Engineering Commons^™

Synthesis And Study Of Polymers Containing Inorganic Ions, Lateef Aderoju Ibikunle-Sofoluwe

Theses

Cupric and ferrous polyacrylates have been prepared and studied. It was thought that partial reduction of Cu²⁺ or Fe³⁺ or oxidation of Cu⁺ or Fe²⁺ might result in semiconducting behavior but no such effect has been observed. Nevertheless, the results obtained are of considerable interest. Quantitative gravimetric and volumetric studies of cupric polyacrylate precipitation from varying molar ratios of cupric chloride and sodium polyacrylate in aqueous solution have shown that the only product formed is Cu(PA)₂ (Where PA represents an acrylate mer in polyacrylate). The insolubility of the product indicates that much of the Cu …

The Fractal Dimension As A Measure Of The Roughness Of Rock Discontinuity Profiles, Y. H. Lee, J. R. Carr, David J. Barr, Charles J. Haas

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

An important factor in the analysis of deformation and failure of rock masses along discontinuities is the roughness of the jointing surfaces. The fractal dimension is proposed as a method of objectively quantifying the roughness profile of such discontinuities. With this method much less engineering judgement and experience are required in determining the surface roughness,sb than is required for other methods such as the widely used joint roughness coefficient (JRC) suggested by the International Society for Rock Mechanics [1] (Int. J. Rock. Mech. Min. Sci. & Geomech. Abstr. 15, 319-368, 1978). The fractal dimension, suggested by Mandelbrot [2] (Fractals-Form, Chance …

Comparison Of Digital Controllers Used In Magnetic Suspension And Balance Systems, William Allen Kilgore

Mechanical & Aerospace Engineering Theses & Dissertations

Dynamic systems that were once controlled by analog circuits are now controlled by digital computers. Presented is a comparison of the digital controllers presently used with magnetic suspension and balance systems. The overall response of the systems are compared using a computer simulation of the magnetic suspension and balance system and the digital controllers. The comparisons include responses to both simulated force and position inputs. A preferred digital controller is determined from the simulated responses.

The Effects Of Bending On The Strain Distributions In A Stiffener-Skin Interface Region, Osvaldo F. Lopez

Mechanical & Aerospace Engineering Theses & Dissertations

An analytical and experimental study to assess the effect of bending on the adhesive strain distributions in a stiffener-skin interface region is described. A one-dimensional beam analysis is derived using a variational approach. Parametric studies are conducted to assess the effects of stiffener, skin, and adhesive thickness and adhesive material nonlinearity on the adhesive layer extensional and shear strain distributions subjected to applied bending. Two experimental methods of measuring through-the-thickness extensional strains in an adhesive are investigated. One method involves measuring the changes in the resistance of a composite strain sensor subjected to applied tension and compression loads. The second …

Application Of Shape Sensitivity Analysis For Computation Of Transient Free-Surface Flows, Frank Nicolas Michel

Mechanical & Aerospace Engineering Theses & Dissertations

Shape sensitivity analysis is introduced into a numerical scheme simulating a transient free-surface flow and applied to the case of a fluid advancing through a bed of cylinders. For this incompressible Newtonian flow, viscous forces are dominant. A penalty function finite element formulation is used to solve the problem. Coordinates of nodes on the moving boundary are chosen as design variables and an analytical formulation of the gradient of the finite element algebraic system, with respect to these variables, is derived.

In a numerical example, the results obtained with and without sensitivity analysis are compared. The efficiency and accuracy of …

Determinations Of Molecular Weight And Molecular Weight Distribution Of High Polymers By The Rheological Properties, Joan Y. Z. Huang

Mechanical & Aerospace Engineering Theses & Dissertations

Several methods are reviewed by which the molecular weight (MW) and molecular weight distribution (MWD) of polymeric material were determined from the rheological properties. A poly (arylene ether) polymer with six different molecular weights was used in this investigation. Experimentally measured MW and MWD were conducted by GPC/LALLS (Gel Permeation Chromatography/Low Angle Laser Light Scattering), and the rheological properties of the melts were measured by a Rheometric System Four rheometer. It was found that qualitative information of the MW and MWD of these polymers could be derived from the viscoelastic properties, with the methods proposed by Zeichner and Pate1, and …

