Mechanical Engineering Commons^™

Extracting The Grain Boundary Character/Free Energy Relationship From The Microstructure: Pure <100> And <111> Tilt Boundaries, Brent L. Adams, S. Costiner, D. Kinderlehrer, W. W. Mullins, Shlomo Ta'asan

Faculty Publications

This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-9632556. Analysis is described to extract the excess free energy of grain boundaries from the mesotexture of well-equilibrated polycrystalline samples. The approach is based upon the force and torque balances at triple junctions described in the classical work of Herring. The main advantage of the approach is that the free energy function is obtained over the full fundamental zone of grain boundary types. For the purposes of exposition, the method is described for specified two-parameter hypersurfaces in the fundamental zone for cubic polycrystals …

High-Pressure Oxidation Rates For Large Coal And Char Particles, James A. Mathias

Theses and Dissertations

The main objective of this study was to investigate the factors that influence the oxidation rate of large (five to eight millimeters in diameter) coal and char particles. To accomplish this, experiments were performed in which the gas temperature, gas velocity, particle size, partial pressure of oxygen, and total pressure were varied. The experiments were performed with the cantilever balance attachment and the high pressure controlled profile reactor.

Approximately 90 combustion experiments were performed with Pittsburgh, Utah Blind Canyon, and Wyodak-Anderson coal. These experiments were performed at atmospheric pressure with air and varied gas temperature, gas velocity, and particle size. …

Bounding Elastic Constants Of An Orthotropic Polycrystal Using Measurements Of The Microstructure, Brent L. Adams, M. J. Beran, T. A. Mason, Ted Olsen

Faculty Publications

We show how information about the elastic stiffness and compliance of an orthotropic polycrystal may be obtained from measurements of the statistical properties of the microstructure. We begin by discussing the statistical properties of the governing equations and the hierarchy that results when the equations are averaged. Perturbation solutions are obtained in terms of low-order statistical information. Using methods previously developed, we derive bounds for the elastic stiffnesses and compliances. A heirarchy of bounds is derived using the statistical information obtained from measurements of the microstructure. We discuss the methods used to obtain the correlation functions of the microstructure and …

The Development And Evaluation Of The Knife Finite Element, Brett W. Clark

Theses and Dissertations

This thesis presents the development and evaluation of the knife finite element which is a degenerate case of a hexahedral element. The knife connectivity is an artifact of automatic all-hexahedral mesh generators. Currently, knives are propagated to the surface of the mesh for removal. However since this disturbs the surface mesh, other alternatives are needed. This thesis investigates the option of leaving the knife connectivity in the mesh and treating it as a valid finite element. The shape functions and stiffness matrix for the knife element are derived and evaluated using theoretical and practical evaluations. It is concluded that the …

Grain-Boundary Structure Effects On Intergranular Stress Corrosion Cracking Of Alloy X-750, Brent L. Adams, Ted Olsen, N. Panayotou, Y. Pan

Faculty Publications

This work was supported by the Department of Energy under Grant No. DE-FG02-88ER 45355. TO was supported by the National Science Foundation during her 1993-94 stay at the Institute for Advanced Studies (Princeton) under grant DMS-9304580. The authors wish to acknowledge helpful discussion with Carol Nichols, John Hack, Gino Palumbo, Karl Aust, and Gary Was. It is well known that the properties and behavior of grain boundaries are strongly affected by local chemistry and atomic structure. This paper focuses on the mesoscale description of grain boundary structure (i.e. the five crystallographic degrees of freedom) and correlations with intergranular stress corrosion …

Experiments In The Coordinated Control Of An Underwater Arm/Vehicle System, Timothy W. Mclain, Stephen M. Rock, Michael J. Lee

