Mechanical Engineering Commons^™

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 …

Robust Initial Matching Of Free-Form Objects Represented By Point Cloud Data, Nimun A. Jahangir

Digitized Theses

No abstract provided.

Incorporating Computational Fluid Dynamics Into The Preliminary Design Cycle, Jonathan Knighton Shelley

Theses and Dissertations

Industry is constantly looking for ways to bring new or derivative products to market in the shortest amount of time for the least amount of money. To accomplish this, Industry has adopted Computer Aided Engineering (CAX) tools that perform structural, flow, manufacturing, and cost analysis. The way in which a company utilizes these CAX tools can determine the success of these new products. One of these tools that Industry often struggles with in the preliminary design of a product is Computational Fluid Dynamics (CFD). Some of the challenges presented by CFD are the time it takes to create a CAD …

Nesting Automated Design Modules In An Interconnected Framework, Jared Matthew Young

Theses and Dissertations

This thesis seeks to extend the PDG methodology by developing a generalized formal method for nesting PDGs in an interconnected system. A procedure for decomposing an individual PDG into reusable modules will be defined and a software architecture will be presented which takes advantage of these reusable modules. This method breaks the PDG structure into discrete elements known as PDG objects, PDG modules and PDG services. Each of these elements forms a distinct unit of reuse and each can be seen as a "little" PDG. Two different industrial implementations of this method are presented. These examples show that it is …

Experimental And Numerical Investigation Of Tool Heating During Friction Stir Welding, Joshua L. Covington

Theses and Dissertations

The heat input to the tool has been investigated for friction stir welding (FSW) of aluminum alloy AL 7075-T7351 over a wide range of process operating parameters using a combined experimental/numerical approach. In a statistical Design of Experiments fashion, 54 experimental welds (bead-on-plate) were performed at 27 different parameter combinations. Measured outputs during each of the welds included forces in all three coordinate directions and internal temperature of the rotating tool at three locations near the tool/workpiece interface. The heat input to the tool was also identified for each weld using infrared imaging temperature measurement techniques and the portion of …

Development Of A Weatherproof Windscreen For A Microphone Array, Jeffrey R. Hill

Theses and Dissertations

Microphone windscreens are typically used to reduce the noise associated with wind flowing over a microphone diaphragm by reducing the velocity of the airflow. While most windscreens are effective at reducing this noise, they do not protect the microphone from many natural elements, such as moisture, sand, and other small particles. The focus of this research was to design a windscreen that protects an array of five microphones located around a 4.5-inch diameter cylinder from these natural elements. The design goals were to have a wind noise attenuation of at least 8 dB, an insertion loss of less than 1 …

Visualizing And Interacting With Externally Coupled Engineering Analysis Results, Paul Frederick Nelson

Theses and Dissertations

Visualizing and interacting with engineering analysis results can provide valuable insights into a system's performance and aid in engineering decision-making. Currently, the majority of analysis codes are developed as isolated solutions focusing only on the most prominent physical influence to a system, such as thermal, structural, fluid, etc. Frequently, more than one of these physical influences combined to force engineers to evaluate complex, coupled systems. Coupled analysis codes are becoming more common place tools for engineers demanding high fidelity simulations of complex systems. External code coupling solutions are emerging to permit generic coupling of separate, world class CAE solvers thus …

Integrating Value Stream Mapping And Simulation, Michelle E. Scullin

Theses and Dissertations

An important principle in Lean manufacturing, value stream mapping (VSM) can be helpful in understanding how process flow and information flow affect each other. A VSM is a static picture of a process that allows the user to see where value is added into the value stream. Simulation is used to evaluate the behavioral issues of processes. In a manufacturing realm this means simulation shows how each operation affects other operations so determinations can be made about where bottlenecks or other problems exist in the process. Theoretically, the integration of VSM and Simulation can aide in process improvement by showing …

Vision-Based Target Localization From A Small, Fixed-Wing Unmanned Air Vehicle, Joshua D. Redding

Theses and Dissertations

Unmanned air vehicles (UAVs) are attracting increased attention as their envelope of suitable tasks expands to include activities such as perimeter tracking, search and rescue assistance, surveillance and reconnaissance. The simplified goal of many of these tasks is to image an object for tracking or information-gathering purposes. The ability to determine the inertial location of a visible, ground-based object without requiring a priori knowledge of its exact location would therefore prove beneficial. This thesis discusses a method of localizing a ground-based object when imaged from a fixed-wing UAV. Using the target's pixel location in an image, with measurements of UAV …

Ortho-Planar Mechanisms For Microelectromechanical Systems, Craig P. Lusk

Theses and Dissertations

A method for representing the design space of ortho-planar mechanisms has been developed. The method is based on the Theorem of Equality of Orientation Set Measures (TEOSM) which allows mechanisms to be represented by points in an abstract space. The method is first developed for single loop planar folded mechanisms with revolute joints, and later extended to mechanisms with prismatic joints and to spherical folded mechanisms. Functions which assign a value to each point in design space can be used to describe classes of mechanisms and evaluate their utility for MEMS design. Additionally, this work introduces the use of spherical …

