Engineering Commons^™

Finite Element Analysis Of Structures With Constrained Viscoelastic Layer Damping, Yung Chen

Mechanical & Aerospace Engineering Theses & Dissertations

It has been demonstrated that constrained viscoelastic layer damping treatments provide an effective means of passive control for structural vibration. These treatments dissipate vibrational energy by inducing shear strain in a thin layer of viscoelastic material. Our interest is in adding passive damping to a structure as an augmentation to active control. For such applications it is desirable to achieve high damping performance in a given frequency range with a minimum of added weight. Most damping treatments employ spatially continuous constraining layers over the entire viscoelastic layer. Plunkett and Lee have shown that the effectiveness of the damping treatment can …

An Expert System For Underground Water Piping Material Selection, Amal Esawi

Archived Theses and Dissertations

No abstract provided.

Knowledge Based Expert System For Flexible Pavement Design In Egypt, Magdy Youssef Mikhail

Archived Theses and Dissertations

No abstract provided.

An Expert System For Underground Under Gravity Sewer Piping Material Selection, Nader Wahib Morcos

Archived Theses and Dissertations

No abstract provided.

Finite Element Evaluation Of The Elastic-Plastic Fracture Parameters, Ibrahim Medhat Ibrahim Ayoub

Archived Theses and Dissertations

No abstract provided.

A Systematic Procedure For The Analysis And Design Of Deployable Space Structures, Praveen Kumar

Mechanical & Aerospace Engineering Theses & Dissertations

An integrated graph theory and a symmetry-based approach have been developed for the type synthesis of deployable truss structures. Using this systematic approach, a bay of a deployable structure may be looked upon as being built around an axis or a plane of symmetry, including anti-symmetry. By providing a fictitious joint along this axis, the problem of structural design and analysis can be reduced to the study of one plane or face of the given structure. Each face is considered to be an assemblage of structural links connected by joints which form a closed kinematic chain. The conventional graph representation …

Electrochemical Evaluation Of Copper Deposition With Gas Sparging, D. A. Uceda, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The influence of gas sparging during copper electrolysis was studied using standard electrochemical techniques. The polarization behavior of acid copper electrolytes was determined in the presence and absence of gas sparging on vertical electrodes. Tracer ion techniques were employed to determine the effect of gas sparging and forced circulation of the electrolyte on the mass transfer characteristics of the system. In addition to the potentiodynamic scans, 3-h copper deposits were produced for morphology and orientation studies. The effect of current density and temperature on deposition were also studied. The polarization experiments have shown that a mass transfer component becomes evident …

The Effects Of Lead On The Electrochemical And Adhesion Behavior Of Zinc Electrodeposits, Vijay Srinivasan, J. Sami Cuzmar, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The presence of excessive lead in zinc sulfate electrolytes can lead to problems related to both processing efficiency and the properties of the metal produced. For example, poor adhesion can occur in electrogalvanized steel when it is heated in the temperature range of 215 °C to 280 °C if lead is present in the deposit. The duration of heating necessary to induce the peeling of the zinc was found to be dependent on the temperature, time, and concentration of lead in the electrolyte and the plating parameters. The presence of lead slowed the formation of the intermetallic, and the peeling …

Oxidation-Reduction Behavior Of Undoped And Sr-Doped Lamno3: Defect Structure, Electrical Conductivity, And Thermoelectric Power, J. H. Kuo, Harlan U. Anderson, Don M. Sparlin

Materials Science and Engineering Faculty Research & Creative Works

Seebeck coefficient and electrical conductivity measurements were performed for undoped and Sr-doped LaMnO₃ as a function of temperature and oxygen partial pressure. The results of electrical conductivity showed typical p-type behavior. As reduction proceeded, the electrical conductivity of these LaMnO₃-based perovskites decreased with P 1 4O₂. The analysis of the electrical conductivity data was performed by extending the defect model from a previous thermogravimetric (TG) study. The measured Seebeck coefficients were found to be positive except for the most reducing conditions when the decomposition into multiple phases occurred. The Heikes formula was adopted to interpret …

Design Considerations For 1-3 Composites Used In Transducers For Medical Ultrasonic Imaging, Wayne Huebner, Kuiming Liang, Clyde G. Oakley

Materials Science and Engineering Faculty Research & Creative Works

Ceramic polymer piezoelectric composites with 1-3 connectivity have become an important tool in the design and manufacture of thickness-mode transducers for medical diagnostic ultrasonic imaging. The authors compare annular array transducers made from ceramics alone to those made with these composites to demonstrate the advantages of composites. They examine some of the trade-offs involved in optimizing composite designs for this application. The effects of varying Young's modulus and Poisson's ratio of the polymer phase on the coupling coefficient and high-frequency lateral resonances of the composite are presented

Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola

Electrical & Computer Engineering Faculty Publications

The influence of the copper concentration in silicon-doped gallium arsenide on the photoionization and photoquenching of charge carriers was studied both experimentally and theoretically. The studies indicate that the compensation ratio (N_Cu/N_Si) is an important parameter for the GaAs:Si:Cu switch systems with regard to the turn-on and turn-off performance. The optimum copper concentration for the use of GaAs:Si:Cu as an optically controlled closing and opening switch is determined.

