Engineering Commons^™

A Comparison Of Analytical And Experimental Approaches In Determining The Thermoelastic Stresses Around A Cylindrical Inclusion Of Elliptical Cross-Section, Kenneth Byron Oster

Masters Theses

"Three approaches are used to determine the principal stress differences in an infinite elastic medium containing a cylindrical inclusion of elliptic cross-section due to a uniform temperature change. First, the two-dimensional equations of thermoelasticity are solved resulting in equations for the stress components anywhere in the medium material. Second, boundary displacements based on stress-strain relations are used as input displacements in a finite element program of the medium. Third, these same boundary displacements are used as input displacements on a photoelastic model simulating the medium. The problem is treated as one of plane strain in the first approach and one …

Comparative Study Of Lightweight And Normal Weight Concrete In Flexure, Mohammad Zareh

Dissertations and Theses

This investigation represents a comparative study of the flexural behavior of lightweight and normal weight concrete. Both theoretical and experimental moment-curvature characteristics of the tested specimens were used to study the flexural behavior.

A generalized computer program to determine the moment-curvature relationships of a singly reinforced rectangular concrete beam was developed.

For this limited study it was observed that lightweight concrete beams when compared to normal concrete beams achieve comparable moment capacity (about 92% of normal weight concrete) but exhibit higher deflections (about 40% more than normal weight concrete).

Normal Mode Method Applied To The Transient Longitudinal Vibrations Of A Finite Rod With Material Damping And Viscoelastic Dispersion, David Arthur Levene

Masters Theses

"Longitudinal vibrations of a finite rod with material damping and frequency dependent material properties are examined. The normal mode method is used to investigate the transient response of a rod which is free to move in the longitudinal direction and is subjected to a transient longitudinal loading condition at one end. The equations of motion are derived and solved using both the differential equations approach and the energy methods approach of the normal mode method. The effects of material damping and frequency dependent material properties are considered by formulating the stress-strain relation for the material such that the modulus of …

An Energy Solution For Vibration Characteristics Of Free Thin Cylinders, Dale Elmer Leanhardt

Masters Theses

"In this report the flexural vibrations of the walls of free, thin, circular cylinders are considered. Theoretical expressions are developed for the natural frequencies by extending the approximate energy method of Arnold and Warburton to the free-free case. Furthermore, the developed expressions are shown to apply, as special cases, to the fixed-fixed and simply-supported cylinders analyzed by Arnold and Warburton. The energy solution for free-free cylinders is checked both experimentally using a 3500 pound-force, 5 to 2000 hertz, vibration exciter and numerically using the well documented SABOR IV-DYNAL finite element program. While the derived energy method accounts for any prescribed …

Hydrostatic Extrusion Of Tubular Products, John Lester Roth

Masters Theses

"The production of quality tubular products by hydrostatic extrusion has been demonstrated to be a highly satisfactory method. The forming of tubes by the floating mandrel method has been accomplished on mild steel, aluminum alloy, and brass. This thesis describes the method, equipment design and operation, and the results obtained in the hydrostatic tube extrusion. A discussion on the advantages of the use of hydrostatic over conventional extrusion is included. The hydrostatic extrusion system designed for this study is described in detail"--Abstract, page ii.

Free Vibrations Of Circular Cylindrical Shells, Sushil Kumar Sharma

Masters Theses

"In this report bending theory of shells is used to determine the natural frequencies and mode shapes of circular cylindrical shells. The governing eighth-order system of differential equations has been put in a form which is especially suitable for numerical integration and application of different sets of homogeneous boundary conditions. The Holzer method is used to solve the eigenvalue problem. During numerical integration of the differential equations, the exponentially growing solutions are suppressed whenever they become larger than previously selected values. Numerical results are obtained for various shell geometry parameters and for three different sets of homogeneous boundary conditions. These …

An Investigation Of Stress In The Monowall Construction System Subjected To Racking Loads, Louis Alex Kuhlmann

Masters Theses

"Several methods of analysis were employed to investigate the stress conditions of concrete block built in the MONOWALL Construction System, when subjected to racking loads. MONOWALL is a technique of assembling blocks with adhesive rather than conventional portland cement mortar. The analyses used in this study included strain gages on full-scale walls, photoelastic models, and a mathematical solution. Each method of analysis is reported separately in detail and the results compared to each other"--Abstract, page ii.

Continuous Interfacial Polycondensation Of Nylon 6-10, Sumer Raj Hundia

Theses

Nylon 6-10 has been prepared by continuous interfacial polycondensation hexamethylenedlamine and sebacoyl chloride in a stirred system. The effect of monomer concentration and stirring on the intrinsic viscosity of the polyamide 6-10 solution in m-cresol was measured.

As stirring (RPM) and monomer increased the intrinsic and the polymer yield through a maximum. Diffusion coefficients (D_AB) for hexamethylenedlamine were for hexamethylenedlamine were and were used for the calculations of j_D factors and K/DAB ratios. A relationship and j_D factors was established by a correlation curve.