Faculty Publications

The addition of manipulators to small autonomous underwater vehicles (AUVs) can pose significant control challenges due to hydrodynamic interactions between the arm and the vehicle. Experiments conducted at the monterey Bay Aquarium Research Institute (MBARI) using the OTTER vehicle have shown that dynamical interactions between an arm and a vehicle can be very significant. For the experiments reported in this paper, a single-link "arm" was mounted on OTTER. Tests showed that for 90-degree, two-second repetitive slews of the arm, the vehicle would move as much as 18 degrees in roll and 14 degrees in yaw when no vehicle control was …

Otter: A Testbed Submersible For Robotics Research, Tim Mclain, H H. Wang, R L. Marks, S D. Fleischer, D W. Miles, G A. Sapilewski, S M. Rock, M J. Lee, R C. Burton

Faculty Publications

Untethered, unmanned submersibles (UUSs) have the potential of becoming useful tools in nuclear reactor inspection and repair and waste-site cleanup and survey, in addition to subsea exploration. Classical "hand-in-glove" control methods used currently by tethered, remotely-operated vehicles (ROVs) are unsuitable for UUS systems which have, at best, limited communications. The Stanford Aerospace Robotics Laboratory (ARL) has joined with the Monterey Bay Aquarium Research Institute (MBARI) in a program to develop new methods of controlling UUS systems.

As a part of this effort, a submersible testbed has been built to test and develop new technologies that will make UUSs useful tools …

Characterization Of The Near-Interface Region Of Chemical Vapor Deposited Diamond Films On Silicon By Backscatter Kikuchi Diffraction, Brent L. Adams, K. Kunze, S. Geier, R. Hessmer, M. Schreck, B. Rauschembach, B. Stritzker

Faculty Publications

The lattice orientations near the interface of chemical vapor deposited diamond films on Si(001) have been studied by orientation imaging microscopy. This technique is based on the automated analysis of electron backscatter Kikuchi diffraction patterns. The electron beam has been scanned in discrete steps over the reverse side of the diamond film after having removed the substrate. The obtained data have allowed us to determine the texture and to visualize quantitatively the orientational arrangement of and among individual diamond crystallites in the near-interface region. A comparison with the orientation of the substrate has proved the existence of epitaxially nucleated grains. …

Characterization Of The Near-Interface Region Of Chemical Vapor Deposited Diamond Films On Silicon By Backscatter Kikuchi Diffraction, Brent L. Adams, K. Kunze, S. Geier, R. Hessmer, B. Rauschembach, M. Schreck, B. Stritzker

Faculty Publications

B.L.A. and K.K. gratefully acknowledge support under a Materials Research Group Award by the National Science Foundation No. DMR-9001278. Also the software support by Th. Bollmeier is greatly appreciated. The lattice orientations near the interface of chemical vapor deposited diamond films on Si(001) have been studied by orientation imaging microscopy. This technique is based on the automated analysis of electron backscatter Kikuchi diffraction patterns. The electron beamhas been scanned in discrete steps over the reverse side of the diamond film after having removed the substrate. The obtained data have allowed us to determine the texture and to visualize quantitatively the …

Inversion Of Light Scattering Measurements For Particle Size And Optical Constants: Theoretical Study, Matthew R. Jones, Bill P. Curry, M. Quinn Brewster, Keng H. Leong

Faculty Publications

We invert the Fredholm equation representing the light scattered by a single spherical particle or a distribution of spherical particles to obtain the particle size distribution function and refractive index. We obtain the solution by expanding the distribution function as a linear combination of a set of orthonormal basis functions. The set of orthonormal basis functions is composed of Schmidt-Hilbert eigenfunctions and a set of supplemental basis functions, which have been orthogonalized with respect to the Schmidt-Hilbert eigenfunctions by using the Gram-Schmidt orthogonalization procedure. We use the orthogonality properties of the basis functions and of the eigenvectors of the kernel …

Inversion Of Light Scattering Measurements For Particle Size And Optical Constants: Experimental Study, Matthew R. Jones, Keng H. Leong, M. Quinn Brewster, Bill P. Curry