Stability Design Of A Slender Column With Curved Longitudinal Stiffeners, Mark S. Lake

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis presents the results of a stability design study of a slender column with curved longitudinal stiffeners for large space structure applications. The stiffened column concept is attractive because it allows the buckling load of a slender column to be increased at a fairly low cost in increased mass, and at no change in the column packaged size. Linear stability analyses are performed using a "linked-plate" representation of the stiffeners to determine stiffener local buckling stresses. Results from a set of parametric analyses are used to determine an approximate explicit expression for stiffener local buckling in terms of its …

Investigating The Method Of Structural Topological Variations For Sensitivity Analysis And Design Optimization, Niki A. Mehta

Mechanical & Aerospace Engineering Theses & Dissertations

The method of structural topological variations is a newly developed technique for analysis of frame structures. It provides a novel method that completely avoids formulating and solving simultaneous equations, required in the finite element displacement method. The principal objective of this thesis is to investigate the method of topological variations as a possible design tool and study its applicability in the sensitivity analysis and in the process of design optimization.

A computer code was developed for this method to obtain its comparative performance against the finite element displacement method. For analysis of large structures involving frequent local modifications, the method …

Global/Local Stress Analysis Of Composite Structures, Jonathan B. Ransom

Mechanical & Aerospace Engineering Theses & Dissertations

A method for performing a global/local stress analysis is described and its capabilities are demonstrated. The method employs spline interpolation functions which satisfy the linear plate bending equation to determine displacements and rotations from a global model which are used as "boundary conditions" for the local model. Then, the local model is analyzed independent of the global model of the structure. This approach can be used to determine local, detailed stress states for specific structural regions using independent, refined local models which exploit information from less-refined global models. The method presented is not restricted to having a priori knowledge of …

Explicit And Implicit Calculations Of Turbulent Cavity Flows With And Without Yaw Angle, Guan-Wei Yen

Mechanical & Aerospace Engineering Theses & Dissertations

Computations have been performed to simulate turbulent supersonic flows past three-dimensional deep cavities with and without yaw. Simulation of these self-sustained oscillatory flows have been generated through time accurate solutions of the Reynolds averaged complete Navier-Stokes equations using two different schemes: (1) MacCormack, finite-difference, (2) implicit, upwind, finite-volume schemes. The second scheme, which is approximately 30% faster, is found to produce better time accurate results. The Reynolds stresses have been modeled, using the Baldwin-Lomax algebraic turbulence model with certain modifications. The computational results include instantaneous and time averaged flow properties everywhere in the computational domain. Time series analyses have been …

Simulation Of Fluid Flow In Packed Beds Using A Simplified Model And Network Analysis Technique, Haggai W.K. Sarakikya

Tanzania Journal of Engineering and Technology (TJET)

Abstract

A Reiner-Rivlin Fluid Flow Through Entrance Region Of A Circular Pipe, V. G. Masanja

Tanzania Journal of Engineering and Technology (TJET)

The flow of a Reiner-Rivlin fluid with two viscosity coefficients through the entrance region of a circular pipe has been studied numerically. In particular the growth of the entrance length as a function of the Reynolds number and the non-Newtonian parameters has been examined. Where comparison could be made, the results have been compared with existing experimental -and numerical data as well as the limited theoretical work available.

Scanning Electron Microscopy And X-Ray Energy Dispersive Spectroscopic Analysis Of Selected Sorbent Materials, Elhamy Amin Sedhom

Theses

A previous study⁽¹⁾ showed that a combination of acidic and basic sorbents in a layered system is required to reduce to safe levels the contaminants present in the leachates emanating from industrial landfills. The sorbents used were fly ash, vermiculite, kaolinite, illite, zeolite, apautagite, bentonite, activated carbon and bauxite.

