Mechanical Engineering Commons^™

Process For The Formation Of Wear- And Scuff-Resistant Carbon Coatings, Gerard W. Malaczynski, Xiaohong Qiu, Joseph V. Mantese, Alaa A. Elmoursi, Aboud H. Hamdi, Blake P. Wood, Kevin C. Walter, Michael Nastasi

Department of Mechanical and Materials Engineering: Faculty Publications

A process for forming an adherent diamond-like carbon coating on a workpiece of suitable material such as an aluminum alloy is disclosed. The workpiece is successively immersed in different plasma atmospheres and subjected to short duration, high voltage, negative electrical potential pulses or constant negative electrical potentials or the like so as to clean the surface of oxygen atoms, implant carbon atoms into the surface of the alloy to form carbide com pounds while codepositing a carbonaceous layer on the surface, bombard and remove the carbonaceous layer, and to thereafter deposit a generally amorphous hydrogen-containing carbon layer on the surface …

Buckling Analysis And Optimum Design Of Multidirectionally Stiffened Composite Curved Panel, Navin R. R. Jaunky

Mechanical & Aerospace Engineering Theses & Dissertations

Continuous filament grid-stiffened structure is a stiffening concept that combines structural efficiency and damage tolerance. However, buckle resistant design optimization of such structures using a finite element method is expensive and time consuming due to the number of design parameters that can be varied. An analytical optimization procedure which is simple, efficient and supports the preliminary design of grid-stiffened structures for application to combined loading cases is needed.

An analytical model for a general grid-stiffened curved panel is developed using an improved smeared theory with a first-order, shear-deformation theory to account for transverse shear flexibilities and local skin-stiffener interaction effects. …

An Experimental Investigation Of Wall Cooling Effects On Hypersonic Boundary Layer Stability In A Quiet Wind Tunnel, Alan E. Blanchard

Mechanical & Aerospace Engineering Theses & Dissertations

One of the primary reasons for developing quiet tunnels is for the investigation of high-speed boundary-layer stability and transition phenomena without the transition-promoting effects of acoustic radiation from tunnel walls. In this experiment, a flared-cone model under adiabatic- and cooled-wall conditions was placed in a calibrated, 'quiet' Mach 6 flow and the stability of the boundary layer was investigated using a prototype constant-voltage anemometer. The results were compared with linear-stability theory predictions and good agreement was found in the prediction of second-mode frequencies and growth. In addition, the same 'N=10' criterion used to predict boundary-layer transition in subsonic, transonic, and …

Indoor Air Quality Impacts Of Uncontrolled Air Flow And Depressurization In Eight Commercial Buildings In Central Florida, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Field investigations were done in 68 commercial buildings to identify uncontrolled air flows and pressure imbalances. Results from eight buildings (six restaurants and two sports facilities) are reported in this paper. Testing included building airtightness tests, identification of building air barrier location, duct system airtightness, characterization of pressure differentials, building air flow balance, and infiltration/ventilation rates. Six restaurants and one sports facility were found to operate at negative pressures which ranged from -0.003 inWC (-0.8 Pa) to -0.173 inWC (-43 Pa) and averaged -0.051 inWC (-12.7 Pa) under normal operation. A second sports facility operates partially at positive pressure and …

Chp And Energy Conservation, Jim Mcgovern

Articles

The principles of the use of 'combined heat and power' (CHP) for the achievement of fuel energy conservation, minimisation of environmental impact and economic advantage are explained. A distinction is made between the two types of outputs: heat and work. It is argued that an efficiency value that is defined as the sum of the heat and work outputs divided by the energy of the fuel used is not very meaningful. An alternative, rational, efficiency is explained. It is concluded that CHP is an option to be considered where both heating and power are required, but is not a general …

Study Of The Wear Behaviour Of Al-4.5% Cu-3.4% Fe In Situ Composite: Effect Of Thermal And Mechanical Processing

A.S. Md Abdul Haseeb

Wear behaviour of as-cast and heat-treated spheroidal graphite (SG) cast iron has been studied under dry sliding conditions using a pin-on-disc type apparatus. Wear tests were carried out at a linear sliding speed of 0.88 m s -1, under a constant load of 1.5 kg. All tests were performed in ambient air at room temperature. Extent of wear damage and wear mechanisms were investigated by means of weight loss measurement, optical microscopy, microhardness measurement and X-ray diffractometry on wear debris. The wear rate measured after 9500 m of sliding is found to be about three times higher in the as-cast …

Tractor Test Museum Committee Minutes August 11, 1995, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Bid for Roof Replacement National Historic Site Additional Support