Faculty Publications

Measurements of the light scattered by a sample contain information regarding the physical properties of the sample. Laser light-scattering measurements can be made unobtrusively in environments that are inaccessible to other types of measurements, so laser light-scattering techniques have become an important tool in aerosol research. The primary difficulty associated with using light-scattering techniques to determine aerosol particle properties is inverting the measurements or extracting the desired information from the measurements. In this study we use a 15-channel polar nephelometer to measure the light-scattering patterns of monodisperse polystyrene spheres. The light-scattering measurements are inverted, and the particle size distribution function …

Heterogeneity Of Intergranular Damage In Copper Crept In Plane-Strain Tension, Brent L. Adams, David P. Field

Faculty Publications

The authors wish to acknowledge support of this work by the Office of Basic Energy Sciences of the U. S. Department of Energy. An interface damage function (IDF), which statistically describes the area fraction of interface damage as a function of up to eight parameters defining crystallite interfaces, was determined for commercial purity copper specimens crept in plane strain tension. The IDF was determined from stereological parameters measured on plane sections cut through damaged specimens. The eight-dimensional space of the function was investigated by analyzing two-dimensional projections of the complete domain. Certain special interfaces were observed to damage preferentially. A …

Interface Cavitation Damage In Polycrystalline Copper, Brent L. Adams, David P. Field

Faculty Publications

The authors acknowledge the support of the Office of Basic Energy Sciences of the United States Department of Energy. Determination of an interface damage function (IDF) from a stereological procedure similar to that presented by Hilliard is described. The mathematical and experimental simplicity of the method is utilized in measuring an IDF for polycrystalline copper crept at 0.6T sub m under uniaxial tension. Whereas previous work focused on a five parameter description of the local state of a grain boundary, the domain of the IDF is increased to eight degrees of freedom in the present study to include the complete …

Experimental Measurement Of Rov Tether Tension, Tim W. Mclain, S M. Rock

Faculty Publications

In the undersea operation of a tethered ROV system, the pilot's ability to control precisely the ROV is often limited by disturbance forces generated by drag due to currents that act either directly on the ROV or indirectly on the ROV through the tether. The objective of this research, which was conducted at the Monterey Bay Aquarium Research Institute (MBARI), was to characterize the magnitude and dynamics of tether forces by measuring them during operation. To achieve this, a tether tension sensor and data logging system were developed. This system was used to measure the forces in the tether of …

Discussion Of The Representation Of Intercrystalline Misorientation In Cubic Materials, Brent L. Adams, Hans Grimmer, Junwu Zhao

Faculty Publications

BLA and JZ acknowledge the support of the Office of Basic Energy Science of the US Department of Energy under grant No. DE-FG02-88ER45355. Help from Stuart Wright with the figures is gratefully acknowledged. Salient features of various parameterizations of cubic-cubic misorientation are discussed. It is proposed that the quaternion representation of rotations, as a pair of antipodal points on the surface of a four-dimensional sphere, encompasses the most desirable properties of other proposed representations, viz rectilinearity, a closed form for the composition of successive rotations, and an equivalence between the Euclidean measure on its parameter space and the invariant measure …

Development, Simulation, And Validation Of A Highly Nonlinear Hydraulic Servosystem Model, Tim W. Mclain, E K. Iversen, C C. Davis, S C. Jacobsen

Faculty Publications

A highly accurate and predictive dynamic model of an electrohydraulic actuation system has been developed and verified. The accuracy of the model can be attributed to the inclusion of nonlinear representations of many system elements including hysteresis and saturation effects, orifice areas, piston damping, and flow forces. This level of accuracy makes the model a potentially valuable tool in the analysis and design of electrohydraulic actuation systems.

