Digital Commons Network^™

A Probabilistic Approach To The Design Of Heat Pipes, Charles C. Roberts Jr.

Mechanical Engineering ETDs

The design of heat pipes involves knowledge of phenomena such as surface tension forces, wick permeability, and fluid vaporization and condensation. Considerable variability in these phenomena has been observed in heat pipe experiments. Thus, a probabilistic design model for predicting heat pipe heat transfer rate has been developed taking into consideration uncertainty in the prediction of the above phenomena. The probabilistic model yields a mean, a standard deviation, and the distribution of heat transfer rate based on the means, standard deviations, and distributions of the design parameters. The probabilistic method is compared to experimental data from heat pipes with wire …

Peak Temperature Distribution In Steel Plates During Arc-Welding, Bhanuprakash M. Patel

Theses and Dissertations

The welding of steel plays an important role as a major fabricating process in industry. In the field of welding metallurgy, much attention is given to the effects which a welding arc or flame will have on the structure and properties of the metals being joined. The engineer is interested in the intensify and extent of physical changes brought about by the unavoidable heat treatment which accompanies the execution of a weld. In order to gain some quantitative appreciation of the way in which the metallurgical effects of welding depend on welding variables, geometry, and physical properties, considerable attention has …

Application Of The Finite Element Method Using The Method Of Weighted Residuals To Two Dimensional Newtonian Steady Flow With Constant Fluid Properties, Mien Ray Chi

Theses and Dissertations

In this thesis we will be concerned with the two-dimensional steady laminar Newtonian fluid flow with constant fluid properties in Cartesian coordinate system. More precisely, we will consider a flow for which the interesting dependent variables, for example, velocity, vorticity, stream function, etc., are expressible as functions of two independent Cartesian coordinates.

An Experimental Investigation Of The Relation Between The Cooling Rate And Welding Variables In Fusion Welding, Sujit Biswas

Theses and Dissertations

In the field of welding metallurgy, much attention is given to the effects which the welding arc or flame will have on the structure and properties of the metals being joined. The engineer is interested in the intensity and extent of physical changes brought about by the unavoidable "heat treatment" which accompanies the execution of a weld.

Rotary Engine Designs Based On A Particular Off-Set Cavity/Rotor System, M. Dean Black

Theses and Dissertations

The subject of this thesis is a family of rotary engines, each consisting of a two-tipped rotor turning about an off-center axis within a nearly round cavity.

Vibration And Buckling Of Elastic Plates With Shear And Rotatory Inertia, Bomi Batiwalla

Dissertations

The effects of shear, rotatory inertia and inplane forces on the transverse vibration of thin plates are studied. In addition, the effect of shear on the buckling of thin plates is examined. A general differential equation of motion is derived for an isotropic thin plate subjected to normal and inplane forces with the consideration of shear and rotatory inertia. The method of internal constraints and Hamilton's principle are utilized.

The resulting fourth order differential equation is solved for simply supported plates of various shapes by employing a finite difference technique. The shapes examined are a square, a circle, a circular …

The Creep And Stress Relaxation Behavior Of Silver Bearing Copper Wire, Alfred Fox

Theses

Creep and stress-relaxation experiments were performed on silverless and silver bearing copper in the temperature range 73F to 250F. The creep experiments were conducted at constant load and temperature, the stress-relaxation tests at constant total strain and temperature for a total time period of 1000 hours. The effect of silver addition of up to 0.2 percent w/o (60oz per ton) on the creep and stress-relaxation behavior of spectrographically pure copper (99.999+ Cu) as well as on that of tough pitch and oxygen free coppers of lesser purity was studied. Spectrographically pure copper was found to be much more susceptible to …

Determination Of Drag And Lift Coefficients For A Spinning Baseball, M. B. Parekh

Theses and Dissertations

Few experiments have been carried out in the past to deter mine the effect of the lift and the drag forces on the trajectory of a ball used in any game. In a baseball game, it was reported that sometimes the ball took a sharp turn aburptly in the region of 15 to 20 feet from the home plate. This indicated a sudden change of the forces acting on the ball. The principal forces acting w ere as fol lows: 1. Weight of the ball. 2. Drag force acting in the direction parallel to the relative wind. 3. Lift force …

The Optimum Design Of A Shock Absorber To Minimize The Force Transmitted To The Supporting Base Of A Vibrating Equipment, J. P. Singh

Theses and Dissertations

The present study involved two types of analyses as a part of the investigation leading to the design of a shock absorber providing optimal vibration control and minimum transmissibility. Those two types of analyses were the following.

