Mechanical Engineering Commons^™

A Theoretical Analysis Of The Free Vibrations Of A Clamped Circular Plate With Damping, Bhalchandra Krishnaji Vaidya

Masters Theses

"A theoretical analysis of the free vibrations of a clamped circular plate was undertaken. The effects of transverse shear were considered for application to relatively thick plates in which there exist sharp transients and frequencies corresponding to higher modes. The method adopted by R. D. Mindlin was used to develope [sic] the differential equation of motion for the plate. The damping effect due to the resistance of the medium in which the plate vibrates was also considered. This damping was assumed to be due to the generation of pressure waves caused by the displacement of the plate...Since the solution requires …

The Use Of Turbulence Energy Equation In Boundary Layer Study, Ro-Chi Tai

Masters Theses

"A turbulent boundary layer problem has been studied analytically and compared with an available experiment in the literature. Correlations of the experimental data were made to investigate the validity of the commonly used empirical relations on turbulent shear stresses. It was found that the model which related the local turbulent shear stress linearly with the local turbulent kinetic energy, as used by Bradshow et. al., appeared to be most reasonable. combining this model with the expression of turbulent viscosity given by Boussinesq, it was then possible to introduce the turbulence-energy equation in addition to the governing equations of continuity and …

Experimental Determination Of Dynamic Properties Of Aluminum Including Poisson's Ratio, Terry Lee Holman

Masters Theses

"Two rods of 7075-T651 aluminum are longitudinally impacted to investigate the material's dynamic properties. The test rod, initially at rest, is instrumented with strain gages to record the strain-time history after the impact rod, accelerated to uniform velocity by an air gun launcher, strikes the test rod. A camera records the strain-time pattern displayed on an oscilloscope. The experiment indicates a consistent rise time of approximately 9 µsec. Simple one-dimensional theory correlates well with the experimental data. Compensation is included for the transverse sensitivity of the gages used. The dynamic values for both the modulus of elasticity and Poisson's ratio …

A Comparison Of Lumped Parameter Models Commonly Used To Describe One-Dimensional Vibration Problems, Suresh Kumar Tolani

Masters Theses

"Three lumped parameter model representations of the one-dimensional uniform continuous system in a vibration state are examined. The exact (continuous) solutions were used as a reference to evaluate the accuracy of the results obtained via these discrete element models. The model comparisons, carried out for both the principal modes and the systems under forced excitations, are based on the maximum strain energy. The effect of varying the number of segments in the model representation showed improvement in approximating the exact strain energy solution as the number of segments was increased. In general, the results of the model comparisons based on …

Dynamic Response Of A Gyrocompass, Subhash Govind Kelkar

Masters Theses

"A gyrocompass with three degrees of freedom is studied and an attempt made to solve the exact equations of motion numerically. The equations are obtained by using the Lagrange formulation of the problem. The kinetic energy and the potential energy of the system are determined from the energies of the various components. These are then substituted into Lagrange's equation to obtain the three equations of motion for the three angular coordinates. As few restrictive assumptions as possible are made during this development. From these exact equations of motion an approximate analytical solution is obtained by making several assumptions and then …

The Design Of A Direct Current Generator Field Controller, Melvyn Elwin Downs

Masters Theses

"A controller was built utilizing transistors and silicon controlled rectifiers to allow torque control of the General Electric dynamometer, type TLC-50. The current gain of the controller was approximately 10⁶ such that the field current could be controlled by an input current of zero to approximately two microaaperes. The transfer function for the controller-dynamometer system was experimentally determined. The results indicate that the gain of the open loop torque control system is constant for frequencies up to 1.1 radians per second. Satisfactory values of gain for proportional and proportional plus integral control, were experimentally determined by operating the closed loop …

Dynamic Response Of Circular Plates To Transient And Harmonic Transverse Loads Including The Effect Of Transverse Shear And Rotary Inertia, Perakatte Joseph George

Doctoral Dissertations

"Using an improved theory of plate vibration suggested by R. D. Mindlin which takes into account the effects of transverse shear and rotary inertia, free and forced transverse vibrations of uniform circular plates are studied and the results compared with those obtained using the classical theory of plate vibration. The governing equations are developed in polar coordinates using the equations of elasticity. Frequency equations for axisymmetric and antisymmetric vibrations are derived for solid circular plates under different boundary conditions and for an annular plate rigidly mounted on a shaft. The response of plates to different types of rapidly applied axisymmetric …

A Finite Element Method For Geometrically Nonlinear Large Displacement Problems In Thin, Elastic Plates And Shells, Ronald August Melliere

