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On The Degradation Of Lubricating Grease, Asghar Rezasoltani
On The Degradation Of Lubricating Grease, Asghar Rezasoltani
LSU Doctoral Dissertations
A comprehensive literature review on physical and chemical degradation monitoring and life estimation models for lubricating greases is presented in chapter one. Degradation mechanisms for lubricating grease are categorized and described, and an extensive survey of the available empirical and analytical grease life estimation models including degradation monitoring standards and methods are presented. In chapter two, irreversible thermodynamic theory is employed to study the mechanical degradation of lubricating grease. A correlation between the mechanical degradation and entropy generation is established and the results are verified experimentally using a rheometer, a journal bearing test rig, and a modified grease worker machine. …
Design, Fabrication And Thermomechanical Testing Of A Vertical Bimorph Sensor In The Wafer Plane, Madhulika Sathe
Design, Fabrication And Thermomechanical Testing Of A Vertical Bimorph Sensor In The Wafer Plane, Madhulika Sathe
LSU Master's Theses
A bimetallic recurve device was designed, fabricated and tested as a temperature sensor. The device is to be used for sensing temperatures up to 300 C inside oil wells for downhole condition monitoring. Continuous downhole measurements at high temperatures and pressures are required to monitor conditions downhole instruments are exposed to during use. Currently mercury thermometers and resistive temperature detectors (RTD) are used for downhole temperature measurements. Microsensors have potential application downhole, due to their small size and inherent robustness. The principle of a bimetallic beam was used to measure temperature. A bimetallic beam deflects with changes in temperature due …
Active Control Of Thermoacoustical Instabilities., Daniel Ulises Campos-Delgado
Active Control Of Thermoacoustical Instabilities., Daniel Ulises Campos-Delgado
LSU Historical Dissertations and Theses
This dissertation presents some advances in active control of thermoacoustic instabilities in combustion chambers. Large-size gaseous and liquid fueled swirl stabilized combustors were used during the studies. Active control was implemented using different types of actuators. Proportional (loudspeakers and fuel valves) and discrete actuators (open-close automotive fuel injectors) were investigated. Acoustic and fuel modulation control were successfully applied. In large-scale combustors, flame stabilization techniques such as swirl add three dimensional characteristics to the flow. Moreover, the induced turbulence creates highly nonlinear interactions in the system. Thus, in order to capture these characteristics nonlinear partial differential equations have to be used. …
Effects Of Microstructure And Crystallographic Texture On Yield Behavior Of Aluminum-Copper-Lithium 2195 Plate., Karen Elizabeth Crosby
Effects Of Microstructure And Crystallographic Texture On Yield Behavior Of Aluminum-Copper-Lithium 2195 Plate., Karen Elizabeth Crosby
LSU Historical Dissertations and Theses
The focus of this research is to study the effects of deformation and aging on the yield behavior of precipitation-hardened Al-Cu-Li alloys, specifically AI-Cu-Li 2195 plate. Al-Cu-Li 2195 is a relatively new and exceptionally strong, yet lightweight aluminum alloy. Experimental methods applicable to mechanical/structural engineering and materials science problems provide the means for understanding the interrelation of deformation, microstructure, and crystal orientation (texture) as they affect the mechanical properties of crystalline materials. Yield strength is a vital mechanical property in that it defines the boundary of stress that may be applied to a part before a permanent, in some cases, …
Well Integrity Mechanism, Failure, And Testing In Shallow Marine Sediments., Desheng Zhou
Well Integrity Mechanism, Failure, And Testing In Shallow Marine Sediments., Desheng Zhou
LSU Historical Dissertations and Theses
The leak-off test (LOT) is an in-situ method for testing casing shoe integrity in a well. It is used to evaluate the cement and formation integrity relative to the well plan specifications. The results determine whether any remedial cementing or corrective actions are required and are a basis for planning future wells in the area. Typical analysis of LOTs assumes an elastic wellbore and involves identification of linear trends on the recorded plots. However, LOTs recorded in shallow marine sediments (SMS) are inherently nonlinear and their analysis is a problem. Starting from the analyses of shallow soil properties, LOT plots, …
