Mechanical Engineering Commons^™

A Numerical Study Of Curved Labyrinth Seals For Steam Turbines, Sricharan Kishore Ayyalasomayajula

Masters Theses

A numerical experiment has been conducted to study and evaluate the structural behavior of newly designed labyrinth seals. Structural analysis was performed to understand, evaluate and compare new seals with a baseline straight seal that is typical of commonly used seals in steam turbines. New configurations of labyrinth seal knives were developed for use in steam turbines [17]. The main objective of this study is to develop a better understanding of selected various labyrinth seals that may be configured to minimize the steam leakage and reduce seal interactions with the shaft. Computational fluid dynamic modeling of the various configurations, from …

Topology Optimization Of Carbon Nanotube Reinforced Polymer Damping Structures, Seshadri Mohan Varma Damu

Masters Theses

Topology optimization has been successfully used for improving vibration damping in constrained layer damping structures. Reinforcing carbon nanotubes in a polymer matrix greatly influence the mechanical properties of the polymer. Such nanotube-reinforced polymers (NRP) can be used to further enhance the damping properties of the constrained layer structures. In this work, topology optimization is performed on constrained damping layer structures using NRP in order to maximize the loss factor for the first resonance frequency of the base beam. In addition to the material fractions of the NRP and elastic material, the volume fraction of the nanotubes in the polymer is …

A Cartesian Space Approach To Teleoperate A Slave Robot With A Kinematically Dissimilar Redundant Manipulator, Hariharan Ananthanarayanan

Masters Theses

Due to the inability of humans to interact with certain unstructured environments,
telemanipulation of robots have gained immense importance. One of the primary tasks in telemanipulating robots remotely, is the effective manipulation of the slave robot using the master manipulator. Ideally a kinematic replica of the slave manipulator is used as the master to provide a joint-to-joint control to the slave. This research uses the 7-DOF Whole Arm Manipulator© (WAM) as the master manipulator and a 6-DOF Titan as the slave manipulator. Due to the kinematic dissimilarity between the two, a Cartesian space position mapping technique is adapted in which …

Reverse-Flow Oxidation Catalyst With Supplemental Fuel Injection For Lean-Burn Natural Gas Engines, Steven Scott Smith

Masters Theses

The purpose of this research is to demonstrate that the use of a reverse-flow oxidation catalyst reactor (RFOCR), both with and without supplemental fuel injection (SFI), will result in significant reductions of methane (CH4) in a simulated lean-burn natural gas exhaust mixture. Methane reduction is investigated as a function of the directional duration of the exhaust gases through the oxidation catalyst, gas hourly space velocity (GHSV), and exhaust gas temperature. The CH4 catalytic chemical reaction, at an elevated exhaust gas temperature, is an exothermic reaction and elevating the temperature across the catalyst reactor corresponds to an increase in CH4 conversion. …

Clinical Significance Of Hip Separation In Metal On Polyethylene, Metal On Metal, And Ceramic On Ceramic Tha Due To Resonant And Energy Dispersion Effects, Joseph Scott Bader

Masters Theses

Femoral head sliding within the acetabular cup does occur in THA. Since it is
known that impact conditions can lead to component ringing, the present study
investigates the vibrational response of variable bearing surface materials. A further understanding of the physical response resulting from impact during femoral head sliding may lead to valuable insight pertaining to THA failure.
Accelerometers were mounted to synthetic bones which had been implanted with hip prostheses. Data was collected from these sensors as a machine impacted the femoral head into the acetabular cup. These tests were carried out for metal-metal, ceramicceramic, and metal-polyethylene bearing surfaces …

Mechanical Design And Integration Of A Tracking Fluoroscope System, Robert Bradley Cunningham

Masters Theses

The Tracking Fluoroscope System (TFS) – patent pending serial number 60/606,480 – is a robotic platform designed to follow a patient's natural, uninhibited walking motion and obtain full-range-of-motion x-ray videos of a patient's ankle, knee, or hip. The video data can be used to analyze dynamics within the human body and develop mathematical models of the joints. The TFS can also be used to study artificial implants under various conditions in order to design more effective versions. Similar systems could be used to aid surgeons in artificial implant procedures. Athletic motions could be analyzed to design more effective sports equipment …

Novel Approaches In The Thermal Management Of Electronics Involving Coupled Electrical, Thermal And Cfd Analysis, Bahram Zandi

Doctoral Dissertations

The cooling of electronic components is one of the most important tasks in the design packaging of electronic equipments as insufficient thermal control can lead to low reliability, short life, and failure of the electronic components. According to a study conducted by Philips Corporation, every ten degree Celsius increase in temperature causes a fifty percent decrease in the operating life of many integrated circuits.