Doctoral Dissertations

"A finite element method is presented for geometrically nonlinear large displacement problems in thin, elastic plates and shells of arbitrary shape and boundary conditions subject to externally applied concentrated or distributed loading. The initially flat plate or curved shell is idealized as an assemblage of flat, triangular plate, finite elements representing both membrane and flexural properties. The 'geometrical' stiffness of the resulting eighteen degree-of-freedom triangular element is derived from a purely geometrical standpoint. This stiffness in conjunction with the standard small displacement 'elastic' stiffness is used in the linear-incremental approach to obtain numerical solutions to the large displacement problem. Only …

Analytical And Experimental Methods For Determining The Properties Of Materials At Very High Rates Of Loading, A. G. Behring

Masters Theses

"In the following report, some of the properties of ALCOA 7075 T651 aluminum, when subjected to high rates of loading, are experimentally investigated by impacting two rods of the material longitudinally. One rod is accelerated to a uniform velocity with an air gun launcher. The stationary second rod is instrumented with strain gages on its lateral surface in order to determine the strain-time history following impact. A detailed description of the experimental equipment is included. Simple, one-dimensional theory is used to determine the dynamic, elastic modulus of the test material under the impact condition. Several observations regarding the behavior of …

A Study Of Swirling Air Flow In A Converging Nozzle, Charles William Lineberry

Masters Theses

"A study was conducted to determine the behavior of swirling air flow in a converging nozzle. Special instrumentation was constructed to obtain radial traverses of the flow at four axial positions. the data collected consisted of velocity, static pressure, and stagnation temperature. The flow pattern demonstrated the Ranque-Hilsh effect and reversed axial flow in the core region. As the flow entered the nozzle, it had the characteristics of a free vortex. At the exit plane the characteristics were those of a forced vortex. The converging nozzle caused an increase in the magnitude of the axial velocity component"--Abstract, page ii.

An Experimental Method Of Determining The Thermal Accommodation Coefficients Of Metallic Surfaces, Raymond John Dethorne

Masters Theses

"In the free molecule regime, Knudsen number greater than 10, heat is transferred from a solid by radiation and conduction. The ability of a surface to emit radiant energy is governed by a surface property called emittance while the surface property which apparently regulates the amount of heat transferred by conduction is called the thermal accommodation coefficient. This thesis presents the results of an experimental investigation to determine a relationship between these two properties, emittance and thermal accommodation coefficient. A test apparatus was constructed to measure both the radiation and conduction contributions between two concentric cylinders. cylinders of aluminum and …

Investigation Of Thermal Resistance At The Interface Of Dissimilar And Similar Metals, Ching-Liang Lin

Masters Theses

"Experiments have been conducted to investigate the resistance and the effect of the directional heat flow at the interface of metals in contact. The test specimens were cylinders, axially aligned and dead weight loaded. Specimen materials were aluminum, bronze, and steel. The tests were conducted at environment pressures of 5x10⁻⁵ Torr. or less. The dead weight load was kept at 10 lbs. for all tests and the surface roughness for all specimens was from 6 to 8x10⁻⁶ inch. The results of the investigation reveal that the resistance to heat flow at the interface of metals decreases as the interface temperature …

Instrumentation Of A Shock Tube Facility, James Everett West

Masters Theses

"The theory of schlieren and interferometer systems was described and related to studies of shock waves in a shock tube. An interferometer was procured and a schlieren system was modified for use with the UMR shock tube facility. The design and construction of a base for the systems and window assemblies for the shock tube comprised the major portion of the work on this project. A short series of tests were run to ascertain the compatibility of the instrumentation to the UMR shock tube facility. While no schlieren photograph of the shock wave was obtained, the system was shown to …

Constant Horizontal Force Machining Through Flash Welded Steel Bars Of Varying Hardness, Donald Naeger

Masters Theses

"The purpose of this experiment was to determine the effect of a constant horizontal force applied to the carriage of a lathe as it turned a piece of stock which consisted of two steel bars, of different hardness, flash welded together. This experiment was performed on a lathe to which a pulley system with a mechanical advantage of six was attached to the carriage. The strain on the tool was measured both in the horizontal and vertical directions by a tool dynamometer on which eight strain gages were mounted. The strain gages were calibrated on a Tinius-Olsen testing machine. The …

Coupled Transport Of Heat And Mass In Laminar Tube Flow, Lung-Mau Huang

Masters Theses

"The object of this investigation is to study the mutual dependence of heat and mass transport in laminar and hydrodynamically developed tube flow. Consideration is given to gas flow through a tube whose wall is coated with a sublimable materials so that heat and mass transfers take place between the wall and the flowing gas stream. The tube wall is thermally insulated from the external environment, with the result that the latent heat required by the sublimation process at the wall is supplied solely by convective transfer from the gas. The analysis of the problem requires simultaneous solution of the …