Characterization Of Solidification/Stabilization Of Chromium Wastes In Cement Matrix., Aijun Zhang
Characterization Of Solidification/Stabilization Of Chromium Wastes In Cement Matrix., Aijun Zhang
LSU Historical Dissertations and Theses
A cement-based solidification/stabilization (S/S) system of Cr wastes treatment has been studied in this program. A combination of the two techniques; namely reduction of Cr(VI) to Cr(III) and simultaneous immobilization within a cement matrix, has been found to be effective and practical to treat Cr wastes. Cr(VI) can not be easily and effectively-immobilized in the S/S system unless being reduced to Cr(III). Ferrous compounds are used as reducing reagents. The reduction not only removes the toxic Cr(VI) species but also results in the low-solubility precipitation of (CrxFe 1-x) (OH)3(s) in the S/S system. Long-term and short-term samples were tested through …
Flexural Creep Analysis Of Recycled Polymeric Structural Elements., Jose Noe Martinez-Guerrero
Flexural Creep Analysis Of Recycled Polymeric Structural Elements., Jose Noe Martinez-Guerrero
LSU Historical Dissertations and Theses
A structural product made of recycled plastics in standard sections similar to dimensional lumber is referred to as plastic lumber. The recycled plastics used in the manufacture of these members include high density polyethylene, polyethylene terephthalate and polystyrene. Plastic lumber is a viscoelastic material possessing mechanical properties that are time and temperature dependent. This structural product is currently used primarily in non-load-bearing and low-end structural applications because of the non availability of engineering data and concerns about its creep behavior. Creep, which is the time dependent deformation under constant stress, is high for plastic lumber and is temperature sensitive. A …
Diagnosis Of Poor Pdc Bit Performance In Deep Shales., John Rogers Smith
Diagnosis Of Poor Pdc Bit Performance In Deep Shales., John Rogers Smith
LSU Historical Dissertations and Theses
This study was performed to diagnose the cause of poor PDC bit performance in deep, overpressured shales. Deep, overpressured wells account for a disproportionate share of all drilling costs, about 27 percent. The effect of bit performance on this cost is significant, about $2.9 billion annually in overpressured formations alone. Bit performance in deep, overpressured formations when using water-based muds is especially poor, adding at least \$500 million annually to worldwide drilling costs. This problem is described as the slow drilling shale problem and is shown to exist worldwide. Potential causes of this problem identified in the technical literature include …
Perturbed Flows In Ribbed Ducts., Pradipta Kumar Panigrahi
Perturbed Flows In Ribbed Ducts., Pradipta Kumar Panigrahi
LSU Historical Dissertations and Theses
Turbulent characteristics of a reattaching shear layer is important in gas turbine blade cooling, dump combustors, airfoil separation, internally ribbed heat exchangers, and in electronic cooling. In this study flow past a surface mounted rib encountered in the internal coolant channels of gas turbine blades and internally ribbed heat exchangers is studied. The main objectives of this investigation are: (1) to develop improved methods of coherent structures analysis, (2) to examine the spectral characteristics and length scale, (3) to investigate the types of turbulent motions using octant analysis, (4) to study the flow structures and kinetic energy budget for both …
Analysis Of Taper-Taper Adhesive-Bonded Joints In Composite Plates Under Tension And Cylindrical Bending., Jack Elwin Helms Jr
Analysis Of Taper-Taper Adhesive-Bonded Joints In Composite Plates Under Tension And Cylindrical Bending., Jack Elwin Helms Jr
LSU Historical Dissertations and Theses
A taper-taper adhesive-bonded joint between two composite plates has been analyzed under tension and cylindrical bending. Two tension models were derived. The first model was based on mechanics of materials and the second model used laminated plate theory and shear correction factors. For the mechanics of materials model the condition of plane strain was assumed for the adherends and adhesive. Average stresses were used in the adherends and point-wise stresses were used in the adhesive. The model derived consisted of four second-order ordinary differential equations with variable coefficients. The adherends were characterized by the extensional Young's modulus. The equations were …