The purpose of this investigation is to study the physical properties, elemental composition and the distribution of the aforementioned solid sorbents. Properties of interest are particle size, shape and distribution and also the chemical composition and the distribution of the elements within the sample particles.

Scanning Electron Microscopy (SEM) and …

High Temperature Resistant Crosslinked Phenol, O-Chlorophenol And Formaldehyde Copolymer Fiber, Suh Joon Han

Theses

Phenolic copolymer fibers which possess clearly distinguishable physical and chemical properties from other synthetic and natural fibers were prepared. Acid catalyzed condensation polymerization of phenol, formaldehyde and o-chiorophenol was carried out by a two-stage polymerization. Initially, phenol-formaldehyde and o-chlorophenol-formaldehyde oligomers were separately prepared by refluxing the corresponding monomers at 100°C under strong agitation. At the second stage, these two oligomers were combined and vacuum-distilled to form a block copolymer which was then melt spinned into fibers and subsequently cured by succinyl chloride in a mineral spirit. Using a flame test and thermogravimetric analysis, it was found that these cured fibers …

Expert Systems For Automated Maintenance Of A Mars Oxygen Production System, Ming-Tsang Ho

Mechanical & Aerospace Engineering Theses & Dissertations

A prototype expert system has been developed for maintaining autonomous operation of a Mars oxygen production system. Normal operation conditions and failure modes according to certain desired criteria are tested and identified. Several schemes for failure detection and isolation using forward chaining, backward chaining, knowledge-based and rule-based are devised to perform several housekeeping functions. These functions include self-health checkout, an emergency shut down program, fault detection and conventional control activities. An effort has been made to derive the dynamic model of the system using Bond-Graph technique in order to develop the model-based failure detection and isolation scheme by estimation method. …

The Effects Of Nonlinearities On The Optimal Design Of Forced Vibrating Beams, Cheryl Celestine Jackson

Mechanical & Aerospace Engineering Theses & Dissertations

The optimal design of a beam under harmonic excitations is formulated and solved numerically for linear and nonlinear forced vibration theories. The beam has a nonuniform cross-sect ion, whose thickness can change during the optimization procedure. Based on the numerical results, for the given input frequency range, the linear vibration theory produces a more conservative design than the nonlinear vibration theory.

The analytical formulation for both theories is presented. For the linear case, a mean case is defined for the self-weight on a beam, and an alternating case is defined for input forcing frequencies which cause fatigue variations on a …

Molecular Modeling In Anatoxin And Other Semirigid Agonists, Wen-Chung Shang

Theses

Conformational search and molecular mechanics calculations were combined to investigate the structural flexibility of isoquinolone, the anatoxin series, and the ferruginine series. Ring searching allow all rational conformations to be generated.

Isoquinolone shows conformational similarity to isoarecolone but is much less potent which suggests that the proximity of the methyl group beta to the carbonyl groups affects the bioactivity of isoquinolone. The very active agonist-anatoxin, without a similar conformation as isoarecolone, shared a similar electrostatic potential contour in the vicinity between the two atoms connected to the electro-positive nitrogen and hydrogen bonding site. These phenomena were not found in ferruginine …

Determination Of Aromatic Amines By Diazonium Salt, Hong-Hue Hsu

Theses

There are many analytical methods used in the identification of aniline by the production of various colors upon treatment with certain reagents. In this work a new inexpensive, easy and sensitive methods to quantitate aniline is developed. The change of absorbance is large enough to measure with a difference of only 1 ppm in the aniline concentration.

