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Theses/Dissertations

1995

Mechanical Engineering

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Full-Text Articles in Engineering

Investigation Of Dynamic Friction In Lubricated Surfaces, Hanuman Rachoor Dec 1995

Investigation Of Dynamic Friction In Lubricated Surfaces, Hanuman Rachoor

Dissertations

The research reported in this dissertation is concerned with the development of friction models for lubricated contacts. A few analytical models have been developed to investigate the friction under dynamic velocity conditions. In this study, two different tribological situations such as conformal and non-conformal contacts have been chosen. Friction modeling covers boundary, mixed and full fluid film friction regions. A new theory based on the elastic properties of the surface materials, and fluid film properties of the lubricant at the contact has been developed to determine the dynamic friction in boundary, mixed and full hydrodynamic lubrication regions. In the full ...


Design And Analysis Of Environmentally Safe Cooling Systems For Machine Tools, Haiping Xu Dec 1995

Design And Analysis Of Environmentally Safe Cooling Systems For Machine Tools, Haiping Xu

Theses

Many cooling systems of metal cutting and both their advantages and disadvantages have been reviewed. The cutting forces' relationships, stress distribution, energy consumption and heat generation of orthogonal processes are discussed. A two-dimensional finite element model has been developed to design and analyze a new proposed cooling device, which comes from the idea of "A Novel Cooling Device" proposed by Billatos et al. First, a thermal calculation is completed to compare the temperature difference between two different shapes of coiled pipe. Then, three different cutting conditions, which were considered in the experiments by Childs et al, are conducted under three ...


Real Time Control Of Nonlinear Dynamic Systems Using Neuro-Fuzzy Controllers, Amitava Jana Dec 1995

Real Time Control Of Nonlinear Dynamic Systems Using Neuro-Fuzzy Controllers, Amitava Jana

Dissertations

The problem of real time control of a nonlinear dynamic system using intelligent control techniques is considered. The current trend is to incorporate neural networks and fuzzy logic into adaptive control strategies. The focus of this work is to investigate the current neuro-fuzzy approaches from literature and adapt them for a specific application. In order to achieve this objective, an experimental nonlinear dynamic system is considered. The motivation for this comes from the desire to solve practical problems and to create a test-bed which can be used to test various control strategies. The nonlinear dynamic system considered here is an ...


Design For Quality Manufacturability Analysis Of Total Nonconformity Damaged Parts, Samir R. Gami Dec 1995

Design For Quality Manufacturability Analysis Of Total Nonconformity Damaged Parts, Samir R. Gami

Theses

The competitive nature of modern manufacturing, demands that innovative approaches be applied in order to have a competitive edge. Shortening the product development cycle, the period from initial design to full production, is a priority for most manufacturers today. The DFQM methodology addresses the issue of quality manufacturability (QM) - the likelihood that defects will occur during manufacture of a product in a standard plant. As a consequence, DFQM helps to shorten the design cycle time. The DFQM architecture identifies a variety of design factors and variables that influence specific defects. This process of influencing defects can be described by error ...


Implementation Of A Three-Dimensional Non-Intrusive Particle Tracking System, Vivek Gupta Dec 1995

Implementation Of A Three-Dimensional Non-Intrusive Particle Tracking System, Vivek Gupta

Theses

A Three-Dimensional Non-Intrusive Particle Tracking System has been developed at NJIT's Particle Technology Center to provide experimental results for validating theories being developed in the field of Particle Technology. The system utilizes the principle of magnetic induction between several high-frequency miniature transmitters mounted inside a sphere and a set of receiving loop antennae mounted outside the experimental apparatus. Basic theories and algorithms for the tracking system have already been developed. The focus of this thesis is to make the tracking system more accurate, reliable and user-friendly and to apply it to the study of vibrated beds and chute flows ...