Microstructural Characterization Of Rapidly Solidified And Extruded Ti-Al-Nb Alloys, Danny Joe Edwards

Masters Theses

"Two titanium alloys have been characterized using transmission and scanning electron microscopy, X-ray diffraction, and optical metallography techniques. Both of these alloys were rapidly solidified by melt spinning, the resulting ribbons pulverized, and the powders then extruded into cylindrical billets. The alloys are based on the compositions Ti-21.3Al- 9 Nb-0.6-Mo-2.6V and Ti-13.2Al-2.6Nb-0.5Mo-0.9V-0.5Zr-3.1B in atomic percent. The first alloy was examined in both the as-extruded condition and in the annealed condition (looo0c for 12 hours). The second alloy was examined in the as-extruded condition only.

For the first alloy, the as-extruded microstructure consisted of a B2 matrix with alpha-2 particles at …

Fluid Dynamics Of An Atomizer Nozzle, Bhaskar Sengupta

Masters Theses

"A pilot plant gas atomizer was designed and assembled at the Center of Pyrometallurgy, U.M.R., to produce metal powders. The pilot plant utilizes a confined, annular, supersonic nozzle to yield spherical metal powders (aluminum and zinc alloys have been atomized) of average size of 15μm in diameter.

A cold model of the atomizing nozzle was constructed to simulate the pilot plant. First, the high-speed gas flow was studied and later, modelling of the atomizing process was carried out by using water as the atomized liquid. This work has investigated the complex gas flow in the converging-diverging nozzle and around the …

Comments On The Papers By Kê And Su, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Production Of Thin Copper Foils On Microporous Titanium Oxide Substrates, J. L. Delplancke, M. Sun, Thomas J. O'Keefe, R. Winand

Materials Science and Engineering Faculty Research & Creative Works

This study deals with the electrochemical production of thin (35 μm) copper films on anodized titanium substrates. The formation of a microporous oxide layer on the titanium electrodes greatly enhances the surface density of copper nuclei during a potentiostatic experiment so that a complete coverage of the cathode surfaces may be obtained after short term (20 s) polarization. Moreover, the oxide film may act as a parting agent and the copper films may be easily stripped from their substrates. The higher the pore density of the oxide film, the higher the surface density of nuclei and the easier the foil's …

Mass-Transfer Measurements Of Copper Deposition In A Fluosilicate Electrolyte, D. Uceda, Thomas J. O'Keefe, E. Cole

Materials Science and Engineering Faculty Research & Creative Works

The electrodeposition of copper from a fluosilicate electrolyte has been investigated by electrochemical techniques, x-ray diffraction, and scanning electron microscopy. The diffusion coefficient of cupric ion in a fluosilicate solution has been determined with the aid of a rotating disk electrode using the mixed control Levich equation. Gold (Au⁺³) was used as a tracer to evaluate the mass transport properties of the system. The polarization behavior of the electrolyte was measured in the presence and absence of gas sparging on a vertical stationary electrode to study the effect of the mass transport contribution. Sound copper deposits were obtained …

Composition And Method For Radiation Synovectomy Of Arthritic Joints, D. E. Day, Gary J. Ehrhardt

Materials Science and Engineering Faculty Research & Creative Works

Radioactive microspheres for radiation synovectomy of arithmetic joints in a mammal comprise a biodegradable glass material and a beta radiation emitting radioisotope chemically dissolved in and distributed substantially uniformly throughout the glass material. The biodegradable glass material may be lithium silicate, lithium aluminosilicate, lithium aluminoborate, lithium germa- nate, lithium aluminogermanate, potassium silicate, potassium aluminosilicate, potassium, aluminoborate, potassium germanate or potassium aluminogermanate and the beta radiation emitting radioisotope may be samarium-153, holmium-166, erbium-169, dysprosium-165, rhenium-186, rhenium-188 or yttrium-90. Methods for preparing such microspheres and for carrying out radiation synovectomy of arthritic joints utilizing such microspheres are also disclosed.

Structural Characteristics Of Sr1-Xlaxti 3+Δ As A Function Of Oxygen Partial Pressure At 1400°C, S. A. Howard, J. K. Yau, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The structural characteristics of Sr_1-x La_x TiO_3+δ (0≤x≤0.4) at 1400°C have been investigated as a function of ambient oxygen partial pressure. A modified Rietveld pattern-fitting structure-refinement program [H. M. Rietveld, J. Appl. Crystallogr. 2, 65 (1969)] was used to determine the nature of the distortions of the fundamental perovskite unit cell, the degree of lattice perfection, and the cation vacancy concentrations. Specimens equilibrated in forming gas displayed a linear relation between x, the lattice parameters, and the degree of lattice perfection while those samples annealed in air and oxygen deviated significantly from linearity. A monoclinic distortion of …