In this method, the reagent (2,4-dinitrodiazonium sulphate) which reacts with aniline produces a yellow color. Formation of this color (which absorbs at 486 nm) indicates the presence of aniline. The amount of aniline can be determined by measuring the absorbance at 486 nm. …

Agitation Requirements For Complete Dispersion Of Emulsions, Dun-Huang Tsai

Theses

An investigation on the minimum agitation speed required to achieve complete dispersion in liquid-liquid systems has been carried out. A model based on the momentum balance for a droplet and on Kolmogoroff's theory of isotropic turbulence was used for the prediction of the role of the most important variables on the minimum agitation speed. The equation so derived can be expressed in terms of a number of non- dimensional groups (such as Re, Ar, and Su). For geometrically similar systems the equation contains only one adjustable parameter ( to be determined experimentally) in the form of the proportionality constant correlating …

The Design, Manufacture And Mechanical Analysis Of An L4-5 Spinal Disc Prosthesis, Bohdan A. Siryi

Theses

The purpose of this research was to develop an intervertebral disc prosthesis which can provide the biomechanical properties of the natural disc. The prosthesis will be used to replace the symptomatic degenerated disc and thereby limit backpain and subsequent spinal disease.

Four cadaveric L4-5 motion segments were mechanically tested under axial compression and combined compression/torsion, generating compressive moduli and torsional stiffness values. Following, prosthetic discs were fabricated and mechanically tested, with the fabrication technique directed towards the optimization of mechanical properties in compression, torsion and bending.

Thirty silicon rubber and forty five polyurethane disc prostheses were fabricated. Silicon rubber, dacron …

The Effect Of Elastic Boundary Conditions On The Dynamic Response Of Rectangular Plates, Terry K. Brewer

Mechanical & Aerospace Engineering Theses & Dissertations

Natural frequencies and forced steady-state harmonic response for the vibration of uniform rectangular plates with edges elastically restrained against rotation and transverse translation are addressed. A single mode Rayleigh-Ritz solution is derived using functions that describe the normal modes of vibration of a beam whose ends are elastically restrained. The finite element solution is obtained for comparison. MACSYMA symbolic manipulation system is implemented as an aid to the mathematical rigor of the Ritz approach and NASTRAN finite element code is used to model the mechanical system. Comparisons are made to published results and the solutions of this study are found …

Large Planar Maneuvers For Articulated Flexible Manipulators, Li-Farn Yang

Mechanical & Aerospace Engineering Theses & Dissertations

An articulated flexible manipulator carried on a translational cart is maneuvered by an active controller to perform certain position control tasks. The nonlinear dynamics of the articulated flexible manipulator are derived and a transformation matrix is formulated to localize the nonlinearities within the inertia matrix. Then a feedback linearization scheme is introduced to linearize the dynamic equations for controller design. Through a pole placement technique, a robust controller design is obtained by properly assigning a set of closed loop desired eigenvalues to meet performance requirements. Numerical simulations for the articulated flexible manipulators are given to demonstrate the feasibility and effectiveness …

An Application Of Global Optimization Algorithm For Modal Parameter Identification, Chung-Men Chen

Mechanical & Aerospace Engineering Theses & Dissertations

Single-mode projection filters for modal parameter identification for flexible structures are introduced. An effective two-dimensional global optimization method using interval analysis is combined with the projection filters to facilitate identification for modal frequency and damping. A numerical simulation of a ten-mode structure is presented to illustrate the feasibility of the new method. The projection filters are practical for parallel processing implementation.

Development Of Load Carrying Thermoplastic Components For An Automotive Emergency Braking System, Joseph Gerard Sikora

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis describes a classical approach to plastic parts' design leading to the development of load carrying fiber reinforced thermoplastic components for use in an automotive emergency braking system. The control arms that are the focus of this study are designed to withstand the static loads characteristic of the loads experienced by an automotive emergency braking system. The present study is particularly significant as a case study because the design involves development of load carrying components for use in the harsh automotive environment.

Beginning with a fundamental concept for the control arms, basic design criteria, and a limited insight into …

Analysis And Design Sensitivity Computations Of Nonlinear Free And Forced Vibrations Of Stepped Beams, Yong Xiang Xue

Mechanical & Aerospace Engineering Theses & Dissertations

A finite element method is developed in this thesis for analyzing stepped beams under nonlinear free and forced vibrations. A new assumption is made to improve an existing finite element procedure for treating beams of nonuniform cross sections. The geometric nonlinearity results from the nonlinear, strain-displacement relation due to large deflection of a beam.

