Mechanical Engineering Commons^™

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 …

Investigation Of A New Type Of Cloud Condensation Nuclei Counter: The Thermal Quench Chamber, Donald Arthur Hess

Masters Theses

"The design and development of a new type of cloud condensation nuclei counter was undertaken to provide a new laboratory and field instrument that operates on a different theoretical basis than the thermal diffusion chamber now being used by meteorologists and other scientists. In the new instrument the test aerosol is pumped through a tube where it is first humidified and then cooled at constant pressure to create a supersaturation, causing water vapor to condense upon the nuclei in the aerosol sample. The concentration of cloud condensation nuclei is then determined by counting the water drops. The control of temperature …

An Engineering Analysis Of Fluid Amplifiers And Development Of An Air Velocity Sensor, Gian Sagar Aneja

Masters Theses

"Fluidics, the new control technique finds its use amongst the conventional electronics and pneumatics due to some of its impressive features. Selected literature about bistable and proportional amplifiers has been presented for better understanding of the element behavior. Sensors; typical applications of fluidics have been described separately. An air flow velocity sensor has been set-up. Basically it consists of a cylinder placed across the air flow that sheds vortices in the wake due to 'Von Karman Vortex Street' phenomenon. The frequency of vortices gives a measure of velocity. The velocities obtained from the sensor have been compared to the ones …

Transient Cooling Of A Sphere Due To Boiling, Salil K. Banerjee

Masters Theses

"The time - dependent surface temperature is determined for a sphere subjected to cooling by boiling. One dimensional heat transfer is considered and the solid is assumed to be homogeneous, isotropic and opaque to thermal radiation and to have temperature independent physical properties. The initial temperature of the sphere and the coolant are assumed to be uniform and arbitrary. The boiling heat transfer coefficient at the surface of a sphere is a strong function of the surface temperature thus resulting in an extremely nonlinear transient heat conduction problem. As a practical application of the problem, the process of quenching has …

Methods And Applications Of Systems Identification, Allen Glenn Behring

Doctoral Dissertations

"A "Schmidt filter" is proposed to compute an optimal orthonormal basis for a set of "noisy" filter input functions. Procedures for determining the transfer function and inverse transfer function of the filter are given. The Schmidt filter is applied to the problem of determining mathematical models of discrete, stationary, linear, dynamic systems for the case where measurements may be corrupted by noise of unknown statistics. The identification problem is reconsidered for the case where noise and signal moments are specified. Procedures are given which insure unbiased, adaptive estimates of system order and parameters for this case. These theoretical propositions are …

A Practical Approach To The Exhaust Silencing Of A Pneumatic Rock Drill, Morton Gary Barth

Masters Theses

"One-third octave spectrum analyses of the exhaust noise produced by a medium sized pneumatic rock drill were obtained during free recriprocation to determine the most troublesome bands of noise. Noise reduction techniques were then used to design exhaust mufflers which would reduce the level of the exhaust noise to an acceptable level with a minimum increase in back pressure. The prototype mufflers evaluated included an expansion chamber, a resonator, and various modified expansion chambers. One of the modified expansion chambers tested provided very good attenuation reducing the exhaust noise from 113 dBA to 87 dBA at the operator's ear position. …

Application Of Transmission Matrices To Describe Transverse Vibrations Of Non-Uniform Bernoulli-Euler Beams, Dean Irle Parker

Masters Theses

"This report investigates the application of transmission Matrices to determine natural frequencies of non-uniform Bernoulli-Euler beams. The classes of non-uniform beams considered includes: truncated wedges, truncated cones, and truncated rectangular pyramids. Two transmission matrices were derived from solutions to the Bernoulli-Euler equation. One was an exact closed form solution which was applicable for the above classes of beams excluding uniform and nearly uniform beams. The second solution was an approximate one limited to the use for nearly uniform beams, but which does give the correct solution to the uniform beam in the limiting case. The transmission matrix has two advantages: …

Measurement Of Turbulence In An Annular Jet, George Philip

Masters Theses

"An experimental investigation was conducted for an annular jet which consisted of a circular jet and a concentric wake. The annular air jet mixed with quiescent atmospheric air. The jet velocity was kept constant at 137.0 feet per second which corresponds to a Reynolds Number of 73,200. Using the technique of hot-wire anemometry, mean velocities, turbulence intensities and Reynolds stresses were measured in the longitudinal and lateral directions. Two distinct flow regimes, the free stream jet regime and the diffusing jet regime, are observed. In the free stream jet regime, higher turbulence intensity and shear stress occur in the inner …

The Steady-State Response Of A Fluid-Filled Beam Near Resonance, Niranjan Jayantibhai Patel

Masters Theses

"In this report the steady-state near-resonant vibration of a hollow fluid-filled beam is considered. The energy dissipation caused by the beam-fluid interaction is approximated by introducing a viscous damping force into the Bernoulli-Euler beam equation. A theoretical expression is developed for the displacement of the hollow beam by solving this modified Bernoulli-Euler beam equation. Tests are made using a cantilevered fluid-filled box to simulate a unit of beam-fluid length. The band-width technique is used to determine the incremental viscous damping coefficient from test data. A variety of fluids are used in the box to determine the effect of the fluid …

Feasibility Study Of Using A Steam Power System In A Small Garden Tractor, Niranjan Kumar Doshi

Masters Theses

"This thesis is a feasibility study of using a steam power system in a small garden tractor. The relative advantages of steam power are discussed and compared with the characteristics of internal combustion engines. A monotube boiler is designed where steam is generated in stacked tube spirals. The boiler generates 225 lbs/hr of dry saturated steam at 500 psia, which corresponds to an engine output of 20 IHpage A rotary positive displacement engine is employed to expand the steam to 16 psia. A rotor instead of a piston eliminates the conventional connecting rod and crank shaft. The engine developes 15 …

Design And Construction Of A Drop Generator For Use In A Vertical Wind Tunnel, Danny Ray Conner

Masters Theses

"A drop generator, based on the principle of a vibrating capillary, was designed and built for use in the UMR vertical atmosphere wind tunnel. The drop generator worked very well on a test stand where it was firmly supported, but was not consistent when tested in the wind tunnel. Vibration of the wind tunnel walls and a slight turbulence near the forward edge of the generator caused an oscillation in the position of the stream of drops. The oscillation resulted in some of the drops hitting the edge of the collector cup, where the drops would accumulate until a large …