Tribological Behavior Of Duplex Nitrogen Diffusion/Dlc Coating Treatments., Yan Liu
Tribological Behavior Of Duplex Nitrogen Diffusion/Dlc Coating Treatments., Yan Liu
LSU Historical Dissertations and Theses
Diamond-like carbon (DLC) coatings have high potential for developing advanced tribological systems and the overall objective of the present research is to provide a framework to theoretically design and experimentally develop and study such systems of interest. The present research concentrates on the following specific aspects: the fundamental wear mechanism of DLC coatings; finite element (FE) modeling to understand the stress distribution in coating/substrate system under indentation and friction; and the influence of graded interface on the tribological behavior of DLC coatings. The experimental results showed that DLC films possess low friction coefficient ($f\sb{init}$: 0.12-0.20, $f\sb{fin}$: 0.06-0.08) and low wear …
Performance Of Composite Piping Systems: Thermal, Fire Endurance, And Joining Characteristics., Michael Andre Stubblefield
Performance Of Composite Piping Systems: Thermal, Fire Endurance, And Joining Characteristics., Michael Andre Stubblefield
LSU Historical Dissertations and Theses
Composite piping systems are becoming the "System of Choice" in many applications previously the domain of metallic piping systems. For full acceptability and usage of these composite piping systems, new innovative approaches must be developed. Three areas of development are addressed; (i) thermal efficiency, (ii) fire endurance, and (iii) joining techniques. In the development of the energy conserving composite pipe, the thermal contact resistance acts as an additional insulating layer. A model and device to predict and measure the contact resistance for a pipe system has been developed. A corrugated layer, which acts as an enhanced contact resistance layer, forms …
Development Of A Prototype Computer-Assisted Well Control System For Deep Ocean Drilling Environments., Orville Allen Kelly
Development Of A Prototype Computer-Assisted Well Control System For Deep Ocean Drilling Environments., Orville Allen Kelly
LSU Historical Dissertations and Theses
An advanced prototype computer-assisted deep water drilling well control system was developed using process control technology. The goal of the system was to improve rig safety by reducing the potential for surface and underground blowouts through providing enhanced bottom hole and casing seat pressure control during the well kill process. The system developed is capable of full computer control of the fluid pump and drilling choke control functions during normal well control operations. The system provides computer-assistance in collecting and curve fitting slow circulation rate pump pressure data, in developing a well kill program (kill sheet), and in detecting anomalies …
The Recycling Potential Of Out-Of-Service Utility Poles For Engineered Wood Products., Han Roliadi
The Recycling Potential Of Out-Of-Service Utility Poles For Engineered Wood Products., Han Roliadi
LSU Historical Dissertations and Theses
This study on the recycling potential of out-of-service poles for use in engineered wood products involved determination of basic properties of used southern pine (Pinus sp.) utility poles and also manufacture of glued-laminated beams from these poles. Most of the defect-free portions of 25-year treated poles still retained adequate strengths comparable to those of freshly treated poles and untreated southern pine. Creosote contents, however, diminished with pole ages. The reduction in creosote content was correlated with lower decay resistance, poorer dimensional stability, and lower lumber recovery, but better gluability. The spectrometry method for creosote content determination was explored as an …
Feature-Based Models For Three-Dimensional Data Fitting., Gregory Todd Dobson
Feature-Based Models For Three-Dimensional Data Fitting., Gregory Todd Dobson
LSU Historical Dissertations and Theses
There are numerous techniques available for fitting a surface to any supplied data set. The feature-based modeling technique takes advantage of the known, geometric shape of the data by deforming a model having this generic shape to approximate the data. The model is constructed as a rational B-spline surface with characteristic features superimposed on its definition. The first step in the fitting process is to align the model with a data set using the center of mass, principal axes and/or landmarks. Using this initial orientation, the position, rotation and scale parameters are optimized using a Newton-type optimization of a least …