Aluminum Deposition On Polyimides: The Effect Of In Situ Ion Bombardment, M. J. Vasile, Bonnie Bachman

Economics Faculty Research & Creative Works

The chemistry of the Al polyimide interface is examined by x‐ray photoelectron spectroscopy sputter profiling. Al deposited on polyimide films without an in situ Ar backsputter shows a clearly defined 50‐Å Al₂O₃ layer just prior to the polyimide. This layer is identified by the O/Al atom ratio at 1.5, and the binding energy of the Al 2p transition. There is a clear separation of the Al/Al₂O₃/polyimide layers in the sputter profiles. Deposition of Al on polyimide surfaces after Argon backsputtering produces a diffuse Al/polyimide interface with no Al₂O₃ present. There …

31st Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Program and registration information for the 31st annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, July 30 - August 4, 1989.

Determinations Of Molecular Weight And Molecular Weight Distribution Of High Polymers By The Rheological Properties, Joan Y. Z. Huang

Mechanical & Aerospace Engineering Theses & Dissertations

Several methods are reviewed by which the molecular weight (MW) and molecular weight distribution (MWD) of polymeric material were determined from the rheological properties. A poly (arylene ether) polymer with six different molecular weights was used in this investigation. Experimentally measured MW and MWD were conducted by GPC/LALLS (Gel Permeation Chromatography/Low Angle Laser Light Scattering), and the rheological properties of the melts were measured by a Rheometric System Four rheometer. It was found that qualitative information of the MW and MWD of these polymers could be derived from the viscoelastic properties, with the methods proposed by Zeichner and Pate1, and …

Stability Design Of A Slender Column With Curved Longitudinal Stiffeners, Mark S. Lake

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis presents the results of a stability design study of a slender column with curved longitudinal stiffeners for large space structure applications. The stiffened column concept is attractive because it allows the buckling load of a slender column to be increased at a fairly low cost in increased mass, and at no change in the column packaged size. Linear stability analyses are performed using a "linked-plate" representation of the stiffeners to determine stiffener local buckling stresses. Results from a set of parametric analyses are used to determine an approximate explicit expression for stiffener local buckling in terms of its …

Ion Bombardment Of Polyimide Films, Bonnie Bachman, M. J. Vasile

Economics Faculty Research & Creative Works

Surface modification techniques such as wet chemical etching, oxidizing flames, and plasma treatments (inert ion sputtering and reactive ion etching) have been used to change the surface chemistry of polymers and improve adhesion. With an increase in the use of polyimides for microelectronic applications, the technique of ion sputtering to enhance polymer‐to‐metal adhesion is receiving increased attention. For this study, the argon‐ion bombardment surfaces of pyromellitic dianhydride and oxydianiline (PMDA–ODA) and biphenyl tetracarboxylic dianhydride and phenylene diamine (BPDA–PDA) polyimide films were characterized with x‐ray photoelectron spectroscopy (XPS) as a function of ion dose. Graphite and high‐density polyethylene were also examined …

Carrying Capacity And Cracking Resistance At The Support Zone Of Halving Joints In Reinforced Concrete Beams, H. W. Chung

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Carrying Capacity And Cracking Resistance Of The Bracket, S. Mpinzire

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Pile Driving Analysis In Selected Egyptian Soil Deposits, Yasser Abd Elhamid Gowayed

Archived Theses and Dissertations

No abstract provided.

Characterization Of Zirconia Gels And Their Selectivity Towards Metal Ions, Manal Mohamed Talaat El- Saidi

Archived Theses and Dissertations

No abstract provided.

Reagents For Magnetizing Nonmagnetic Materials, Jiann-Yang Hwang

Michigan Tech Patents

Particles of a nonmagnetic material are rendered magnetic by contacting their surfaces with a magnetizing reagent comprising water containing particles of a magnetic material, each of which has a two layer surfactant coating including an inner layer and an outer layer. The inner layer covers the magnetic particle and is a mono- molecular layer of a first water soluble, organic, hetero- polar surfactant containing at least 3 carbon atoms and having a functional group on one end which bonds with the magnetic particle. The outer layer coats the inner layer and is a monomolecular layer of a second water soluble, …

Evaluation Of Mass Transport In Copper And Zinc Electrodeposition Using Tracer Methods, H. M. Wang, S. F. Chen, Thomas J. O'Keefe, M. Degrez, R. Winand

Materials Science and Engineering Faculty Research & Creative Works

Control of the electro crystallization process is essential in the deposition of metals from aqueous electrolytes. A knowledge of the influence of mass transfer on the metal ion reduction is a critical element in any number of electrolytic processes, particularly where relatively high current densities are desired. The use of more positive ion tracer techniques as a means of experimentally determining some of the mass transport properties of interest are described. Examples for copper, zinc and zinc alloys electrolysis are included. © 1989 Chapman and Hall Ltd.

Using Living Materials To Intervene In The Natural Succession Process To Accelerate The Re-Development Of A Self-Sustaining Ecosystem That Has Been Damaged By Human Intervention, Eric Jorgensen

Materials Engineering

No abstract provided.