Engineering Commons^™

Temperature And Stress Distributions Produced In Long Circular Cylinders Cooled By Emission Of Thermal Radiation, Robert S. Pritchard

Mechanical Engineering ETDs

This study involves the determination of the temperature and stress distributions produced in long circumferentially symmetric circular cylinders cooled by emission of thermal radiation from the lateral surface. Temperature and strain responses obtained from an experimental model are presented for a set of parameters which correspond to the highest strain level which could be accurately determined with the strain gages. These responses are in good agreement with the results obtained by solution of an appropriate mathematical model. Temperature responses obtained from the same model, but having a higher initial temperature, are also presented and compared with analytical results. Reasonably good …

Galvanomagnetic Effects And Related Phenonmenon In Semiconductors And Dielectrics In A Radiation Environment, Leroy C. Meyer

Electrical and Computer Engineering ETDs

From Introduction:

In 1878, Hall found that the stream lines of an electric current in a metallic conductor were distorted when the conductor was placed in an external magnetic field. This distortion arises from an electric field set up at right angles to the current and to the magnetic field. The effect is well known in conductors and semiconductors, for both steady state and low frequencies Figure 1-1 illustrates the polarities of the Hall voltage for Ix in the direction of conventional current flow.

Experimental Investigation Of Free Field Conditions In Tanks To Be Used In Interaction Studies, Clark P. Sanger

Civil Engineering ETDs

Experiments to determine the effects of boundary friction losses on static and dynamic vertical stress transmission and to determine the stress-strain relationship of standard 20-30 Ottawa sand in 8-inch-I.D. tanks to be used in burial structure interaction studies are presented. In these tests the tank height, boundary condition, sand density, and overpressure rise time were varied. The use of a greased rubber membrane proved to be a reliable method of minimizing the boundary friction losses thus creating a strain field that was independent of the tank height. Vertical stress transmission was not affected by the overpressure load rate. The stress-strain …

Cavity Effect In A Pressure Bar, Kenneth B. Simmons

Mechanical Engineering ETDs

The investigation deals with certain aspects of wave propagation in a rod containing a penny-shaped cavity, particularly fracture related to the presence of the cavity. When a rod containing a cavity is subjected to a compressive stress pulse, part of the pulse is transmitted past the cavity and part is reflected. When the end of the rod is free, the cavity is subjected to a reflected tensile pulse which, if strong enough, can cause fracture. The existence of the cavity tends to weaken the rod since there is a reduction in the cross-sectional area and a stress concentration effect. Epoxy …

The Effects Of Repeated Loading On The Modulus Of Elasticity Of Concrete, Fidel T. Smith

Civil Engineering ETDs

Under present design methods, the modulus of elasticity is designated only with respect to the ultimate strength and the unit weight of concrete and is assumed constant throughout the life of the structure. The only provision made for change in the modulus of elasticity due to age, moisture content, type of loading or fatigue is to assume the weakest condition of the concrete. On elastic analysis the stress-strain relationship is assumed to be linear and the concrete is assumed to carry no tensile stress. In ultimate design procedures the concept of straight line distribution of stress is dropped and a …

Transient Response Of Linear Damped Lumped Spring-Mass Systems By Experimentally Derived Transfer Functions, Ralph W. Kelley

Electrical and Computer Engineering ETDs

In the field of mechanical shock testing, there are many instances where the responsive motions of linear undamped and lightly damped lumped spring-mass systems must be determined. If a model representing the system to be tested is available, it is possible to determine the responsive motion by several different approaches. Most of these methods require solving the differential equation of motion in some manner. Among the more common methods of solving the differential equation are the classical solution, the use of Laplace transforms, and various graphical techniques. All of these methods, however, require that a model of the system under …

Directional Effects Of Transient Radiation On Semiconductor Devices, Arthur C. Golubiewski

Electrical and Computer Engineering ETDs

The purpose of this study is to determine the directional effects of transient gamma radiation on electronic components. An analytic expression will be developed for radiation effect as a function of angle, and experiments will be described which verify the mathematical analysis.

A Mechanical Thevenin Equivalent Circuit Of A Separately Excited D.C. Motor, Hershel R. Lung

Electrical and Computer Engineering ETDs

This problem is concerned with the transient analysis of a DC machine with constant field excitation. By using the generalized circuit concept and Thevenin's Theorem applied to this concept, the transient behavior of this type of machine can be found from an analysis of a lumped circuit model of the machine. The lumped circuit model is a three port device and as such, the terminal equations describing the relationship between the difference and flow signals at the various ports are nonlinear. The nonlinear terms due to the products of signals in the terminal equations can be eliminated by requiring that …

Small Prolate Spheroidal Antenna In A Dissipative Medium., William Troy Cowan

Electrical and Computer Engineering ETDs

A perfectly conducting prolate spheroidal antenna immersed in a conducting medium is analyzed. It is assumed that the dimensions of the spheroid are small compared to a skin depth in the medium. A gain factor for the antenna as a receiver is computed as a function of the spheroid's axis ratio. The prolate spheroid is assumed to be excited by a circular filament of magnetic current located in the plane of the spheroid's minor axes to approximate excitation by a magnetic toroid. Expressions for the antenna's input admittance and effective length are derived. Some experimental results verifying the derivation of …