An Investigation Of Turbulent Taylor-Couette Flow Using Laser Doppler Velocimetry In A Refractive Index Matched Facility, Joseph C. Parker Dec 1995

An Investigation Of Turbulent Taylor-Couette Flow Using Laser Doppler Velocimetry In A Refractive Index Matched Facility, Joseph C. Parker

Master's Theses

Turbulent Taylor-Couette flow between an annulus formed by two concentric cylinders with dead end walls is comprised of complex patterns of vortices. An experimental apparatus was designed to provide refractive index matching between the annulus and working fluid. Optical access was maintained through three sides of the annulus and one end wall. An aqueous solution of sodium iodide was formulated to match the refractive index of the Plexiglas annulus. Laser Doppler Velocimetry was used to measure the three components of velocity and turbulence intensity throughout a planar section in the annulus. The annulus dimensions were: ƞ= 0.672, d = 15 ...


The Effect Of Rotor Wake/Exit Guide Vane Interaction On The Total Pressure Losses In An Airfoil Cascade, Aaron Mosebach Dec 1995

The Effect Of Rotor Wake/Exit Guide Vane Interaction On The Total Pressure Losses In An Airfoil Cascade, Aaron Mosebach

Master's Theses

Computational simulations have been performed to study the effects of unsteady rotor wakes on the total pressure losses and the boundary layer characteristics in a compressor cascade. In the numerical simulations, transitional and turbulent flow conditions were modeled at design and off-design inlet flow angles, and for varying rotor wake widths and wake velocity deficits.

First, simulations were performed in the absence of rotor wakes at the inlet of the EGV (Exit Guide Vane) cascade. Second, simulations were performed for different wake width and wake velocity deficit values at the inlet of the EGV cascade. The majority of the numerical ...


Dynamic Pulse Buckling Of Columns With Viscous Damping, Murli Kadandale Dec 1995

Dynamic Pulse Buckling Of Columns With Viscous Damping, Murli Kadandale

Master's Theses

This is a study of dynamic pulse buckling of columns with viscous damping. The differential equations of motion were obtained using the Bemoulli-Navier hypothesis. The effects of axial and rotary inertia were included in the analysis. The Voigt-Kelvin model for a viscoelastic material is used. The Finite Difference Method was employed to solve the differential equations of motion. First columns without geometrical imperfections were studied, and a correlation between the damping modulus and the more familiar damping ratio was obtained. Then beams with initial geometrical imperfection were studied. A suitable dynamic buckling criterion was defined. It was observed that viscous ...


Malt Drying Model Verification For Efficiency Improvement, John David Kribs Nov 1995

Malt Drying Model Verification For Efficiency Improvement, John David Kribs

Dissertations and Theses

The aim of this work has been to minimize the thermal energy required to dry malt in deep beds while maintaining malt quality, and without increasing the drying time more than one hour. Malt drying usually takes place in deep bed (. 7-1 m) driers by forcing hot air through the bed. Measurements of inlet and outlet relative humidity, temperature, and airflow at a drier at Great Western Malting Company's Vancouver, Washington facility were made to find average moisture content versus time. The measurements were used to develop a wetted surface model of a malt bed. However, the model was ...


Vibration As An Aid In Robotic Peg-In-Hole Assembly, Hsin-Te Liao Oct 1995

Vibration As An Aid In Robotic Peg-In-Hole Assembly, Hsin-Te Liao

Dissertations

This dissertation presents an analytical and experimental investigation of vibration assisted engagement for parts mating. A dynamic model of assembly is established by using Lagrange's equation for impact to derive impact equations for a robotic manipulator in peg-in-hole assembly. The model can be used to analyze part motion and contact force in the mating of parts by robots. The impact equations of a SCARA robot are derived using this model and utilized to investigate how robot configuration, insertion speed, chamfer angle, coefficient of restitution and other system parameters affect impulsive force and departure angle in the assembly of a ...


Particle Deposition On Surfaces In A Divergent Channal Flow, Ding Sun Oct 1995

Particle Deposition On Surfaces In A Divergent Channal Flow, Ding Sun

Dissertations

Particle trajectory and deposition of two phase gas-solid flows in a convergent or divergent two-dimensional channel are investigated numerically in a wide range of parameters. For the fluid phase, a two dimensional, incompressible laminar fluid flow is considered in the analysis. The particle phase is a diluted suspension. The effects of inertia, gravity, viscous force and electrostatic image force are included in the computational model.