Design Of A Multiple Degree Of Freedom, Force Reflective Hand Master/Slave With A High Mobility Wrist, Tim Mclain, S C. Jacobsen, E K. Iversen, C C. Davis, D M. Potter

Faculty Publications

The Center for Engineering Design (CED) at the University of Utah has developed a force reflective, teleoperated multiple degree of freedom hand and high mobility wrist. This hand/wrist teleoperation system is targeted to perform dexterous manipulation and assembly tasks in an effort to approach the capabilities of a human. A first-stage prototype of this hand/wrist master/slave system, which is scheduled for laboratory demonstration in February of 1989, has nine actuated degrees of freedom in both the hand master and hand slave. This paper discusses elements of the design of this hand/wrist master and slave with particular emphasis on servo system …

Definition Of An Asymmetric Domain For Intercrystalline Misorientation In Cubic Materials In The Space Of Euler Angles, Brent L. Adams, Junwu Zhao

Faculty Publications

The authors wish to acknowledge the support of the United States Department of Energy, Office of Basic Energy Sciences, under grant No. DE-FG02-85ER45203. Critical review by Professor Dorian Hatch of the Physics Department at Brigham Young University is gratefully acknowledged. A new asymmetric domain for intercrystalline misorientation is defined in the space of Euler angles for materials exhibiting cubic (Oh point-group) lattice symmetry. The invariant measure for this new domain is nearly constant; this is in significant contrast to the previous domain defined by MacKenzie [Biornetrika (1958), 45, 229-240]. Distribution functions in the misorientation can now be represented with greater …

Flexible Engineering Software: An Integrated Workstation Approach To Finite Element Analysis, Brant Arnold Ross

Theses and Dissertations

One obstacle preventing more engineers from using finite element analysis (FEA) is the difficulty of transferring data between steps in the modeling process. A Fortran computer program, Rosetta.BYU, has been developed to open data paths between finite element preprocessors (mesh generators) and finite element analysis programs, using a custom data structure. It accepts neutral data files, Version 2.0 IGES data files, and Movie.BYU files for input/output. An application of Rosetta is described. A general workstation manager program, Davinci.BYU, is reviewed that provides a support layer between the engineer and the operating system, organizes software and data files, and facilitates on-line …

Atomic Simulation Of The Al2 (111) (110) Edge Dislocation In Alpha-Iron, Brent L. Adams, P. C. Gehlen, J. P. Hirth, R. G. Hoagland

Faculty Publications

The authors are pleased to acknowledge: the support of this research by the National Science Foundation under Grant DMR 74-21243 and by the provision of computer time by The Ohio State University and by Battelle Columbus Laboratories; and helpful comments on the manuscript by V Vitek. Computer simulation is used to obtain the plane strain and non-plane strain equilibrium core structures for the a/2 <111> {110} edge dislocation in alpha-iron as modelled by the Johnson potential. The methods of the integral formulation of anisotropic linear eleasticity theory are employed in the analysis. Flexible core boundary methods reveal that positive volume expansions …

Sensitivity Of Process Variables On Rigid Polyurethane Foaming, Bruce A. Pugsley

Theses and Dissertations

Inadequate understanding and/or control of the polyurethane rigid foam process normally requires five to ten percent overpack of cavities to obtain correct fill and foam characteristics. This practice of overpacking has resulted in excessive waste and cost.

An Improved Fission Product Pressure Model For Use In The Venus-Ii Disassembly Code, Ray Leland Jensen

Theses and Dissertations

The world's growing need for safe, reliable, and long-term energy sources has intensified the research being conducted in the development of nuclear power. The operation of power reactors is contingent upon the continued availability of the fissile material required to maintain a critic a l reactor. The only naturally occuring fissile material is an isotope of uranium, U-235, which only accounts for 0.76 percent of the uranium that is mined. Due to the relative scarcity of this important fissile material it is estimated the United States' sources of economically recoverable fissile material will be delinquished with in about twenty-five years.^1

Steady-State Fluidics: Computer-Aided Analysis Of Analog Fluidic Circuits By Use Of Experimentally Determined Characteristic Curves, Raymond P. Martin Jr.

