Program (OURE)

This paper describes the methodology used to estimate the solidification time of castings produced by processes in which normal thermal analysis cannot be used, such as centrifugal casting. This methodology utilizes the relationship between microstructure, in particular secondary dendrite arm spacing (SDAS), and freezing time. Using this method it is shown that position within the casting and casting geometry affect the SDAS and freezing time. However, the SDAS did not vary across the wall section due to differences in filling pattern compared to sand casting. Further research is necessary to determine filling pattern effects on microstructure.

Electrochemical Technique For Evaluating Surface Area Of A Treated Copper Foil, Gregory Lea

Opportunities for Undergraduate Research Experience Program (OURE)

In order to increase the strength of copper foil bonded to a polymeric substrate material, a dendritic layer is electrodeposited onto the foil. Treating the foil in this manner causes its surface to be rough and porous, thus providing for better penetration of the adhesive and a greater surface area for bonding. The process is particularly helpful in the manufacturing of printed circuit cards, due to the added bond strength which greatly enhances the durability of the printed circuit cards.

Tape Casting For Lead Zirconate Titanate (Pzt) Multilayer Composites, Jane L. Cochran

Opportunities for Undergraduate Research Experience Program (OURE)

Tape casting is a process for making thin flat ceramic pieces by using a scraping blade or "doctor blade" to evenly coat a smooth surface with a slip[ 1 ]. The slip is a mixture of powder, solvent, binder, and other organics which result in a paint like consistency after they are mixed.

The tapes is cast into thicknesses ranging from 1 to 50 mils on a smooth surface , which is usually made of Mylar, and left to dry.

Once the tape has dried it can be cut into several different shapes and sizes, and then fired to form …

Lrfd For Engineered Wood Structures - Connection Behavioral Equations, Thomas E. Mclain, Lawrence A. Soltis, David Pollock, Thomas L. Wilkinson

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A new design specification for engineered wood structures has been proposed in load and resistance factor design (LRFD) format. This paper provides an overview of the proposed LRFD connections design criteria. The connections design provisions are, in part, calibrated from allowable stress design provisions. Major changes from historic practice, however, result from a change in behavioral equations to a theoretical base for predicting the lateral strength of connections using bolts, screws, and nails. New provisions for axial withdrawal of driven and turned fasteners, as well as combined axial and lateral loading criteria are also proposed. Safety levels were calibrated to …

The Influence Of Matrix Microstructure, G. M. Vyletel, J. E. Allison, David C. Van Aken

Materials Science and Engineering Faculty Research & Creative Works

The low-cycle and high-cycle fatigue behavior and cyclic response of naturally aged and artificially aged 2219/TiC/15p and unreinforced 2219 Al were investigated utilizing plastic strain-controlled and stress-controlled testing. The cyclic response of both the reinforced and un-reinforced materials was similar for all plastic strain amplitudes tested except that the saturation stress level for the composite was always greater than that of the unreinforced material. The cyclic response of the naturally aged materials exhibited cyclic hardening and, in some cases, cyclic softening, while the cyclic response for the artificially aged materials showed no evidence of either cyclic hardening or softening. The …

Defect Structure Of Y1-Ycaymno3 And La1-Ycaymno3. I. Electrical Properties, J. W. Stevenson, M. M. Nasrallah, Harlan U. Anderson, Don M. Sparlin

Materials Science and Engineering Faculty Research & Creative Works

Electrical conductivity and the Seebeck coefficient of compositions in the system Y_1-yCa_yMnO₃ and La_1-yCa_yMnO₃ were studied to determine the mechanism of electrical transport and defect structure. Electrical conduction appeared to occur via a small polaron hopping mechanism for compositions with 0.30 ≤ y ≤ 0.80. The Seebeck coefficient data did not support the assumption that Mn is present in Cadoped Mn perovskites only in the +3 and +4 valence states. A new defect model was developed which includes the thermally excited disproportion of Mn³⁺ and Mn⁴⁺ pairs. The …

Glow-Discharge Enhanced Permeation Of Oxygen Through Silver, D. Wu, R. A. Outlaw, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The permeation of oxygen through Ag0.05Zr over the temperature range of 300-650°C under glow-discharge conditions has been studied and compared to the permeation of thermally dissociated molecular oxygen. A low-energy dc glow-discharge in O₂ has been employed which produced approximately 10% atoms. The permeation rate during the glow discharge was found to be much higher (a factor of ∼10) than without the glow discharge. The small fraction of oxygen atoms generated appears to dominate the permeation because of much higher solution probabilities. Below 500°C, the activation energy for the permeation with glow discharge was found to be 15.5 kcal/mol …

Superheating Of Bi(0001), E. A. Murphy, H. E. Elsayed-Ali, J. W. Herman

Electrical & Computer Engineering Faculty Publications

Superheating of Bi(0001) by about 90 K above the bulk melting temperature is observed using time-resolved reflection high-energy electron diffraction with ∼200-ps time resolution. Larger temperature excursions above the bulk melting temperature result in melting accompanied by irreversible laser damage to the surface. The rhombohedral structure of Bi leads to very different behavior of material parameters upon melting as compared with fcc metals. Therefore, our observation of the superheating of Bi(0001), together with the previously observed superheating of Pb(111), suggests the generality of the superheating phenomenon.

Elastic Impact Of Beams On Gap-Spring Supports, Hany Aly Abdelhafiz

Archived Theses and Dissertations

No abstract provided.