Both convergent and divergent channel flow are solved by the finite element method based on the software FIDAP. The flow separations will appear in a divergent channel and their separation positions are obtained in the ...


Chute Flow Experiments, Yahong Zhang Oct 1995

Chute Flow Experiments, Yahong Zhang

Theses

The objective of this thesis is to study the behavior of granular materials flowing down an inclined chute using three diagnostic techniques under different chute inclination angles and chute floor conditions. The three methods are: (1) tracking the motion of single particle within the mass in a noninvasive manner using a transmitting sphere and antenna receiving system, (2) scale mass flow rate measurement, and (3) high speed camera system to obtain flow velocity measurements.

For these purposes, an experimental setup has been completed and a set experiments has been performed.


The Effect Of Liquid Gallium On Plastics, Vivek P. Dwivedi Oct 1995

The Effect Of Liquid Gallium On Plastics, Vivek P. Dwivedi

Theses

As part of a joint effort by Cornell University and NJIT to find a replacement for mercury as a pressuring medium for P-V-T devices, we investigated the effect of liquid gallium on four thermoplastics: two semi-crystalline ( high density polyethylene and polypropylene ) and two amorphous ( polystyrene and polymethylmethacrylate ). Test specimens were covered with liquid gallium and held in vacuum oven at temperatures close to their melting points for up to two weeks. Change in weight after treatment with gallium was measured, along with tensile testing and particle analysis using dispersion x-ray spectroscopy. The results are compared with specimens treated under identical ...


Auditing & Measuring The Need For Flexibility In A Manufacturing Facility, Kartika-Sari Stroman Oct 1995

Auditing & Measuring The Need For Flexibility In A Manufacturing Facility, Kartika-Sari Stroman

Theses

Flexible manufacturing was created out of the need for facilities to be able to efficiently respond to changes in their environment so as to build a competitive advantage. Flexible manufacturing (FM) is currently viewed as a way for facilities to be able to introduce and produce multiple products quickly and more efficiently. In this research we will present some new tools to help managers address the changes that are affecting the facility.

An audit was developed to help system designers identify the changes that are impacting the facilities. The audit provides the opportunity to understand the changes that are occurring ...


Buckling Analysis And Optimum Design Of Multidirectionally Stiffened Composite Curved Panel, Navin R. R. Jaunky Oct 1995

Buckling Analysis And Optimum Design Of Multidirectionally Stiffened Composite Curved Panel, Navin R. R. Jaunky

Mechanical & Aerospace Engineering Theses & Dissertations

Continuous filament grid-stiffened structure is a stiffening concept that combines structural efficiency and damage tolerance. However, buckle resistant design optimization of such structures using a finite element method is expensive and time consuming due to the number of design parameters that can be varied. An analytical optimization procedure which is simple, efficient and supports the preliminary design of grid-stiffened structures for application to combined loading cases is needed.

An analytical model for a general grid-stiffened curved panel is developed using an improved smeared theory with a first-order, shear-deformation theory to account for transverse shear flexibilities and local skin-stiffener interaction effects ...


An Experimental Investigation Of Wall Cooling Effects On Hypersonic Boundary Layer Stability In A Quiet Wind Tunnel, Alan E. Blanchard Oct 1995

An Experimental Investigation Of Wall Cooling Effects On Hypersonic Boundary Layer Stability In A Quiet Wind Tunnel, Alan E. Blanchard

Mechanical & Aerospace Engineering Theses & Dissertations

One of the primary reasons for developing quiet tunnels is for the investigation of high-speed boundary-layer stability and transition phenomena without the transition-promoting effects of acoustic radiation from tunnel walls. In this experiment, a flared-cone model under adiabatic- and cooled-wall conditions was placed in a calibrated, 'quiet' Mach 6 flow and the stability of the boundary layer was investigated using a prototype constant-voltage anemometer. The results were compared with linear-stability theory predictions and good agreement was found in the prediction of second-mode frequencies and growth. In addition, the same 'N=10' criterion used to predict boundary-layer transition in subsonic, transonic ...