A Study Of The Effects Of Pressure-Induced Viscosity Changes On The Fluid Flow Characteristics In A Circular Tube, Robert Charles Weber

Masters Theses

"A method of determining the response of fluids under high pressure to quick-release into the atmosphere is presented in this report. The analytical efforts have been formulated into two parts, a closed-form solution and a numerical analysis. By assuming constant viscosity of the fluid a closed-form solution was obtained. The assumption of constant viscosity was found to be acceptable for the test fluids up to an initial pressure of approximately 10,000 psi. A numerical analysis became necessary for initial pressures over 10,000 psi, where the variable viscosity of the fluid had to be considered. The experimental work was conducted by …

Failure Of Lined And Unlined Small-Scale Cavities In Rock-Like Materials, Seung-Ki Yang

Masters Theses

"The strain conditions around statically loaded circular openings in rock-like materials and corresponding cavity-wall displacements were determined experimentally with resistance strain gages. The models were fabricated with lined and unlined openings simulating underground tunnels. Tests were performed with models of two different materials in plane stress and plane strain. Rock-like materials were designed and the strain gages were embedded at selected points within each model. The models often failed by tensile splitting through the opening early in the loading cycle causing the strains at certain points to deviate considerably from the theoretical values. Tangential strains on the vertical axis were …

The Design, Construction And Experimental Verification Of A Split Hopkinson Bar, Woosoon Bai

Masters Theses

"This thesis presents the design considerations for a dynamic loading device utilizing a projectile fired from a tube. Also included is a preliminary investigation of the stress-strain relation, under dynamic loading with the device, for a plaster known as Hydrostone. Design of the unit is based on the split Hopkinson pressure bar originally developed by Kolsky and on a similar unit in use at the Lawrence Radiation Laboratory, Livermore, California. The strain pulses along the pressure bars are sensed by resistance wire strain gages and displayed on an oscilloscope. The oscilloscope traces are photographed and manually digitized for insertion into …

Vibration Of An Internally Damped Tapered Truncated Cantilever Beam, Chimanbhai Magandas Patel

Masters Theses

"This thesis provides a vibration analysis of an internally damped, tapered, truncated, cantilever beam. Using two formulations of the problem based on: (1) Discrete mass and (2) continuous mass distribution, solutions are given for a beam having square cross section with linear depth and linear width variation. A Kelvin viscoelastic material for the beam is assumed. The vibration of the beam is considered to produce plane stress in the material, and the stress-strain relationship is applied only to the strain in the plane of bending. An exact solution for frequency of oscillation, mode shape, and steady state response is obtained …

Effects Of Pressure On The Mechanical Properties Of Magnesium, Joseph George Hoeg

Masters Theses

"The data collected in an attempt to evaluate the pressure dependency of the mechanical properties of extruded AZ31B-F magnesium alloy are presented herein. This information was compiled from the results of compression tests run in hydraulic fluid environments pressurized to 50,000 psi, and tension tests run in the atmosphere. Specimen axial load and longitudinal strain were recorded and converted to effective stress and effective strain parameters for presentation. The term pressure is defined, in this report, as the negative average of the principal stresses or, essentially, the negative of the hydrostatic component of stress. The effective stress and strain, at …

An Analysis Of Dirac Delta Generated Spherical Waves In An Infinite Maxwell Medium, William F. Breig

Masters Theses

"It is an accepted fact that the simple Maxwell and Voigt models do not usually represent the behavior of real materials. In order to make the results of a model more realistic, other combinations of springs and dashpots must be considered. To understand the more complicated models, it is desirable to have a knowledge of the Maxwell model since this element usually occurs either in series or in parallel in the advanced models. This investigation reports solutions of the spherical wave equation in both the elastic and viscoelastic media. Laplace transform techniques are used to obtain the parameters; stress, velocity, …

A Numerical (Matrix) Solution For The Vibration Frequencies And Modes Of A Nonuniform Rectangular Plate With Arbitrary Edge Conditions, F. David Utterback

Masters Theses

"The material presented in this thesis is designed to provide the practicing engineer with a practical, approximate method of solution for the increasingly important problem of plate vibrations. The technique presented herein is basically an application of the use of generalized coordinates to describe the elastic and inertial properties of a finite element representation of a nonuniform rectangular plate. The plate will be idealized by utilizing a modification of the grid work technique developed by Hrennifkoff as a lattice work of interconnecting beams. By employing the elastic displacements as generalized coordinates, the only required compatibility conditions are that the displacements …

Plastic Deformation Of Thin Plates With A Spherical Indenter, Benjamin Jen-An Chang

Masters Theses

"A method of determining the stress distribution in a thin plate deformed with a spherical indenter is presented in this report. The analysis is formulated in cylindrical coordinates and utilizes the basic principles of plasticity (von Mises yield criteria, Luwig stress-strain equation, Hencky Deformation theory, etc.). The problem is solved through the utility of a displacement function that, by virtue of its definition, automatically assures that the condition of volume constancy is satisfied. The boundary conditions are selected on the basis of having average, or integrated, effects corresponding to the physical constraints of the problem. Numerical integration is introduced to …

Dynamic Response Of A Simply Supported Beam To An Accelerating Point Load, Joseph Victor Cusumano

Masters Theses

"An analysis based on linear theory is presented for determining the dynamic response of a simply supported beam on an elastic foundation acted upon by a moving time dependent point force with axial forces included. This thesis extends the present theory to include an analysis of a point force accelerating uniformly across the beam. In particular, it is shown that the customary resonance conditions which are prevalent for a point force moving with uniform velocity no longer exist for the case of a point force accelerating uniformly across the beam.