Evaluation Of Methods For Analysis Of Multi-Degree-Of-Freedom Systems With Damping, Brijgopal R. Mohta

Masters Theses

"A general review of various methods for studying the behavior of linear lumped parameter systems with viscous damping is presented. Five methods are discussed. These are: (1) Normal Mode Technique (2) Ho's Method (3) Impedance Method (4) Graphical Technique (5) A Method for Reducing Degrees-of-freedom. For solution of vibration problems by the Normal Mode Technique, the systems are classified as (1) classically damped or (2) non-classically damped. It is shown that the classically damped systems are relatively easy to solve. For non-classically damped systems, the method proposed by K. A. Foss has been employed. This method is quite complex, but …

Numerical Integration Of Shell Equations Using The Field Method, Pravin R. Ghael

Masters Theses

"In this work field equations are introduced to numerically solve the six linear differential equations which determine the displacements and stress resultants for thin elastic shells with axially symmetric loadings. With the applications of the field equations to the analysis of symmetric shells, the two-point boundary-value problem is formulated in terms of twelve first-order ordinary differential equations with boundary conditions at only one point. These equations are solved by using a forth [sic]-order Runge_kutta integration formula. Three problems whose solutions are known have been evaluated to check the accuracy of the field equation method. These are: (1.) Simply-supported, thin circular …

Film Boiling Of Nitrogen From A Spherical Heating Surface At Atmospheric Pressure And Standard Gravity, Juan Jorge MariáNyi

Masters Theses

"A steady state film boiling heat transfer study was conducted at atmospheric pressure, with a heated sphere as the heat transfer surface and liquid nitrogen as the boiling medium. Results indicate that the heat transfer rate in film boiling is not the same around the sphere. For the same heat flux, heat transfer at the sides of the sphere takes place at higher temperatures than at the bottom of the sphere. The data were compared with the equation of Frederking and Clark for spheres (1̲8̲), which was derived to predict steady state conditions at standard, fractional and near zero gravity. …

A Fluidic Liquid Level Control System, Vinod Kumar Verma

Masters Theses

"The prime objective of this investigation was to design and construct a working "Fluidic liquid level control system", and to make a functional study of the characteristics of the devices employed therein. A working model of a "fluidic liquid level control system" is developed and experimental data is collected to describe the functional characteristics of the fluidic circuits employed. The system contains a pressure sensitive, variable frequency oscillator; appropriate demodulation stages to convert the variable frequency alternating signal into a varying non-alternating signal; and on-off control elements in the final stages"--Abstract, page ii.

An Unsteady-State Method For Determining The Thermal Conductivity Of Materials, Richard H. Bulmer

Masters Theses

"Originally this work was initiated to develope [sic] a method for measuring the thermal diffusivity and thermal conductivity of metals. Due to the characteristics of the method and the equipment used, it was concluded that the technique is not suitable for materials of high conductivity. However, results show that the apparatus is valuable for the determination of the thermal diffusivity of relatively poor heat conductors. The favorable characteristics of the method are its rapidity and basic simplicity"--Abstract, page ii.

Drag Reduction In Hydrocarbon Soap Solutions, Ian Radin

Masters Theses

"Turbulent flow pressure drop measurements were made for solutions of aluminum dioleate (soap) in toluene at concentrations of 0.2, 0.5, 0.75 and 1.0 per cent. Tube diameters ranged in size from 0.01 to 2.0 inches. The results of these measurements differed from those observed in aqueous systems. Higher concentrations (at least 0.75 per cent) were required before drag reduction was observed. Although fresh solutions were somewhat sensitive to shearing, once a solution was over about two weeks old it showed little further mechanical degradation. Although in the toluene solutions, wall shear stresses were reached which were over an order of …

The Transient Dynamics Of Plane Mechanisms, Navnit Chhaganlal Mehta

Doctoral Dissertations

"Accurate determination of dynamic characteristics of mechanisms has become more important with increased requirements on speed, efficiency and precision. Many devices, such as circuit breakers and computing mechanisms, operate under purely transient conditions and actuation time places a serious limitation on the response of the system of which these devices are a part.