With the increasing design complexities and reliability requirements, today’s electronic design engineers rely significantly on software packages (often based on methods of Computational Fluid Dynamics, or CFD) for the prediction of electronics operational temperature. In the …

Adaptive Control Of Axisymmetric Jets By Cavities, Abraham Joseph Meganathan

Doctoral Dissertations

Actuators capable of producing large amplitude oscillations at desired frequencies are needed in many flow control applications. In this dissertation, turbulent jets were actuated using self-sustaining oscillations in axisymmetric cavities. Tested geometries include baseline turbulent jets passing through axisymmetric cavities, with and without peripheral walls. Cavity length to depth ratio (Lc/Dc) was varied from 1 to 5 and data were collected at several intermediate steps. Tests were performed with air over a Reynolds number, based on jet exit diameter, range of 40,000 to 225,000 in low to high subsonic jet flow conditions. Pressure signals, 2D velocity data obtained using Particle …

Modeling And Simulation Of A Trailer With Band Track Over Wheels, Hemmant Gopal

Masters Theses

No abstract provided.

Analytical And Experimental Modal Analysis Of A Micro Cantilever Beam, Aaron Lee Echols

Masters Theses

Micro cantilever beams are used extensively in experimental nanomechanics. They were initially used as an integral component in atomic force microscopes (AFM) to map surfaces or objects with micro, nano, or even atomic precision. Recently, micro cantilever sensors are being studied for possible use in determining bio/chemical agents under a variety of military and homeland security conditions. The key here is to identify the absorbed agent in terms of cantilever deflections, whether static or dynamic. Micro cantilevers are also being studied for possible use in micro/nano engines. In this case, micro particles impact micro cantilevers as a result of Brownian …

Motion Control For A Tracking Fluoroscope System, Gabriel Rinaldo Preliasco

Masters Theses

The tracking fluoroscope system (TFS), patent pending serial No.: 60/606,480; is a vehicle carrying a fluoroscope to take x-rays movies of person’s joints. Fluoroscope, composed by a radiation source and image intensifier, is moved by a total of four servomotors following a subject’s joint. At the same time, vehicle has to follow the subject using two driving-steering servomotor wheels. This thesis is the result of internal research developed at the Mechanical Aerospace Biomedical Engineering Department at the University of Tennessee.

The thesis objective is to determine the best control system for TFS subject tracking function in linear translational mode. Kinematic …

Investigation Of The Kinetics Of No Reduction By Ammonia On An Automotive Catalyst, Trevor Winoker Miller

Masters Theses

As lean-burn engines are being introduced in the United States, both advantages and disadvantages arise. Lean-burn engines can operate at a high efficiency, and are developed for a wide range of power supplies. Unfortunately, due to the low temperature at which these engines operate, NO_x formation becomes an issue. Forthcoming legislation pertaining to heavy-duty lean-burn engines aimed at reducing both particulate matter emissions and emissions of nitric oxides has brought about a need for a better method for reducing NO_x from lean exhaust gases at moderate temperatures. It is generally accepted that current fuel treatment processes alone will …

Fracture Toughness: Evaluation Of Testing Procedure To Simplify Jic Calculations, Brandon Paul Pehrson

Masters Theses

The purpose of this study is to examine the current fracture toughness test procedure and to determine if there is an easier, less complicated method to get the J_Ic value from a test record for fracture toughness specimens. The current method for constructing J_Ic is complicated and involves a detailed computer program or spreadsheet. The objective in this study is to simplify the analysis for the determination of J_Q.

This study has shown that the load and displacement record for a fracture toughness specimen can be used to directly estimate a J_Q value, a provisional …

Power Spectral Density (Psd) Terrain Modeling For Vehicle Durability Analysis, Ezhilventhan Sivanesan

Masters Theses

With the advancement in computer technology, computer simulations of dynamic systems have progressed a lot. During dynamic simulation of automotive systems, terrain profile plays a significant role in determining the ride comfort and the fatigue durability of the systems. The usage of actual test course elevation data might be voluminous and might slow down the simulation speeds. The purpose of this thesis is to study the possibility of re-creating the terrain profiles from the Power Spectral Density of the original terrain profiles so that less voluminous terrain profile data can be used to accelerate the vehicle simulations using dynamic modeling …