Atec: The Aerodyanmic Turbine Engine Code For The Analysis Of Transient And Dynamic Gas Turbine Engine System Operations, Glenn Douglas Garrard Aug 1995

Atec: The Aerodyanmic Turbine Engine Code For The Analysis Of Transient And Dynamic Gas Turbine Engine System Operations, Glenn Douglas Garrard

Doctoral Dissertations

A new one-dimensional, time dependent aerothermodynamic mathematical model and computer simulation of the gas turbine engine has been developed and is introduced herein. The Aerodynamic Turbine Engine Code (ATEC) simulates the operation of the gas turbine engine by solving conservation equations, expressed as one dimensional, time dependent Euler equations, with turbomachinery source terms. By incorporating both implicit and explicit equation solvers, transient simulations of the gas turbine engine can be conducted efficiently while maintaining the capability of simulating dynamic events such as compressor stall. ATEC can also be used to address dynamic events or steady-state processes to model both on- ...


A Theoretical Nonlinear Dynamical Model Of Coupled Heat And Momentum Transfer In Forced Convection Film Boiling, Jolie Ann Long Aug 1995

A Theoretical Nonlinear Dynamical Model Of Coupled Heat And Momentum Transfer In Forced Convection Film Boiling, Jolie Ann Long

All Theses

In film boiling, a layer of vapor completely blankets the heated surface and prevents liquid contact with the surface. Film boiling is usually considered undesirable because it is an inefficient mode of heat transfer and can lead to temperatures in excess of those allowed for many materials. Because film boiling may inhibit desired heat transfer in several processes including metals manufacturing, cryogenic engineering, and electronic cooling, it is useful to consider how the film boiling vapor layer may be destabilized or altered such that time-averaged heat transfer is improved.


Nonlinear Transient Thermal Analysis By The Force-Derivative Method, Narayani V. Balakrishnan Jul 1995

Nonlinear Transient Thermal Analysis By The Force-Derivative Method, Narayani V. Balakrishnan

Mechanical & Aerospace Engineering Theses & Dissertations

The force-derivative method (FDM) represents a series of higher-order modal methods which offer an increasingly improved approximation of the higher modes neglected in the basic mode-displacement method (MDM). The FDM includes additional terms which involve the forcing function and derivatives of the forcing function with respect to time. The mode-acceleration method (MAM), extensively used in structural analysis, is a first-order form of the FDM which includes only one correction term that depends on the forcing function itself. The success of the FDM in many structural dynamic applications has prompted its application for solving transient thermal problems. The superior convergence of ...


Numerical Investigation Of Shock-Induced Combustion Past Blunt Projectiles, Jagjit K. Ahuja Jul 1995

Numerical Investigation Of Shock-Induced Combustion Past Blunt Projectiles, Jagjit K. Ahuja

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical study is conducted to simulate shock-induced combustion in premixed hydrogen-air mixtures at various free-stream conditions and parameters. Two-dimensional axisymmetric, reacting viscous flow over blunt projectiles is computed to study shock-induced combustion at Mach 5.11 and Mach 6.46 in hydrogen-air mixture. A seven-species, seven reactions finite rate hydrogen-air chemical reaction mechanism is used combined with a finite-difference, shock-fitting method to solve the complete set of Navier-Stokes and species conservation equations. In this approach, the bow shock represents a boundary of the computational domain and is treated as a discontinuity across which Rankine-Hugoniot conditions are applied. All interior ...