Application Of The Maximum Deformation Theory Of Failure To The Torsional Failure Due To Fracture Of 4140 Steel, C. V. Krishna Kumar

Theses and Dissertations

Forming is the fastest way of changing the shape of a piece of metal. It is the most economical process to use for high-volume mass production when the shape of a part is such that it can be made by one of the forming operations

The Dynamic Characteristics Of A Beam Whose Material Is Represented By A Three-Parameter Viscoelastic Solid, Vishnurao K. Devkar

Theses and Dissertations

Man observes many phenomena occurring in nature which he can use to his benefit. He observes how physical quantities vary as a function of their environment in order to predict how these variations will affect a system he wishes to design. For this purpose, he must establish a model that is representative of the relation between those physical quantities and certain environments to which they are subjected.

Experimental Study On Viscoelastic Properties And Fracture Characteristics In Polymers, Debaranjan Mohanty

Electronic Theses and Dissertations

The research reported in this thesis is undertaken with the following objectives:
1. To determine the viscoelastic properties of polymers on creep test under constant load;
2. To determine the internal friction (loss factor) of polymers under periodic loading condition;
3. To determine the delayed time or life time on fracture of the polymer under constant loading ; and
4. To verify the relationship, theoretically predicted, between the time to fracture and the material characteristics of the polymer with experimental observations.

Modal Truncation Of Substructures Used In Vibration Analysis, Suresh Kumar Tolani

Doctoral Dissertations

"The objective of this study is to describe in a unified manner a group of structural dynamics analyses using the substructures technique. An additional effort is to provide a consistent basis for the selection of substructure principal modes as required by this method. Substructure principal mode frequency roots and strain energy are two criteria evaluated for the selection of substructure principal modes. System eigenvalues and system strain energy are investigated for the comparison of results in the principal modes. System strain energy should provide more rational results since it is proportional to the stress times the strain in the system …

An Experimental Investigation Of The Effects Of Ambient And Heated Steady Flow And Intense Sound Levels On The Response Of Acoustic Filter Elements, Raymond H. Schaffart

Doctoral Dissertations

"The primary purpose of this research was to investigate the effects of flow and finite amplitude waves on the response of acoustic elements. A further purpose was to evaluate the effects of elevated temperatures and cross-sectional dimensions on element performance. As an integral part of this work various laboratory techniques were explored for their suitability.

Empirical models for the acoustic impedance of side branch resonators were developed for the two operational modes, i.e., flow past the resonator and finite amplitude wave inputs. A description of the complex variation of the acoustic resistance of the resonator with flow past and variable …

Force Analysis Of Involute Spur Gears, Janakkumar Girjashanker Dave

Masters Theses

"This study is devoted to the fundamental action which occurs between spur gears with involute tooth profiles when power is transmitted at a constant angular velocity ratio. Various aspects of the interaction between two mating teeth are considered. Analytic expressions for the variation of the force transmitted between two teeth are derived. Two cases are considered which include and exclude the effects of sliding friction between the teeth. The parametric equations of the involute curves for two mating teeth are derived in terms of body-fixed coordinates. Analytical expressions for Hertz compressive stresses in the teeth were also obtained. The same …

An Analytical Study Of A Confined Viscous Vortex, David Edward Crow

Doctoral Dissertations

"A composite solution for the flow field of a three dimensional, incompressible laminar, viscous vortex confined inside a conical converging nozzle is presented. This model is used to study the strong mainstream boundary layer interaction that occurs in confined vortex flows. The confined vortex flow field is divided into mainstream and boundary layer regions. A particular class of solutions of the general equations of motion is used to represent the vortex flow in the mainstream region. That is, the tangential velocity in the mainstream region is assumed to be of the form W = T(e)/R. Velocity and pressure profiles from …