The basic problem and its solution are presented for a …

Collision And Pursuit Course Terminal Closures For Spacecraft To Satellite Rendezvous, John Anthony Campbell

Masters Theses

"Collision and pursuit course closure maneuvers were studied for correcting position and velocity errors in the terminal phase of spacecraft to satellite rendezvous.

Minimum values of the ratio of initial range to velocity necessary to achieve rendezvous were determined for collision closures as a function of the initial line of sight. The time and velocity increment required for rendezvous were computed as a function of initial conditions.

Pursuit closure maneuvers were analyzed and time and velocity increments defined as a function of initial range, closing velocity, line of sight angle and angular velocity.

The velocity increments required were significantly higher …

Stresses In A Thick Spherical Shell, David Wayne Moore

Masters Theses

"This thesis reports a method to evaluate the stresses in a segment of a thick spherical shell. In the numerical examples loads due to thermal expansion as the shell is constrained at the free edge and a dead load acting vertically downward were considered for a shell assumed pinned but free to rotate and for a shell assumed completely fixed at the edge. A concrete shell was specifically studied but the method would also apply to a shell of any homogeneous, isotropic material"--Abstract, page i.

A Photoelastic Study Of The Stresses In A Deep Beam Using Partial Mirrors For Isochromatic Fringe Sharpening And Fringe Multiplication, Edward M. Raney

Masters Theses

"This paper is a photoelastic investigation of the stresses in a deep beam using partial mirrors to obtain isocromatic fringe sharpening and fringe multiplication. This method may be of particular value in photoelastic work for obtaining full field fringe multiplication and fringe sharpening for models which exhibit low fringe orders.

The photoelastic model used in this investigation is a deep beam with a length to depth ratio of one. A uniform load is applied over the center one-half of the beam. The beam is supported by two uniform loads distributed over a length of one-quarter the span.

A first approximation …

Comparison Of Plastic Stress-Strain Material Properties As Determined From Conventional Experiments, Wen Mo Chen

Masters Theses

"In problems of engineering design, it is usually assumed that the stress-strain diagrams of a given material, as obtained from different loading conditions, are the same. In fact, by using the classical theory of plasticity, it can be shown that, with an appropriate selection of stress and strain related parameters, the diagrams should coincide.

Three different materials - magnesium, aluminum and steel, have been tested under tension, compression, torsion and bending loads. Stress-strain diagrams were constructed from these observations. This thesis presents an analysis of the relative agreement between the theoretical and experimental results of these materials"--Abstract, page i.

Modal Characteristics Of A Vibrating Truss, Edd Leighman Ghent Jr.

Masters Theses

"In this thesis, a complete technique is presented for the vibration analysis of any planar structure which can be classified in the broad category of trusses or frames. Although a theoretical backdrop is included for the' sake of completeness, the intent is to provide a technique that is readily adapted to computer usage and can be handled with a minimum of confusion or misunderstanding.

The problem is solved by the use of a displacement technique wherein the inertia and stiffness properties of a structure are calculated by superimposing the contributions of each component of the structure. The calculation of these …

The Effect Of Combined Torsional And Bending Loads On A Channel Beam With One End Restrained From Warping, David M. Schaeffer

Masters Theses

"Channel beams have been designed with the main purpose of giving large resistance to bending while the torsional strengths are known to be relatively small. In this experiment, a cantilevered channel beam was loaded with a concentrated load at the free end, first through the experimentally determined shear center and then through the centroid of the cross section. For each loading condition, the strains were measured with the aid of SR-4 strain gages placed at intervals along the length of the beam. With the aid of a computer, the strains were converted into longitudinal stresses and these stresses were compared …

A Study Of The Flow Characteristics In The Core Region Of The Sandia Engineering Reactor, James A. Moeller

Chemical and Biological Engineering ETDs

The core region of a nuclear rector is an extremely compact area with a capability of providing a very high heat output. Regardless of the type of coolant used, the heat transfer characteristics of this region must be adequately designed to prevent any undesirable "hot-spots" from developing. The Sandia Engineering Reactor has one of the most compact cores of any in currently operating nuclear reactors. For this reason it is necessary to investigate fully the heat transfer characteristics of the core. The rate of heat transfer from the fuel elements to the coolant is directly dependent upon the temperature difference …