Engineering Commons^™

Two Methods For Attenuation Of Vibration In Structures, Kevin Mark Mcclendon

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this report is to discuss methods of suppressing vibration in space trusses. The discussion is centered on the approach, structural attributes, and effectiveness of each method. One approach uses structural active members which are actuated to produce “anti-vibration” to cancel vibrations in the truss. The other method is to implement passive and active damping devices at the base of the space truss, where it will absorb vibrations by fluctuating the stiffness of the structures foundation.

Gamma Dose To A Fetus From Internal And External Sources, Lisa Stiles

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this study was to use the QAD computer code to calculate the dose received by a fetus from external and internal sources to which the mother is exposed. The changes in Chapter 10, part 20 of the Code of Federal Regulations that will be put into effect January 1, 1994, will require that radiation doses be reported not only for the whole body but to specific organs and the fetus as well. Fortunately, the computer program QAD can provide health physicists and other persons responsible for monitoring radiation exposure of individuals with an accurate, easy to use …

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 …

Using Modulated Beam Mass Spectrometry Techniques To Determine Hydrogen Levels In Single Crystal And Etched Single Crystal Silicon, Gregory J. Teets

Opportunities for Undergraduate Research Experience Program (OURE)

Silicon is an important element that has many applications ranging from semiconductors to solar cells. The quantity, diffusion, and bonding of hydrogen atoms in the silicon can play an important role in the electrical characteristics of single crystal and etched single crystal silicon. The hydrogen bonds to the impurities and to the dangling bonds in the silicon and reduces current leakage and improves performance [1-4]. Until now hydrogen bonding data has been extrapolated from related studies to determine hydrogen evolution temperatures from the silicon. Abrefah, Olander, et al. [1] studied deuterium evolution from silicon where the deuterium had been implanted …

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.

Damage Assessment Of Composite Structures With Embedded Optical Fibers, Peter E. Hackett

Opportunities for Undergraduate Research Experience Program (OURE)

One of the important features of smart composite structures is their capability to observe their own performance for proper functioning and self-diagnostic purposes. The low velocity impact damage of composite structures (matrix cracking, fiber breakage, delamination, etc.) is often difficult to detect visually and can significantly reduce the strength of the structure. The objective of this research is to develop a technique for fabricating composite laminates that will facilitate the embedment of optical fibers. Composite test specimens will be fabricated in the composite material laboratory. The fabrication of composite laminates with a health monitoring and damage assessment system capable of …

Active Buckling Control Of Composite Plates, Bradley Wayne Gentelin

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of the research project is to investigate the feasibility of using the rapidly growing technology of smart materials in actively controlling the buckling of laminated composite plates. Advanced composite structures are susceptible to structural instabilities under compression loadings, and the proper control of such instabilities is essential to the effective performance of the structures. The focus of the research activity is to perform an experimental study of using embedded piezoelectric materials for enhancing the critical buckling loads of laminated composite plates. The forces induced by the piezoelectric actuators under the applied voltage fields will be used to counterbalance …

Fiber Optic Fabry-Perot Sensors For Smart Structures, Thomas K. Edmondson

Opportunities for Undergraduate Research Experience Program (OURE)

Optical fiber sensors promise to play a large role in the development of smart structures which have the ability to continuously monitor themselves for internal and external structural deformation, and even actively change shape. This investigation studies one such sensor based on a fiber optic Fabry-Perot interferometer, which detects the displacement between two points of a material. Sensor theory and construction are discussed, and the tools used to analyze sensor output are developed. The interferometer is then tested by attaching it to a large cantilever beam which is deflected to produce strain. This experimental data is then used to determine …

Aerodynamics Of Solar Vehicles, Richard R. Pardun

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this research project is to design the shape of a fully road worthy vehicle operating under nothing but the power of the sun. This vehicle was to meet all racing regulations of The Sunrayce and the World Solar Challenge. Because of the specific use of this vehicle, this project provides a chance to explore the aerodynamically ideal vehicle. Little attention has to be paid to practicality. The result is a very streamlined, highly aerodynamically efficient car, that is still stable and safe.

Analysis Of Turnability For A Three Terminal Microwave Network, Michael J. Bahr

Opportunities for Undergraduate Research Experience Program (OURE)

Three-terminal microwave networks can be shown to exhibit qualities that would make them desirable to be used as multiple terminal devices. Using microwave theory, where instantaneous voltage is a function of position on the line, this situation will be examined. These devices use the interference principle of propagating waves as the basis of their characteristics. This investigation will probe a three- terminal microwave network with one input and two output. This configuration acts similar to a splitter where the outputs may be controlled. These three terminals, plus manipulation of the lengths of each side, actually makes this a four terminal …

Fiber Optic Microdeformation Sensors For Smart Structures, Lawrence S. Criscione

Opportunities for Undergraduate Research Experience Program (OURE)

When optical fibers are stressed, the deformations at the core-cladding interface induce signal attenuation. Because of their durable physical properties (high melting point) optical fibers can be embedded into certain composite materials at the manufacturing stage. Stresses on the composite induces stresses on the embedded fiber. The amount of stress on the fiber, and thus the stress on the composite, can be determined by measuring the attenuation of a signal passing through the fiber. Force was applied to a single mode and a multimode fiber in a microbend inducing plate, and the attenuation this stress created was measured.