Design And Test An Operational Amplifier Speed Transducer, Tung-Ming Huang

Masters Theses

"This thesis describes the design of an angular speed transducer. The purpose of this device is to provide a D.C. voltage which is proportional to the angular speed of a rotating shaft at any instant. The speed of the shaft is defined from a magnetic pickup monitoring a gear or similar device attached to the end of the shaft of a piece of rotating equipment. The signal from the magnetic pickup is modified and compared to a frequency generated in the feedback loop of the speed transducer and the error is sent to an integral type controller. The output of …

Analysis Of A Substitute For The Impact Damper To Damp Near-Resonant Mechanical Vibrations, Nguyen Khanh Van

Masters Theses

"This report investigates a substitute for the impact damper which, although highly effective in reducing vibration amplitudes of near-resonant mechanical systems, in operation causes often unacceptable intensive noise. The present damper consists of a piston free to move in a cylinder, at either end of which is a ball valve set to open at a preset pressure, and in the middle along its length an intake port. An approximate analytical study is made to determine the conditions for the existence of "noiseless periodic operation" of the damper, periodic operation without the occurence of impacts. This approach is based on the …

Parametric Analyses Of Regenerative Steam Power Cycles, Vallabh Vithalbhai Vaghani

Masters Theses

"This study analyzes the effect of inlet pressures, internal turbine efficiencies, pump efficiencies, extraction pressures and number of open feedwater heaters on the thermal efficiency of regenerative steam power cycles. Combinations of inlet and extraction pressures were introduced into digital computer programs in order to find the optimum extraction pressures for maximum thermal efficiency. The scope of study covered regenerative steam cycles with one, two, three, four, and five open feedwater heaters. One of the principle objectives of the study was to determine if there is some turbine extraction pressure or set of pressures which give maximum thermal efficiency for …

A Study Of Plane Wave Filter Analysis With Flow, Thomas Valle Huber

Masters Theses

"The purpose of this investigation is to determine the effect of slow steady flow on the reflection and transmission characteristics of acoustic filters.

A standing wave tube and transmission tube apparatus, designed and built by a previous investigator, was modified to accept slow steady flow. Reflection characteristics were determined from measurements made on the inlet side of the filters investigated. These data along with measurements taken with the transmission tube apparatus were used to determine transmission characteristics. The calculations were simplified by terminating the filters anechoically. The filters used in this investigation were an expansion chamber, an automobile type muffler …

The Application Of Impact Dampers To Continuous Systems, Ranjit Kumar Roy

Doctoral Dissertations

"A study has been made of the application of impact dampers to two types of continuous systems, a simply supported and a clamped beam. Previous efforts have included the effect of impact dampers on single degree of freedom and other systems with finite numbers of degrees of freedom.

Experimental models were tested in the laboratory and finite element computer programs were developed to calculate response. Results from calculations agree favorably with experimental tests. Further, results from the first few natural modes also compare reasonably with data published on systems with finite number of degrees of freedom.

Curves are presented which …

Determination Of Thermal Contact Resistance Between Metals Using A Pulse Technique, William Edward Stewart Jr.

Doctoral Dissertations

"This dissertation reports the results of an experimental and analytical investigation to determine the thermal contact resistance of several metal specimen pairs using a relatively new pulse technique. Metal specimens were aluminum 2024-T3, aluminum 6061-T6, aluminum 7075-T6, copper 110, stainless steel 304, molybdenum, and Armco iron. Thermal contact resistance was also determined for dissimilar metal specimen pairs of aluminum 6061-T6 - copper 110 and aluminum 7075-T6 - copper 110. Aluminum 7075-T6, copper 110, and stainless steel 304 specimens were tested to determine the variance of contact resistance with time after loading.

Specimens were circular cylindrical disks between .033 and .061 …

The Analog Simulation Of Heat Transfer Devices For The Smoothing Of A Fluctuating Fluid Temperature, Le Thai Son

Masters Theses

"Equations are written to describe a heat exchanger with electrical energy input and also a large tank system which can have electrical energy input. The output temperatures were sampled and fedback to define the energy input to the two systems. These systems were simulated on an analog computer and the ability of the two systems to smooth a fluctuating temperature input was tested. The testing of the systems included trying different types of controllers in the control system as well as different size tanks for the tank system. A satisfactory smoothing of the output temperature was demonstrated after some modifications"--Abstract, …