Theses and Dissertations

One of the fundamental tasks confronting engineers is the transmission and control of energy. The engineer, faced with this requirement and influenced by details of a specific, situation, his education and experience, and the customer's desires, will probably select a mechanical, electrical, or electro-mechanical system. Often a better choice exists—the use of a fluid power system. Fluid power systems employ pressurized fluids, liquids and/or gases, to transmit and control energy. Hydraulic systems use liquids, usually special oils or treated water. Pneumatic. systems use air or other gases. Both types are versatile and find a wide range of application.

Steady State Fluidics: The Static Matching Of Fluidic Amplifiers And Loads, Frank J. Redd

Theses and Dissertations

"Fluidics" is the title applied to a relatively new technology which is concerned with the control of fluid power and the processing of information through the use of the fluid mechanical properties of the fluid medium itself. The absence of moving parts and the relatively low sensitivity to enviromental conditions suggest the probability that fluidic systems will prove to be faster and more reliable than the mechanically controlled (valves, diaphragms, springs, etc.) fluid systems which they are designed to replace.

Alcohol Assisted Hydrocarbon Fuels: A Comparison Of Exhaust Emissions, Power Output And Fuel Consumption Using Static And Dynamic Engine Test Facilities, Dwight J. Bushnell

Theses and Dissertations

America’s energy crunch— something new for a country that has been used to great affluence. America’s smog— an eye stinging, lung burning situation which the Environmental Protection Agency has "promised" to rectify. These are two outstanding problems that face the engineer and scientist of today. The end of the era of cheap gasoline has brought the beginnings of a quiet revolution to Detroit: an improvement in the efficiency, economy and emission level of the American automobile. Word has penetrated to the automotive engineers that the emissions level, fuel economy and automobile safety are the prime design considerations for the automobile …

Determination Of The Most Economically Feasible Method For High Volume Machining Of A Discharge Port In A Powder-Metal Compressor Cylinder, Perry W. Carter

Theses and Dissertations

The purpose of this study was to ascertain the most economically feasible method for high volume machining of a discharge hole in a power metal compressor cylinder.

Transient Convective Heat Transfer In Closed Containers During And After Gas Injection, Jennings Donell Means

Theses and Dissertations

This dissertation presents experimental data correlations for the spatially - averaged convective heat transfer coefficient for thin walled closed containers during and after gas injection. The different modes of heat transfer were identified, and correlations were made for each. Correlations are presented for the injection period, post-top injection, post-bottom injection, post- tangential, post-radial injection, and post-ejection heat transfer for various tank geometries. Of special significance are the very high heat transfer rates that were shown to be present in some cases immediately after injection. Heat transfer rates were shown to be, for a short period, up to almost two orders …

Analysis Of Heat Generation And Temperature In High Speed, High Temperature Bearing Balls, Hans R. Ringger

Theses and Dissertations

This thesis reports an investigation of the generation of heat on, and the prediction of temperature of high-speed, dry-film lubricated, stainless steel bearing balls.

The Design And Analysis Of An Electro-Pneumatic Signal Converter, Richard K. Thornton

Theses and Dissertations

In the field of process control it is desirable to study dynamic characteristics such as frequency response and distortion when determining just how equipment is to be controlled. Pneumatic controllers, transmitters, control valves, etc., all have dynamic behaviors which can be expressed mathematically as transfer functions. Each component plays an important role in determining the entire system behavior. Frequency response is one technique used in developing a component’s transfer function. By driving a device with a sinusoidal signal of fixed amplitude and frequency the output amplitude and phase shift are measured and compared with that of the input. Varying the …

Finite Conductance Element Method Of Conduction Heat Transfer, E. Clark Lemmon

Theses and Dissertations

One of the basic goals in engineering is to formulate models which will provide a means for analytically predicting observed phenomenon. For some time, the partial differential equations describing the steady state and transient conduction of heat within a solid have been available. However, the straight forward use of these equations is often restricted due to the surface geometry of the solid. If the surface geometry is at all irregular, exact solutions will in general not exist. In that case, a solution is sought by some approximate numerical technique. The two techniques most often used are the finite difference method …