Dynamic Unstructured Method For Prescribed And Aerodynamically Determined Relative Moving Boundary Problems, Kamakhya Prasad Singh Jul 1995

Dynamic Unstructured Method For Prescribed And Aerodynamically Determined Relative Moving Boundary Problems, Kamakhya Prasad Singh

Mechanical & Aerospace Engineering Theses & Dissertations

A new methodology is developed to simulate unsteady flows about prescribed and aerodynamically determined moving boundary problems. The method couples the fluid dynamics and rigid-body dynamics equations to capture the time-dependent interference between stationary and moving boundaries. The unsteady, compressible, inviscid (Euler) equations are solved on dynamic, unstructured grids by an explicit, finite-volume, upwind method. For efficiency, the grid adaptation is performed within a window around the moving object. The Eulerian equations of the rigid-body dynamics are solved by a Runge-Kutta method in a non-inertial frame of reference. The two-dimensional flow solver is validated by computing the flow past a ...


Studies Of Mixing Processes In Gases And Effects On Combustion And Stability, Frank Paul Kozusko Jr. Jul 1995

Studies Of Mixing Processes In Gases And Effects On Combustion And Stability, Frank Paul Kozusko Jr.

Mathematics & Statistics Theses & Dissertations

Three physical models of laminar mixing of initially separated gases are studied. Two models study the effects of the mixing dynamics on the chemical reactions between the gases. The third model studies the structure and stability of a laminar mixing layer in a binary gas. The three models are:

1. Two ideal and incompressible gases representing fuel and oxidizer are initially at rest and separated across an infinite linear interface in a two dimensional system. Combustion, expected as the gases mix, will lead to a rapid rise in temperature in a localized area, i.e. ignition. The mixing of the ...


A Comparative Study Of The Stress Concentration Factors Arising Between Two Equal, Nearly Intersecting, Perpendicular, Pressurized Holes In An Infinite Solid With Those Arising Due To An Infinite Series Of Such Holes, Paul J. Drogowski Jun 1995

A Comparative Study Of The Stress Concentration Factors Arising Between Two Equal, Nearly Intersecting, Perpendicular, Pressurized Holes In An Infinite Solid With Those Arising Due To An Infinite Series Of Such Holes, Paul J. Drogowski

Master's Theses

Finite element analysis is used to determine the stress concentration factors arising from two equal, perpendicular, nearly intersecting, pressurized holes in an infinite solid while varying the distance and pressure ratios between the holes. The results are compared and contrasted with those previously obtained for an infinite series of such holes. A ratio of the distance between the holes to the diameter of the holes at which the holes can be considered to be single holes in an infinite solid is determined. A study is performed to determine a correlation between the location of the region of maximum stress and ...


Advanced Rover Chassis, Eric Alan Poulson, Collin Lewis, Todd Graves May 1995

Advanced Rover Chassis, Eric Alan Poulson, Collin Lewis, Todd Graves

Undergraduate Honors Capstone Projects

Background:

The six wheeled rover vehicle detailed in this design is intended as an upgrade test bed for the sensor array and autonomous navigation algorithms in use by Utah State University's Center for Self-Organizing and Intelligent Systems (CSOIS). The CSOIS's sensor suite can successfully detect and avoid unnavigable obstacles up to five vehicle lengths in front of the vehicle. The center presently uses a modified RC type chassis and only supports two wheel drive. This chassis was adequate to bring the CSOIS's algorithms to a proof-of-principles state, but in order to place the system in any practical ...


Closed-Loop Identification Of Unstable Systems In Time And Frequency Domains, Hyun Chang Lee Apr 1995

Closed-Loop Identification Of Unstable Systems In Time And Frequency Domains, Hyun Chang Lee

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation presents closed-loop identification algorithms of an unstable system in the time and frequency domains. In the time domain, the projection filter, which is a linear transformation which projects (transforms) a finite number of input-output data of a system into its current space, is used to relate the state-space model with a finite difference model. The method developed can take into account the effects of process noise as well as measurement noise and identify open-loop systems with unknown feedback dynamics in the closed-loop operation. Then the recursive relations between Markov parameters and the ARX model are derived to identify ...