A Micro-Mechanical Fatigue Damage Model For Uni-Directional Metal Matrix Composites., Rainer Echle
A Micro-Mechanical Fatigue Damage Model For Uni-Directional Metal Matrix Composites., Rainer Echle
LSU Historical Dissertations and Theses
A micro-mechanical damage model for high cycle fatigue loading based on thermo-dynamical principles is developed for uni-directional continuous fiber reinforced metal matrix composites. The model uses a micro-mechanical based theory to predict the fatigue damage evolution in the individual constituents of the composite material, namely the fibers and the matrix, from which the overall fatigue damage evolution in the composite is obtained. The micro-mechanical analysis is performed for each individual constituent using stress and strain concentration tensors based on the Mori-Tanaka method. A fatigue damage criterion based on thermo-dynamical principles is developed and applied to each of the constituents. Fatigue …
Development Of An Analysis System For Discontinuities In Rigid Airfield Pavements., Michael Ivan Hammons
Development Of An Analysis System For Discontinuities In Rigid Airfield Pavements., Michael Ivan Hammons
LSU Historical Dissertations and Theses
The response of the rigid pavement slab-joint-base structural system is complex, and accurately predicting the response of such a system requires a significant degree of analytical sophistication. The research reported in this dissertation has defined some essential features required to adequately model the system and has demonstrated a technique to develop a comprehensive three-dimensional (3D) finite element model of the rigid pavement slab-joint-foundation structural system. Analysis of experimental data from the 1950s confirms that explicit modeling of dowels is not required to model the structural response of the system. Additional experimental data gathered as a part of this research indicates …
Improved Method For Selecting Kick Tolerance During Deepwater Drilling Operations., Shiniti Ohara
Improved Method For Selecting Kick Tolerance During Deepwater Drilling Operations., Shiniti Ohara
LSU Historical Dissertations and Theses
One of the most critical aspects in the design of oil and gas wells is the selection of the depths at which steel casing is set. As the length of open borehole increases, the risk of formation fracturing during drilling operations increases. Formation fracture often leads to an underground blowout that can be very expensive to control. Because of the special problems involved in drilling deepwater well, accurately measuring the risk of formation fracture is essential. A calculated parameter called "kick tolerance" is often used to measure this risk. In this study, improved computer software specifically designed for computing kick …
Experimental Investigation Of Wall And Inertial Effects On A Disk Sedimenting At Low Reynolds Number., Joe Wade Pulley
Experimental Investigation Of Wall And Inertial Effects On A Disk Sedimenting At Low Reynolds Number., Joe Wade Pulley
LSU Historical Dissertations and Theses
Measurements have been made of the drag on a thin disk of diameter d moving broadside through a liquid of viscosity $\mu$ and density $\rho$. The liquid is bounded on the outside by a cylindrical tube, diameter D, which is coaxial with the disk. The geometrical parameter $\xi$ = d/D ranges from 0.0189 to 0.112. The Reynolds number Re = $\rho$Ud/$\mu$ ranges from 0.0167 to 6.89. When the measured values are extrapolated to Re = 0, the results agree with the calculations of Shail and Norton. When extrapolated to $\xi$ = 0, the results agree with the matched-asymptotic series solution …
Mobilization Of A Hydrophobic Organic Compound Using Surfactant For Soil Washing., Minwen Liu
Mobilization Of A Hydrophobic Organic Compound Using Surfactant For Soil Washing., Minwen Liu
LSU Historical Dissertations and Theses
Soil washing using surfactants is a promising alternative for the conventional pump-and-treat method of removing hydrophobic organic compounds. The interactions and the transport of the chemicals have been studied by batch and column experiments. Sodium dodecylsulfate (SDS), an anionic surfactant, and anthracene, a hydrophobic organic, were chosen as the representative surfactant and contaminant, respectively. Fine sand and native soil were used as formation media. The experimental results indicated that the maximum loss of SDS on native soil from the solution was observed when the aqueous SDS concentration was in the region of the critical micelle concentration, and this loss was …