Atec: The Aerodyanmic Turbine Engine Code For The Analysis Of Transient And Dynamic Gas Turbine Engine System Operations, Glenn Douglas Garrard

Doctoral Dissertations

A new one-dimensional, time dependent aerothermodynamic mathematical model and computer simulation of the gas turbine engine has been developed and is introduced herein. The Aerodynamic Turbine Engine Code (ATEC) simulates the operation of the gas turbine engine by solving conservation equations, expressed as one dimensional, time dependent Euler equations, with turbomachinery source terms. By incorporating both implicit and explicit equation solvers, transient simulations of the gas turbine engine can be conducted efficiently while maintaining the capability of simulating dynamic events such as compressor stall. ATEC can also be used to address dynamic events or steady-state processes to model both on- …

Window-On-Europe, S. R. Leclair, A. G. Jackson

Mechanical and Materials Engineering Faculty Publications

This report covers a three week visit to the following locations: 1.) A.A. Baikov Institute of Metallurgy of the Russian Academy of Science, Moscow, Russia; 2.) Institute for Applied Informatics, of the Ukrainian Academy of Science, Kiev, Ukraine; 3.)Engineering Design Center.Cambridge University, Cambridge, England- and 4) Artificial Intelligence Department, University of Edinburgh, Edinburgh, Scotland. The visits involved sites whose current research involved either empirical methods for the design of materials and resultant products and/or the development of empirical methods of potential benefit in automating empirical research of materials and/or processing. The report address, for each site, 1) a brief overview …

A Theoretical Nonlinear Dynamical Model Of Coupled Heat And Momentum Transfer In Forced Convection Film Boiling, Jolie Ann Long

All Theses

In film boiling, a layer of vapor completely blankets the heated surface and prevents liquid contact with the surface. Film boiling is usually considered undesirable because it is an inefficient mode of heat transfer and can lead to temperatures in excess of those allowed for many materials. Because film boiling may inhibit desired heat transfer in several processes including metals manufacturing, cryogenic engineering, and electronic cooling, it is useful to consider how the film boiling vapor layer may be destabilized or altered such that time-averaged heat transfer is improved.

An Experimental Study Of The Effects Of Double-Diffusive Convention Processes During The Solification Of Binary Alloys, Richard Burton

FIU Electronic Theses and Dissertations

Experiments were conducted to show the effects of thermal and geometric boundary conditions on the liquid pool of a binary alloy system which is undergoing phase change, solidification. Transparent analogue solutions were selected for study and experimental apparatus were designed and built. Thermal distribution and concentration data were collected and analysed for the melt pool of various selected geometries and boundary conditions of the systems under study. The data indicate-that characteristic flows develop for both Hypereutectic and Hypoeutectic concentration levels and that the development of macrosegregation and microsegregation defects in continuous casting materials can be minimised by the adjustment of …

Method Of Making Quasicrystal Alloy Powder, Protectivecoatings And Articles, Jeffrey E. Shield, Alan I. Goldman, Iver E. Anderson, Timothy W. Ellis, R. William Mccallum, Daniel J. Sordelet

Department of Mechanical and Materials Engineering: Faculty Publications

A method of making quasicrystalline alloy particulates wherein an alloy is superheated and the meltis atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture.

On The Reuse Of Bolts Which Have Been Torqued To Yield, Dal B. Lee, Joseph Foyos, Martin L. Smith, Omar S. Es-Said, Otto Kossuth

Mechanical Engineering Faculty Works

Bolts are torqued to yield in automotive engines to fasten aluminum alloy cylinder heads to cast iron cylinder blocks. This tightening method provides a reliable, even, and controllable clamping force that prevents warping of the soft cylinder head and ensures a leak-tight joint. It has one drawback: Since the bolts yield during engine assembly, they work harden even as their ultimate strength decreases. Upon reuse, yield stress more closely approaches ultimate strength. Fastener geometry and mechanical properties, now changed, supply changed joint-clamping force. For reasons such as these. Ford Motor Company recommends that bolts torqued to yield be replaced each …

Nonlinear Transient Thermal Analysis By The Force-Derivative Method, Narayani V. Balakrishnan

Mechanical & Aerospace Engineering Theses & Dissertations

The force-derivative method (FDM) represents a series of higher-order modal methods which offer an increasingly improved approximation of the higher modes neglected in the basic mode-displacement method (MDM). The FDM includes additional terms which involve the forcing function and derivatives of the forcing function with respect to time. The mode-acceleration method (MAM), extensively used in structural analysis, is a first-order form of the FDM which includes only one correction term that depends on the forcing function itself. The success of the FDM in many structural dynamic applications has prompted its application for solving transient thermal problems. The superior convergence of …