Finite Element Nonlinear Random Response Of Composite Panels Of Arbitrary Shape To Acoustic And Thermal Loads Applied Simultaneously, Roger R. Chen Apr 1995

Finite Element Nonlinear Random Response Of Composite Panels Of Arbitrary Shape To Acoustic And Thermal Loads Applied Simultaneously, Roger R. Chen

Mechanical & Aerospace Engineering Theses & Dissertations

The nonlinear random response of composite plates to the simultaneously applied, combined acoustic/thermal loads are investigated in this dissertation. A finite element formulation for the nonlinear random response is developed. The three-node Mindlin plate element with improved transverse shear is extended and employed. The extension includes the development of the thermal geometric matrix, the mass matrix, the first- order and second-order nonlinear stiffness matrices, and the thermal and mechanical load vectors. An innovative solution procedure has been created which is believed to be the first attempt to analyze nonlinear random response of complex composite panels subjected to simultaneous acoustic ...


Aerodynamic Design Optimization With Consistently Discrete Sensitivity Derivatives Via The Incremental Iterative Method, Vamshi M. Korivi Apr 1995

Aerodynamic Design Optimization With Consistently Discrete Sensitivity Derivatives Via The Incremental Iterative Method, Vamshi M. Korivi

Mechanical & Aerospace Engineering Theses & Dissertations

In this study which involves advanced fluid-flow codes, an incremental iterative formulation (also known as the "delta" or "correction" form), together with the well-known spatially split approximate-factorization algorithm, is presented for solving the large, sparse systems of linear equations that are associated with aerodynamic sensitivity analysis. For the smaller two dimensional problems, a direct method can be applied to solve these linear equations in either the standard or the incremental form, in which case the two are equivalent. However, iterative methods are needed for larger two-dimensional and three dimensional applications because direct methods require more computer memory than is currently ...


Component Mode Synthesis-Based Design Methodology For Structural Modification And Synthesis, Venkateshwarlu Maroju Apr 1995

Component Mode Synthesis-Based Design Methodology For Structural Modification And Synthesis, Venkateshwarlu Maroju

Mechanical & Aerospace Engineering Theses & Dissertations

In this work, structural modification and synthesis techniques based on component mode synthesis are presented. The component mode synthesis method formulates the eigenvalue equation of an entire structure in terms of the vibration characteristics of individual components in the assembly. Through this functional relationship, the individual components are successfully treated as the design entities in the proposed methodology. Unlike conventional design modification techniques that can only treat the properties of the finite elements as the design variables, this technique uses the vibration and static responses of the individual components as the design entities. The sensitivity derivatives of the global responses ...


Minimizing The Radiated Sound Power With Minimal Structural Modification , Daniel Henry Kruger Jan 1995

Minimizing The Radiated Sound Power With Minimal Structural Modification , Daniel Henry Kruger

Retrospective Theses and Dissertations

In cases where a structure's excitation cannot be altered, the sound radiation from the structure must be minimized by modifying the structure within given design constraints. This dissertation considers minimizing sound radiated by an existing structure with minimal changes to the structure itself. To accomplish this the sound power radiated by a structure was written as a function of the normal surface velocity using the boundary element method. The feasibility of reducing radiated sound power with small patches of constrained layer damping material is proved. Small patches of constrained layer damping material are placed on the structure to effectively ...


Development Of An Acoustic Microscope To Measure Residual Stress Via Ultrasonic Rayleigh Wave Velocity Measurements , Jane Carol Johnson Jan 1995

Development Of An Acoustic Microscope To Measure Residual Stress Via Ultrasonic Rayleigh Wave Velocity Measurements , Jane Carol Johnson

Retrospective Theses and Dissertations

High stress in a crucial instrument part can cause failure. Stress detection is one of the aims of nondestructive testing. The velocity change of acoustic waves can be used to detect stress in a material. An acoustic microscope is an instrument which induces and detects acoustic waves and in one mode of operation, is able to measure the velocity of acoustic surface waves. It does this over a very small area and is capable of high spatial resolution;One of the challenges in the measurement of stress is the achievement of high spatial resolution. Since the stress induced velocity shifts ...