A Non-Proportional Cyclic Plasticity Model For Metals With Ratchetting Effects., Srinivasan Madras Sivakumar
A Non-Proportional Cyclic Plasticity Model For Metals With Ratchetting Effects., Srinivasan Madras Sivakumar
LSU Historical Dissertations and Theses
The path-dependent and nonlinear behavior of metallic materials subjected to cyclic loading is modelled using the proposed hardening rule. It uses mainly two surfaces, a yield and a limit surface and includes the memory effects through a separate surface called the memory surface which is obtained from a maximum stress criterion. The model considers the facts that the motion of the center of the yield surface in the stress space is mainly governed by the direction of the deviatoric stress rate and that the uniqueness of the solution requires nesting of the two surfaces. The model proposed satisfies both conditions …
A Study Of Heat Transfer In Rotary Desorbers Used To Remediate Contaminated Soils., Charles Alan Cook
A Study Of Heat Transfer In Rotary Desorbers Used To Remediate Contaminated Soils., Charles Alan Cook
LSU Historical Dissertations and Theses
A comprehensive heat transfer model is developed which describes heat transfer phenomena in rotary desorbers. This model predicts the temperatures of the solids bed and gases in the desorber and the rate of water evaporation from the solids. Emphasis is placed on describing the heat transfer process between the rotating wall of a desorber and the adjacent bed of solids. A heat-balance integral method is used to model heat conduction from the wall to adjacent wet bed particles. This solution includes the effects of water evaporation near the wall and a thermal contact resistance between the wall and the first …
Optimal Design Of A Fully Parallel Robot Manipulator., Chan Soo Kim
Optimal Design Of A Fully Parallel Robot Manipulator., Chan Soo Kim
LSU Historical Dissertations and Theses
Optimal design of a six degrees-of-freedom, fully parallel manipulator, called a Stewart platform is investigated. In order to optimize the mechanism, new performance measures are introduced since use of the previous methods suffer from lack of physical meaning due to dimensional inhomogeneity. To overcome the dimensional inhomogeneity problem, an Euclidean norm definition of each output space with homogeneous dimension is used to find input-output norm relation. As a result, four sets of eigenvalues are obtained which characterize translational and rotational velocity, force and torque, and position and orientation accuracy. From the four sets of eigenvalues, four determinant measures are defined, …
Synergistic Control Of N-Body Computer Generated Robots., Don Alan Iglehart
Synergistic Control Of N-Body Computer Generated Robots., Don Alan Iglehart
LSU Historical Dissertations and Theses
This project uses N-Body computer generated robots to investigate the fundamental problem of synergistic control of robots. This facility is important in an automated manufacturing environment and relates directly to the expanding field of study involving nonlinear systems. Experiments are performed utilizing this force controlled model to investigate nonlinear control problems using one of the techniques advanced. The principal results of this work are summarized: (1) A new simulation package is developed which uses Lagrange equations with multipliers to model two dimensional user defined robots. Three dimensionalization and parallelization are discussed and a dynamic optimization algorithm is introduced for regulating …
Dynamic Response Of An Electron Storage Ring Magnet., Shahriar Jahanian
Dynamic Response Of An Electron Storage Ring Magnet., Shahriar Jahanian
LSU Historical Dissertations and Theses
A combined experimental and numerical methodology was employed to investigate the dynamic response of the electron storage ring dipole magnets located in the Center for Advanced Microstructural Devices (CAMD) at Louisiana State University (L.S.U.). The magnet are highly anisotropic and can not be analysed for dynamic response without knowledge of the effective elastic properties. The theory of wave propagation in conjunction with finite element analysis was used to determine the variation of the effective modulus of elasticity magnets in question. The structure of the magnet was modeled with NASTRAN. A theoretical analysis was performede that supported the experimental variation of …