In the classical analysis, whether it be graphical or analytical, the mechanism is assigned a specified position and state of motion from which the forces required to produce the motion can be determined. The inverse problem of specifying the driving force and determining the resulting motion, which …

The Design And Construction Of An Apparatus For The Plane Wave Analysis Of Mufflers, Stephen Philip Buckley

Masters Theses

"In the following report, a method for evaluating the attenuation characteristics of a general muffler as well as the design, construction and use of the associated apparatus are described. The method combines accepted plane wave theory and experimental techniques into a relatively straightforward approach to the analysis of acoustic filters. Equations are developed to cover the frequency range between 300 and 4000 cycles per second. Deviations from these equations extend the use of the equipment to low frequencies without the need for unduly long and cumbersome apparatus. This method, which may be called the standing wave method, utilizes a standing …

A Study Of Film Boiling Of Liquid Nitrogen And Liquid Argon Over A Wide Pressure Range With Cylindrical Heaters, V. J. Flanigan

Masters Theses

""A film boiling heat transfer study was conducted with three different diameter cylindrical copper heaters over a wide range of pressures for nitrogen and argon with the heat transfer surface in the horizontal position. The data were compared to the commonly used film boiling heat transfer relations. The common relations were found to be considerably in error for the range of variables covered in this investigation. A semi-empirical equation for corresponding states fluids which correlates the available data as a function of the reduced temperature and reduced pressure was derived and discussed"--Abstract, page iii.

An Investigation Of The Effects Of An Impact On Some Of The Mechanical Properties Of Aluminum Alloy 2014-T6, Rajnikant K. Shah

Masters Theses

"Static and impact tests were conducted on an Aluminum alloy 2014-T6 specimen. The purpose of this research was to determine the effects of an impact load on some of the mechanical properties of aluminum. The cross section of the specimen measured 4.438 in. by 3.850 in. and it was 12 in. long. It was equipped with a total of four electric resistance gages connected in two pairs. One pair measured longitudinal strain while the other measured transverse strain. Both gages in each pair were mounted on the opposite sides to cancel the bending effect. In the static tests, load was …

Film Boiling From Horizontal Plates With Low Thermal Capacity, K. M. Ragsdell

Masters Theses

"The object of this investigation was to obtain data for saturated film pool boiling from a low thermal capacity flat plate at atmospheric pressure. A test plate, constructed from resistance strip, was placed horizontally in a pool of liquid, and was heated electrically. Refrigerant-11 and nitrogen were used as the boiling liquids. Heat transfer results were obtained in both fluids over a temperature range of approximately 1200F⁰ (400-1600⁰F). Surface size, roughness and orientation effects were observed for flat horizontal heated surfaces with one dimension near the most dangerous wavelength. No surface material effect was observed. Excellent correlation of the data …

Optimum Fin Spacing For Heat Transfer Per Unit Length Of Heat Exchange Section, Glenn Ellis Miller

Masters Theses

"This thesis presents the results of an experimental study of the heat-transfer ability of a finned surface as a function of the spacing between fins. The results are expressed as heat transfer per unit length of finned section rather than the heat transfer per fin. Circumferential steel fins, seven and three-quarter inches in diameter, were used for the investigation. Data was taken for fin spacings ranging from zero to one and one-half inches. The experimental heat-transfer rate to atmospheric air was determined by measuring the volume of saturated steam which condensed in the test section over a measured time interval. …

Convective Heat Transfer In Small Cylindrical Enclosures Heated From Below, Donald Wayne Land

Masters Theses

"Free convection in enclosed air spaces is often of prime importance in the design and analysis of panels utilizing the insulating properties of air and other gases. Previous investigations were performed on very thin air layers.

This thesis presents the results of an experimental investigation to determine the heat transfer by convection and conduction through air layers with relative sizes in terms of length/diameter ratios of one-fourth to one.

Eight cylindrical samples were tested. Four had inside diameters of 2.0 inches, and the others were 2.75 inches in diameter. Heat was transferred across the air layers by both conduction and …

A Study Of Modified Plug Designs For A Globe Valve, Robert W. Wagner

Masters Theses

"This thesis presents an empirical study of the characteristics of a cylindrical skirted disk valve used as a flow regulating device. Holes were drilled in two separate removable cylinders, which, when respectively attached to the valve plug adapter, provided control of the flow rate. These cylinders could be moved to permit exposure of more or less flow area by means of the valve stem and crank mechanism. At the closed position of the valve no holes were available for flow within the differential pressure zone of the valve, while at the full-open position all the drilled holes were within the …

Approximate Solution Of The Momentum And Energy Equations For Partially Ionized Argon, Sir-Hoi Chen

Masters Theses

"Based on available experimental data, the transport properties of partially ionized argon gas have been determined by solving the integral equations of momentum and energy conservation by an approximate method. The momentum and the energy conservation integral equations are solved simultaneously by an iteration method by assuming both parabolic and cubic velocity and temperature profiles separately. The results are compared with the case of linear velocity and temperature profiles"--Abstract, page iii.