Mechanical Engineering Commons^™

A K-Epsilon Extension For Wall-Bounded Flows On The Broadband Aeroacoustic System Simulator, David González

Masters Theses

The turbulence modeling capabilities of the Broadband Aeroacoustic System Simulator (BASS), an experimental code developed at NASA Glenn Research Center, have been extended to include wall-bounded flow capabilities. This was done by first validating the code's viscous solving routines by comparing numerical solutions to known, simple analytic solutions. Finally, the dynamics of the wall shear flows were accounted for with the use of wall-damping functions incorporated into the turbulence model. The results for both viscous and turbulence routines agree well with published data.

Mixing Flow Structures Of Scalloped, Forced Lobed Mixers Using Piv And Plif Measuring Techniques, Nathan J. Cooper

Masters Theses

An Experimental study of internal forced lobed mixers similar to those used in jet aircraft engines is performed using whole field species concentration and velocity measuring techniques. Planar temperature and velocity measurements using Planar Laser Induced Fluorescence (PLIF) and 2D Particle Image Velocimetry (PIV) are performed for lobed, lobed scalloped and splitter mixers in aqueous solution. Specific emphasis is given to study scallops or notches cut into the mixer trailing edge and their role in mixing enhancement. Mixing is compared through velocity and species concentration measurements on axial and streamwise planes for the three dimensional, forced mixers in a confined …

Ductile Regime Nano-Machining Of Silicon Carbide, Biswarup Bhattacharya

Masters Theses

This thesis describes experimental work carried out to study the ability to ductile . single point diamond turn both polycrystal Silicon Carbide (SiC) and chemically vapor deposited (CVD) SiC. A Precitech diamond turning machine was used for ductile regime machining of polycrystal SiC at depths of 10 and 25 nm. The possibility of machining SiC in the ductile mode was substantiated by post process analysis of the chips collected during machining and the surface profiles. The force data obtained during machining was recorded and compared later with the different depth of cuts. An investigation into the ability to single point …

Determination Of Stiffness Matrix Of Tapered Roller Bearings For Vibration Models, Jeeva Kumar

Masters Theses

The stiffness matrix of tapered roller bearings under radial and axial load conditions was evaluated using an analytical model and an experimental approach. An experimental test system was designed and manufactured to determine the radial stiffness of the bearing under combined axial and radial load conditions. A second fixture was designed to measure the stiffness of the bearing under pure axial load conditions. The stiffness coefficients determined have been compared with those obtained from the analytical model, OEM (Original Equipment Manufacturer) data and ABAQUS model (finite element analysis software).

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 …

Prediction Of Shaft Vibration Modes In A Geared Transmission System, Kevin W. Marsh

Masters Theses

During the development process of heavy-duty truck transmissions, specific gear designs (geometries) are created to meet load requirements and ratio coverage. Few tools are available to investigate the noise generating potential of these transmissions early in the design stages. This research describes the development and application of a software program that predicts transmission countershaft vibration modes. From simple gear and shaft geometries, the program calculates gear mesh forces and bearing forces then construct the system of equations to compute the shaft vibration modes. Because of the way the input data was structured, this software tool can also be used to …

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 …

Experimental Determination Of Convection Boiling Curves For Water And Ethylene Glycol In A Rectangular Channel With Localized Heating, Andrew T. O'Neill

Masters Theses

Convective boiling experiments were conducted to show the effects of velocity, pressure, and subcooling on both water and a water-ethylene glycol mixture. Boiling curves were obtained in a 30 mm wide by 20 mm high rectangular channel with an upward facing 20 mm wide by 30 mm long rectangular copper heater. The velocity ranged from 0.5 m/s to 4.0 m/s, the pressure ranged from 1.0 atm to 2.6 atm, and the subcooling ranged from 10°C to 50°C. The curves were generated with measured heat fluxes up to 100W/cm² . The inlet conditions of temperature, velocity, and pressure were maintained …

Development Of A Statistical Model For Process Control To Eliminate Sink Marks In Injection Molded Products, Kurt Frederick Hayden

Masters Theses

Customer demands for high-quality, defect-free injection-molded products are ever increasing. In order to satisfy these quality requirements, much effort is spent monitoring and controlling variable data such as cycle time, part weight, and dimensions. Attribute defects such as sink or splay are often overlooked in the development of process control systems. However, customers reject products because of these attribute defects. Industrial control systems based upon process variables and product design variables can detect conditions that may result in the molding of products with attribute defects. The systems can then correct the process prior to the molding of these defective products. …

Investment Casting Using Ice Patterns -- Solid Mold And Shell Mold Methods, Harish Jose

Masters Theses

"This thesis focuses on the development and implementation of the investment casting process using ice patterns. The traditional method of the investment casting process involves using wax patterns. Wax patterns tend to expand during the dewaxing process, and this causes stress on the shell wall which can eventually lead to the breaking of the wall. Ice patterns on the other hand shrink when heated. This is a very desirable property for the investment casting process. The process of dewaxing (dewatering) of ice patterns can be achieved by keeping the shells at room temperature, instead of heating the shell in an …

Application Of Laser Aided Manufacturing Process For Functionally Graded Thermal Barrier Coatings, Yashodhan Joshi

Masters Theses

"Laser Aided Manufacturing Process (LAMP) is a rapid prototyping process used to build three dimensional functional metal and ceramic parts. The process developed in the LAMP laboratory at University of Missouri-Rolla uses a 5-axis fadal CNC machine and a 2.5 KW Nd:YAG (TEM₀₀) Rofin Sinar laser. The laser power and metal/ceramic powder are the input along with auxiliary systems such as shielding gas delivery, RT data acquisition, coolant system. The hybrid process makes use of metal deposition and machining to obtain parts meeting design tolerances.

LAMP is used to improve upon the process of Thermal Barrier Coating (TBC) …

Characteristics Of Laser Forming Austenitic Stainless Steel Alloys, Jack Robert Pennuto

Masters Theses

"This thesis discusses the investigation of laser forming austenitic stainless-steel alloys for the development of free curve and complex shapes...Previous work in this area has focused on the development of single angle laser forming and process optimization for the development of multi-dimensional shapes. This thesis seeks to discuss the relationship of multiple parallel laser passes and any coupling effects that may exist for the class of austenitic stainless steels, including any metallurgical implications"--Abstract, page iii.

Effect Of Engine Operating Conditions On The Size And Morphology Of Diesel Particulate Emissions, Adam Neer

Masters Theses

"The size, morphology and volume fraction of sub-micron particulate matter emitted from a compression ignition (diesel) engine was investigated using thermophoretic sampling experiments followed by direct visual characterizations under transmission electron microscopy. Specifically, measurements were conducted at the exhaust of a 6059T John Deere, 5.9 L, 6 cylinder, turbocharged, direct injection diesel engine. The particles observed were composed of nearly spherical primary particles (spherules) that formed aggregates of various sizes and shapes. The size distributions of spherules and aggregates were separately measured to obtain the available surface area, which is crucial for estimating the environmental and health impact of particles. …