Fatigue Failure Of Composite Bolted Joints., Paul Douglas Herrington
Fatigue Failure Of Composite Bolted Joints., Paul Douglas Herrington
LSU Historical Dissertations and Theses
The objective of this study is to investigate the fatigue behavior of a double-lap, bolted composite joint. The material used for all tests is a quasi-isotropic graphite-epoxy laminate. Prior to fatigue testing, monotonic loading tests were performed in order to establish the important fundamental properties of friction coefficients and the ultimate bearing strength of composite joints. Proper design of friction type bolted joints for composite materials accounts for the force transmitted through friction between the clamped materials. This consideration requires knowledge of the coefficient of friction between the mating surfaces of the bolt, or washer, and the composite material. In …
An Adaptive Differencing Scheme For Elliptic Flows., Therese Estelle Rhodes
An Adaptive Differencing Scheme For Elliptic Flows., Therese Estelle Rhodes
LSU Historical Dissertations and Theses
This thesis deals with the formulation of a computationally efficient multiple-grid adaptive differencing (MAD) scheme for two-dimensional elliptic flow and heat transfer problems. This algorithm equidistributes a measure of the error by using higher order differencing schemes locally in adaptively determined high error-estimate regions. The third-order accurate QUICK scheme is used in regions of high error estimate which are dynamically flagged on the basis of a preliminary first order upwind solution. Boundary conditions for the flagged regions are taken from the preliminary upwind solution. Multigrid type calculations are performed. Three multiple-grid schemes are developed. In the first scheme, MAD1-WFDS, the …
Formation And Destruction Of Nitric Oxide In Fuel-Rich Combustion: Reburning., Thomas Emmett Burch
Formation And Destruction Of Nitric Oxide In Fuel-Rich Combustion: Reburning., Thomas Emmett Burch
LSU Historical Dissertations and Theses
The effect of fuel type on reburning of a simulated flue gas containing 1000 ppm of NO is studied. Stable nitrogen species concentrations are provided for reburning experiments with five fuels in a premixed, laminar flow reactor. The reactor was operated at atmospheric pressure and gave a maximum gas temperature of approximately 1100$\sp\circ$C for a residence time near 0.2 seconds. The experimental facility used to collect this data is described including a novel coal feeding device. A new gas chromatographic method used to analyze fixed-nitrogen species is described. For each of the five fuels, the fixed-nitrogen speciation as a function …
The Combustion Of Linear Droplet Arrays In A Coaxial Convective Flow., Jeng-Syan Tsai
The Combustion Of Linear Droplet Arrays In A Coaxial Convective Flow., Jeng-Syan Tsai
LSU Historical Dissertations and Theses
As approximations for spray-combustion processes, a series of increasingly sophisticated numerical models has been developed to simulate the combustion of linear droplet arrays in a co-axial, convective flow. Common to all of the models is an embedded grid, developed to increase computational accuracy. The first and simplest model is potential flow model (for Re $\to$ $\infty$). The flow is assumed to be ideal and infinitely-fast kinetics (flame sheet assumption) represent the combustion. The results show that the instantaneous droplet burning rates are increased as the droplet spacing is increased, and the burning rates of droplets tend asymptotically to smaller values …
Modeling Flat Flames Burning Chlorinated Methanes In A Methane/Air Environment., Gary Peyton Miller
Modeling Flat Flames Burning Chlorinated Methanes In A Methane/Air Environment., Gary Peyton Miller
LSU Historical Dissertations and Theses
A numerical model was developed to simulate flat flames burning chlorinated methanes in a methane/air environment. The model uses a reaction mechanism containing 341 reactions and 58 species. A time-stepping solution with linearized source terms and a strict convergence criteria had to be developed to allow for convergence of the conservation equations. Simulations of ten flames were made, five simulations of dichloromethane/methane/air flames, and five simulations of carbon tetrachloride/methane/air flames. For each fuel type, simulations were performed at a constant molar Cl/H ratio of 0.3 for a stoichiometric flame, a fuel-rich flame, and a fuel-lean flame. The other simulations were …