Analysis Of A Thrust Vectoring Fighter Aircraft Using Realtime Flight Simulation, Clinton A. Thessen

Opportunities for Undergraduate Research Experience Program (OURE)

A real-time flight simulation model based on the McDonnell Douglas F/A-18 Hornet was created. This model was then modified with two different styles of thrust vectoring so that a study of each system's effect on the aircraft's pitch performance could be conducted in order to determine the best system. At present, work is proceeding on the development of active flight controls for the aircraft. After that effort is completed the thrust vectoring study can begin.

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 …

Catalysis Of Charcoal Emissions, James M. Horak

Opportunities for Undergraduate Research Experience Program (OURE)

This paper is about the development of a system to reduce the emissions of charcoal kilns with the catalyst from automotive catalytic converters. This device, called the charcoal kiln emissions oxidizer (CKEO), was designed and fabricated to meet the goal of a cost effective means to reduce the carbon monoxide and hydrocarbon emissions from charcoal kilns. Testing of the CKEO was never carried out as a test site could not be secured by this writing. The need for the CKEO, the theory behind it, and a procedure to test it are presented.

Flexural Behavior Of Web Elements With Openings, Roger A. Laboube, Wei-Wen Yu, Ming-Yang Shan

CCFSS Library (1939 - present)

No abstract provided.

Simulation De L'Interaction Entre Le Voilement Local Et Les Modes Globaux D'Instabilite Des Profils A Froid Par Une Combinaison De La Methode Des Largeurs Effectives Et De L'Element Fini Non-Lineaire De Poutre Spatiale, Luiz Felippe Estrella Jr.

CCFSS Library (1939 - present)

The objective of this thesis is the study of the stability of cold-formed thin-walled steel members. The interaction between global instability and local buckling of the profile walls has a reducing effect on the collapse load. The aim is to develop a numerical tool able to predict not only the collapse load, but also the equilibrium path. With this aim in view, the non-linear spatial beam tinite element recently developed by Vincent de Ville in Liege University was chosen for this purpose. The steel member is considered as an association of flat plates and corners. Local buckling is modeled by …

Structural Behavior Of Architectural Laminated Glass, R. A. Belir, Joseph E. Minor, H. S. Norville

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Experimental and theoretical investigations conducted over a 20-year time period by several investigators provide sufficient data and information to define, for practical engineering purposes, the behavior of architectural laminated glass under lateral pressures. Investigations included definitions of material properties, theoretical stress analyses, experimental stress analyses, and destructive tests involving monolithic, laminated, and "layered" glass plates of several geometries. The preponderance of data and information indicate that: (1) Architectural laminated glass behaves in a manner similar to monolithic glass of the same nominal thickness under short-term lateral pressures (representative of wind loads) at and below room temperature; (2) the temperature at …

Phenotypic Characterization Of Copper-Resistant Mutants Of Methylosinus Trichosporium Ob3b, M. (Mark) W. Fitch, D. W. Graham, R. G. Arnold, S. K. Agarwal, P. Phelps, G. E. Speitel, G. Georgiou

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Cultures of Methylosinus Trichosporium OB3b Grown in the Presence of Very Low Concentrations of Copper Synthesize a Soluble Methane Monooxygenase (SMMO) that Efficiently Catalyzes the Oxidation of Trichloroethylene and Other Organic Pollutants. Recently, We Isolated Five M. Trichosporium OB3b Mutants that Express SMMO Activity When Grown in the Presence of Elevated Copper Concentrations (P. A. Phelps, S. K. Agarwal, G. E. Speitel, Jr., and G. Georgiou, Appl. Environ. Microbiol. 58:3701-3708, 1992). Here We Show that, in Contrast to the Results for the Wild-Type Cells, the Addition of Copper to Mutant Cultures Grown on Methane and Nitrate as the Nitrogen Source …

Assessment Of Environmental Implications Of Abandoned Oil And Gas Wells, Donald L. Warner, Cary L. Mcconnell

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A detailed study was made of the potential for abandoned oil and gas wells in the Lower Tuscaloosa sand of Mississippi and Louisiana to act as conduits for movement of saline water from the Lower Tuscaloosa into underground sources of drinking water (USDW's). Finite-difference numerical modeling determined the extent that water might be forced from the Lower Tuscaloosa sand into a USDW as a result of injection into the Lower Tuscaloosa. Within the range of conditions modeled, water from the Lower Tuscaloosa never traveled into a USDW. On the basis of the modeling, we concluded that it is unlikely that …