Dynamic Unstructured Method For Prescribed And Aerodynamically Determined Relative Moving Boundary Problems, Kamakhya Prasad Singh

Mechanical & Aerospace Engineering Theses & Dissertations

A new methodology is developed to simulate unsteady flows about prescribed and aerodynamically determined moving boundary problems. The method couples the fluid dynamics and rigid-body dynamics equations to capture the time-dependent interference between stationary and moving boundaries. The unsteady, compressible, inviscid (Euler) equations are solved on dynamic, unstructured grids by an explicit, finite-volume, upwind method. For efficiency, the grid adaptation is performed within a window around the moving object. The Eulerian equations of the rigid-body dynamics are solved by a Runge-Kutta method in a non-inertial frame of reference. The two-dimensional flow solver is validated by computing the flow past a …

Studies Of Mixing Processes In Gases And Effects On Combustion And Stability, Frank Paul Kozusko Jr.

Mathematics & Statistics Theses & Dissertations

Three physical models of laminar mixing of initially separated gases are studied. Two models study the effects of the mixing dynamics on the chemical reactions between the gases. The third model studies the structure and stability of a laminar mixing layer in a binary gas. The three models are:

1. Two ideal and incompressible gases representing fuel and oxidizer are initially at rest and separated across an infinite linear interface in a two dimensional system. Combustion, expected as the gases mix, will lead to a rapid rise in temperature in a localized area, i.e. ignition. The mixing of the gases …

Numerical Investigation Of Shock-Induced Combustion Past Blunt Projectiles, Jagjit K. Ahuja

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical study is conducted to simulate shock-induced combustion in premixed hydrogen-air mixtures at various free-stream conditions and parameters. Two-dimensional axisymmetric, reacting viscous flow over blunt projectiles is computed to study shock-induced combustion at Mach 5.11 and Mach 6.46 in hydrogen-air mixture. A seven-species, seven reactions finite rate hydrogen-air chemical reaction mechanism is used combined with a finite-difference, shock-fitting method to solve the complete set of Navier-Stokes and species conservation equations. In this approach, the bow shock represents a boundary of the computational domain and is treated as a discontinuity across which Rankine-Hugoniot conditions are applied. All interior details of …

Circulation Measurements About A Rapidly Pitching Airfoil Using An Ultrasonic System, F. J. Weber, Jr., William W. Durgin, H. Johari

Office of the Provost Scholarship

An ultrasonic system was developed to measure the circulation about a sinusoidally pitching NACA 4418 airfoil. The system consisted of two opposing ultrasonic ranging modules arranged such that the differences between the sound propagation times in opposite directions could be related to the instantaneous circulation. For the stationary airfoil, the measured lift coefficient was within 5% of the tabulated data while the observed stall angle was 2° less than the tabulated value. Measured hysteresis loops verified the applicability of the ultrasonic system to the dynamic stall problem. Measured maximum lift coefficients increased linearly with reduced frequency up to a value …

Field Commissioning Of A Daylight-Dimming Lighting System, Florida Solar Energy Center, David Floyd

FSEC Energy Research Center®

An Elementary School cafeteria in Florida was commissioned with a fluorescent lighting system that dims in response to available daylight. The lighting system's performance and commissioning aspects were evaluated through real time measurement of lighting and air conditioning power, work plane illumination, and interior/exterior site conditions. The new system produced a 27% reduction in lighting power due to dimming. Lower than expected dimming system performance was observed prior to effective commissioning. Difficulties encountered are discussed as well as recommendations for performance improvements.

Photovoltaic Applications For Disaster Relief. 11-95. Copies 1,2&3., Florida Solar Energy Center, William Young

FSEC Energy Research Center®

No abstract provided.

A Comparative Study Of The Stress Concentration Factors Arising Between Two Equal, Nearly Intersecting, Perpendicular, Pressurized Holes In An Infinite Solid With Those Arising Due To An Infinite Series Of Such Holes, Paul J. Drogowski

Masters Theses

Finite element analysis is used to determine the stress concentration factors arising from two equal, perpendicular, nearly intersecting, pressurized holes in an infinite solid while varying the distance and pressure ratios between the holes. The results are compared and contrasted with those previously obtained for an infinite series of such holes. A ratio of the distance between the holes to the diameter of the holes at which the holes can be considered to be single holes in an infinite solid is determined. A study is performed to determine a correlation between the location of the region of maximum stress and …

Effects Of Blowing Ratios On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Fu-Jung Chen