Wind Tunnel Modeling Of The Atmospheric Boundary Layer, Sreemanth Pagadala

Masters Theses

"The importance of simulating atmospheric flows in wind tunnels has been well established. Experiments were conducted in the Modified Aerodynamic Wind Tunnel to determine the suitability of this wind tunnel for simulating atmospheric flows and the degree to which various aspects of modeling could be fulfilled. A temperature profile to simulate the inversion aloft was generated inside the test section, and then an appropriate velocity profile was built in by means of screen mesh arrangements. The turbulence characteristics of the flow were measured. The validity of the temperature, velocity and turbulence fields were examined. It was found that while the …

On The Complex Index Of Refraction For Liquids, Juan Guillermo Ochoa Sierra

Masters Theses

"Methods for determining the optical constants, the real and the imaginary part of the complex index of refraction, for weakly and strongly absorbing liquids are reviewed and evaluated. Both reflection and transmission methods were considered and preliminary steps are taken for determining the optical constants for both water and oil in the visible region (0.45 - 0.65 microns) of the spectrum. A low resolution spectrometer was used and the transmission measurements through fuel oil, number 1 through 6, and crude oil were performed. The imaginary part of the complex index of refraction was deduced from the above measurements and appears …

An Exact Analysis Of Two-Dimensional Radiative Transfer In An Absorbing And Emitting Gray Medium, William F. Breig

Doctoral Dissertations

"The exact formulations for the radiative flux and the emissive power are presented for a two-dimensional, finite, planar, absorbing and emitting, gray medium in radiative equilibrium. Exact expressions are obtained for the medium subjected to the following types of boundary conditions: (1) cosine varying diffuse, (2) cosine varying collimated, (3) constant temperature strip, and (4) the strip illuminated by a uniform collimated flux. The solutions for the physically unrealistic cosine varying models are used to construct the solutions for the more practical finite strip models. The two-dimensional equations are reduced to one-dimensional equations by the method of separation of variables. …

A Yield And Fracture Model For Ti-6al-4v Titanium And 7075-T6 Aluminum, Richard L. Pendleton

Doctoral Dissertations

"The objective of the research being reported in this thesis was to conduct a series of experiments on two commonly used structural metals in several different environmental pressures so that a graphical representation of the material response both to yielding and fracture could be ascertained. It was further intended to show that parameters herein defined and called effective stress, effective strain, and pressure are useful parameters for graphically representing the material response. The final goal of this research was to show that the graphical representation does, in fact, predict the yield and fracture for a simple forming process. The forming …

Design Of A Torsional Vibration Machine, Prafulchandra Pragjibhai Desai

Masters Theses

"In this thesis the design of the major components of a torsional vibration machine is presented. The machine is a torsional vibration actuator which will deliver a mean output angular velocity with a superimposed harmonic component. This type of motion can be used to study the torsional vibration characteristics of models representing crankshafts, gear trains, torsional dampers, and other systems. The primary machine elements of the actuator are a power source, flywheel, and a Hooke's joint. The power source consists of a D.C. shunt motor and a drive transmission using 3 V-belts. Through the use of a Hooke's joint, approximate …

The Effects Of Intense Sound Levels And Steady Flow On The Propagation Of Plane-Waves In Air, Wuu Hao

Masters Theses

"This thesis is a theoretical investigation of the effects of intense sound levels and steady flow on the propagation of plane-waves in tubes of constant diameter. The analysis is limited to a study of the change of wave profile due to the intense sound levels, and steady flow. However, corrections for effects of viscous and heat conduction losses at tube walls are also presented. To simplify the analysis, the problem is treated by considering the steady flow and finite-amplitude-sound wave effects separately. For finite-amplitude sound only, two approaches are evaluated. The first uses small perturbations to derive a finite-amplitude wave …

Drift Velocity Measurements Of Various Materials Floating On Water Waves, Paul Keith Scherrer

Masters Theses

"A study was conducted to determine the affects of deep water gravity waves on oil lenses and surface floats. The experiment was conducted in a wave tank equipped with a mechanical wave generator. The data obtained consisted of the measured velocities of oil lenses and thin plastic floats under the action of a variety of wave conditions. It was found that waves do cause a movement of the oil lenses and surface floats, and their velocity was found to be greater than the surface drift predicted by Stokes' theory of mass transport by waves in a single component fluid. For …