Blast Plug And Stemming Construction For Blast Holes, Paul Nicholas Worsey

Mining Engineering Faculty Research & Creative Works

A plug for use in stemming a blast hole having an explosive charge therein. The plug comprises a wedge member and a stabilizing structure on the wedge member. The wedge member tapers in an outward direction from a relatively wide base to a relatively narrow end and has a central axis extending endwise with respect to the wedge member. The stabilizing structure extends generally axially with respect to the wedge member from adjacent the base of the wedge member. The plug is to be positioned in the blast hole with the base of the wedge member facing inwardly toward the …

Postbuckling And Hysteresis Models Of Open-Web Girders, Jeng Fuh Ger, Franklin Y. Cheng

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The paper presents analytical studies of hysteretic behavior of open-web girders with angle web members. The partial inelasticity of the member cross section is traced using finite segment formulation with stress-strain control. A member is divided into a number of segments, and, for each segment, the cross section is divided into many small elements, which allows the inelastic deformation of the member to be modeled. Therefore, member stiffness is established for various inelastic deformation stages. The eccentricities and initial imperfections of web members are considered in the analysis. Good agreement between experimental and present analytical results was found for individual …

Behavior Of Arc Spot Weld Connections In Tension, Roger A. Laboube, Wei-Wen Yu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Arc spot welds, commonly called puddle welds, are widely used for connecting cold-formed steel roof decks to their supporting members. These support members are typically hot-rolled steel beams or girders, or the top chord of open-web steel joists. A comprehensive experimental study of the tension strength of arc spot weld connections used to affix a cold-formed steel roof deck to its support member was conducted. The study investigated the key parameters that influence the connection strength: Steel thickness, tensile strength, and ductility; type of weld process, automatic or manual; cross section of the roof deck; loading condition, symmetrical or eccentric …

Analytical Guidance Laws And Integrated Guidance/Autopilot For Homing Missiles, S. N. Balakrishnan, Donald T. Stansbery, J. H. Evers, J. R. Cloutier

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approach to integrated guidance/autopilot design is considered in this study. It consists of two parts: 1) recognizing the importance of polar coordinates to describe the end game in terms of problem description and measurement acquisition, the terminal guidance problem is formulated in terms of polar coordinates; 2a) through the use of the state transition matrix of the intercept dynamics, a closed form solution for the transverse command acceleration is obtained; and 2b) through a commonly used approximation on time-to-go and a coordinate transformation, a family of proportional navigation optimal guidance laws is obtained in a closed form. A typical …

Dual Purpose Fuze, Paul Nicholas Worsey

Mining Engineering Faculty Research & Creative Works

A dual purpose fuze for a projectile which can activate a quantity of material selected from a group including high explosive, low explosive, propellant and pyrotechnic compounds. The fuze includes a charge holder having a socket therein facing the quantity of material to be activated. A fuze charge located in the socket has a depression in it so formed as to cause the fuze charge to explode in a jet directed outwardly from the socket of sufficiently high energy to activate a high explosive in a high explosive projectile, the fuze charge being sufficiently small to prevent rupture of containment …

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 …

Mineralization And Uptake Of Triazine Pesticide In Soil-Plant Systems, Dhileepan R. Nair, Joel G. (Gerard) Burken, Louis A. Licht, Jerald L. Schnoor

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Deep-Rooted Trees Planted as a Buffer Zone Can Intercept Runoff and Eroded Sediments, Thus Reducing Non-Point-Source Pollution Due to Agricultural Chemicals. in This Study, Populus Sp. Were Grown in Bioreactors with an Agricultural Soil (Silt-Loam) and in a Silica-Sand Media; Both Were Spiked with ¹⁴C Uniformly Ring-Labeled Atrazine. the Plants Took Up over 11% of the ¹⁴C Labeled Atrazine Applied to the Silt-Loam Soil and over 91% of that Applied to the Silica Sand Media, with the Majority of the ¹⁴C Accumulating as Nonphytotoxic Metabolites in the Leaves. Research Suggests that, in Addition to Nutrient Uptake, Poplar …

Computed Versus Observed Inelastic Seismic Low-Rise Rc Shear Walls, Franklin Y. Cheng, G. E. Mertz, M. S. Sheu, J. F. Ger

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A technique of calculating inelastic deformation of low-rise shear walls having height-width ratios of 0.5 and 0.75 without boundary elements is presented with consideration of the coupling effect for bending and shear deformations as well as the deformation due to base rotation. An interaction surface of moment, shear, and curvature or moment, shear, and shear strain is developed. The deflections at crack, yield, and ultimate loadings can be calculated separately from bending and shear deformations, which are compared favorably with experimental results. The shear deformation is significant for the low-rise walls studied because the deformation due to bending deformation is …