Based on an improved finite element procedure a computational method is then established for design sensitivity analyses of nonlinear eigenproblems pertaining to the free and forced nonlinear vibrations of beams. It is found that the equation for computing the design sensitivity of eigenvector is linear and …

Analysis And Optimal Design Of Pyramidal Truss Core Panels, Mark A. Wiseman

Mechanical & Aerospace Engineering Theses & Dissertations

The Pyramidal Truss Core Panel has been developed to save weight in applications normally devoted to solid plates. Present design formulas use classical beam theory with engineering assumptions made for moment of inertia and shear modulus determinations. Analysis with the SUPERSAP finite element code indicates that the present theory provides good prediction for the plate stresses but may be inadequate for the core stress and deflection determination. Two optimization routines are presented. The first procedure uses a batch file to execute separate programs with SUPERSAP used as the analysis code. The second combines a FORTRAN program used for analysis with …

Approaches To The Synthesis Of Dentin Bonding Agents Containing Vinyl And Carbamate Functional Groups, Steven W. Amato

Theses

The synthesis of four new monomers containing vinyl and carbamate functional groups was attempted. The desired products were N-m-methacryloxyphenyl-O-phenyl carbamate, N-p-methacryloxy-O-phenyl carbamate, m-N-phenylcarbamato-2-methacryloxyethoxy benzoate, and p-N-phenylcarbamato-2-methacryloxyethoxy benzoate. The carbamate functional group was derived by the Lewis Acid catalyzed reaction of meta-aminophenol, para-aminophenol, meta-aminobenzoic acid, and para-aminobenzoic acid with diphenyl carbonate. The vinyl function was derived, in the case of the aminophenols, by reaction with methacrylyl chloride, and in the case of the aminobenzoic acids, with 2-hydroxyethyl methacrylate.

Partial products only were prepared, these being the two carbamate functional phenols, the two carbamate functional benzoic acids, the two methacryloxy functional derivatives …

Geometric And Enthalpic Calculational Study Of Monosubstituted Cyclobutanes ; Attempted Synthesis Of 1,3-Diphenyl-2,2,4,4-Tetrafluorobicyclo [1.1.0] Butane, Jose Luis Reyesgavilan

Theses

The work undertaken in this thesis is in two parts. In the first, the structure and heat of formation of substituted cyclobutanes were studied via the computer program MMII using an IBM PCXT personal computer with a math co-processor chip. Structurally, a trend was seen to be followed in which bulkier substituents were pushed away from any steric interaction with the ring. This was accomplished by having the latter alter its puckering angle, C2C1C4 angle, HCX angle, and to a smaller extent, the bond lengths immediately adjacent to the substituted carbon atom. This results demonstrated that the ring was very …

Experimental Parametric Study Of A True Airspeed Sensor, Adel R. Ibrahim

Mechanical & Aerospace Engineering Theses & Dissertations

The results of an experimental parametric study of a true airspeed sensor are presented. The objective of this study was primarily to investigate experimentally the parameters that effect the frequency response of the true airspeed sensor. A secondary objective was to identify the sensor configuration which achieved the best performance. The model used to conduct these experiments basically consisted of swirl generator and vortex tube sections and pick-up signal system. A regression analysis was performed on the experimental results to obtain the effect of each parameter individually on the frequency response. The most significant parameters were selected by the regression …

Coupled Bending-Torsion Steady-State Response Of Pretwisted, Nonuniform Rotating Beams Using A Transfer-Matrix Method, Carl E. Gray Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Using the Newtonian method, the equations of motion are developed for the coupled bending-torsion steady-state response of beams rotating at constant angular velocity in a fixed plane. The resulting equations are valid to first order strain-displacement relationships for a long beam with all other nonlinear terms retained. In addition, the equations are valid for beams with the mass centroidal axis offset (eccentric) from the elastic axis, nonuniform mass and section properties, and variable twist. The solution of these coupled, nonlinear, nonhomogeneous, differential equations is obtained by modifying a Hunter linear second-order transfer-matrix solution procedure to solve the nonlinear differential equations …