Theses and Dissertations

The effects of transpiration cooling on heat transfer in the throat region of a porous-walled nozzle were investigated. The experiments were performed in the AFIT low speed shock tube fitted with a Mach 2 nozzle. A blowing region was limited to the area from 1.3 cm prior to the throat to 1.2 cm downstream of the throat. The blowing ratios from -0.0002 (suction) to 0.0117 (blowing) of the main stream flow were studied. Heat flux data were taken from both sides of the nozzle. One side was transpiration cooled by secondary air injection through a porous wall, while the other …

Design And Development Of Microswitches For Micro-Electro-Mechanical Relay Matrices, Mark W. Phipps

Theses and Dissertations

Many different micro-electro-mechanical switches were designed in the Multi-User MEMS processes (MUMPs) and deep x-ray lithography and electroforming (LIGA) processes. The switches were composed of actuators that operated based upon either electrostatic forces or thermal forces. A thermally activated beam flexure actuator that operated based upon differential heating was used extensively. This actuator, which was fabricated in the MUMPs process, was able to deflect up to 12 microns with a total input power of less than 25 mW. The thermal resistance, which was needed to model this actuator, was determined from a material constant, 1.9 ± 0.08 m^1.5-°C-W …

Time Dependence Of Multiply Scattered Diffuse Ultrasound In Polycrystalline Media, Joseph A. Turner, Richard L. Weaver

Department of Engineering Mechanics: Faculty Publications

Time domain results are presented for the multiply scattered longitudinal intensity backscattered from a polycrystalline medium. The results are solutions to the ultrasonic radiative transfer equation (URTE), the derivation of which is based upon radiative transfer theory. Unlike steady-state solutions obtained previously, time domain solutions will more closely correspond to experiments that use tone burst sources. This paper is concerned with the time dependence of the backscattered longitudinal intensity from a polycrystalline medium excited by a normally incident longitudinal wave idealized as an impulsive deposition of energy. It is shown that multiple scattered effects become significant at times on the …

The Spectral Relaxation Model Of The Scalar Dissipation Rate In Homogeneous Turbulence, Rodney O. Fox

Rodney O. Fox

A model for the effect of scalar spectral relaxation on the scalar dissipation rate of an inert, passive scalar (Sc>1) in fully developed homogeneous turbulence is presented. In the model, wave-number space is divided into a finite number [the total number depending on the turbulence Reynolds number Re, and the Schmidt number (SC)] of intermediate stages whose time constants are determined from the velocity spectrum. The model accounts for the evolution of the scalar spectrum from an arbitrary initial shape to its fully developed form and its effect on the scalar dissipation rate for finite Re, and Sc>1. …

Relationship Of The Second Order Nonlinear Optical Coefficient To Bandgap In Inorganic Non-Centrosymmetric Crystals, A. G. Jackson, M. Ohmer, S. R. Leclair

Mechanical and Materials Engineering Faculty Publications

The purpose of this paper, is to provide a means of estimating and comparing the wavelength conversion efficiency (figure of merit, FOM) of new nonlinear materials knowing only their bandgap. The approach for the estimates is trend analysis of existing data^1-28 for the second order nonlinear coefficient, x⁽²⁾ijk, or d_ij =x⁽²⁾ijk^/2, the index of refraction n, and the bandgap E. No underlying physical basis for the result will be presented. The result of this trend analysis, in the form of plots of x⁽²⁾ vs E and FOM vs E …

Advanced Rover Chassis, Eric Alan Poulson, Collin Lewis, Todd Graves

Undergraduate Honors Capstone Projects

Background:

The six wheeled rover vehicle detailed in this design is intended as an upgrade test bed for the sensor array and autonomous navigation algorithms in use by Utah State University's Center for Self-Organizing and Intelligent Systems (CSOIS). The CSOIS's sensor suite can successfully detect and avoid unnavigable obstacles up to five vehicle lengths in front of the vehicle. The center presently uses a modified RC type chassis and only supports two wheel drive. This chassis was adequate to bring the CSOIS's algorithms to a proof-of-principles state, but in order to place the system in any practical application, a full …

Tractor Test Museum Committee Minutes April 21, 1995, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Hitchcock Foundation Potential Committee Member Tree Removal

Assessment Of Infiltration Practices In The Florida Energy Code, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

The Florida Department of Community Affairs has contracted with the Florida Solar Energy Center (FSEC) to review the current infiltration practices of the Florida Energy Code to determine, based on analysis of the best currently available infiltration data, whether there is need for three infiltration practices, and to make recommendations of what "point multipliers" should be applied to the infiltration practice(s). An advisory committee of industry, utility, and research representatives was formed to review the findings of the project and express opinions about the form the infiltration practices should take. This committee met twice, reviewed each of the reports produced …

Reduced Small Engine Emissions With Perforated Plates, Derek S. Lindsay

Honors Capstone Projects and Theses

No abstract provided.