An Analysis Of Microstructure And Corrosion Resistance In Underwater Friction Stir Welded 304l Stainless Steel, Tad Dee Clark

Theses and Dissertations

An effective procedure and parameter window was developed for underwater friction stir welding (UWFSW) 304L stainless steel with a PCBN tool. UWFSW produced statistically significant: increases in yield strengths, decreases in percent elongation. The ultimate tensile strength was found to be significantly higher at certain parameters. Although sigma was identified in the UWFSWs, a significant reduction of sigma was found in UWFSWs compared to ambient FSWs. The degree of sensitization in UWFSWs was evaluated using double loop EPR testing and oxalic acid electro-etched metallography. Results were compared to base metal, ambient FSW, and arc welds. Upper and lower sensitization localization …

Attribution Standardization For Integrated Concurrent Engineering, Tyson J. Baker

Theses and Dissertations

Product design is a creative process, often subject to rapid and numerous design change requirements. To facilitate geometric redesign iterations, Parametric Computer-Aided Design CAD) systems were introduced. To manage the numerous product design iterations produced by parametric CAD systems, Product Data Management (PDM) systems were developed to capture, document, and manage each product revision. PDM has proved effective thus far at managing design history. However, PDM is built upon database management systems (DBMS), which have the capability of doing far more than simply managing product revision history. Product data consists not only of the physical geometry used to describe it, …

Load Interaction Effects On Fatigue Crack Growth, Stoyan Ivanov Stoychev

Dissertations

Load excursions, in the form of tensile and compressive overloads are known to produce interaction effects during subsequent constant amplitude loading. In this work, the fatigue crack growth and crack closure levels, under both constant amplitude and variable amplitude loading, are investigated in the aluminium-lithium alloy 2090-T84, and the aluminium alloys 2024-T351 and 7150-T651. The crack closure measurements were obtained using both a crack tip opening displacement (CTOD) gauge and a crack mouth opening displacement (CMOD) gauge.

Fatigue crack growth tests were performed on specimens of thickness 1.6mm, 3mm, 6mm and 14mm. Tests were performed at load ratios of 0.1 …

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 …

Insulator Charging In Rf Mems Capacitive Switches, Jay F. Kucko

Theses and Dissertations

While capacitive radio frequency microelectromechanical (RF MEM) switches are poised to provide a low cost, high isolation, low power alternative to current RF switch technologies, there are still reliability issues limiting switch lifetime. Previous research identified insulator charging as a primary cause of switch failure. Changes in switch pull-in and release voltages were measured to provide insight into the mechanisms responsible for charging and switch failure. A spatial and temporal dependent model was developed to describe silicon nitride's time-dependent charging as a function of applied bias. This model was verified by applying constant biases to metal-silicon nitride-silicon capacitors and tracking …

Evaporating Cross Flow Spray Jets In Gas-Solid Circulating Fluidized Bed, Tong Hoon Lee

Dissertations

Three-phase flow of solid-gas suspension with liquid spray is found in many industrial applications, including fluidized catalytic cracking in petroleum refinery process, and wet scrubbing process. This dissertation study is aimed to understand the gas-solid-liquid three-phase flow structure, phase interactions and transport in a gas-solid circulating fluidized bed where an evaporating cross-flow liquid spray jet from a rectangular nozzle with a fan angle is injected. The investigation is based on both numerical and experimental approaches. The numerical study is for detailed field descriptions of the flow structure, phase interaction and distributions whereas the experimental study is for simulation validations. The …

Direct Numerical Simulations And Experimental Investigation Of Dielectrophoresis, Arun Thankamony John-Kadaksham

Dissertations

This dissertation deals with the numerical and experimental studies of the phenomenon of dielectrophoresis, i.e., the motion of neutral particles in nonuniform electric fields. Dielectrophoresis is the translatory motion of neutral particles suspended in a dielectric medium when they are subjected to an external nonuniform electric field. The translatory motion occurs because a force called the dielectrophoretic force, which depends on the spatial variation of the electric field, acts on the particles. As the generation of force involves no moving parts and the particles can be moved without touching them, dielectrophoresis can be used in many applications, including manipulation and …

Simulation Of Creep In Nickel Based Single Crystal Superalloys, Yunhong Pang

Dissertations

Nickel based single crystal Superalloys are finding wide spread use in high temperature gas turbines and other similar applications because of their superior high-temperature strength and creep properties as compared to the other materials. This is due to two factors: solid solution and precipitation strengthening of the gamma (γ) and gamma prime (γ') phases, and the elimination of grain boundaries. Creep of Nickel based single crystal Superalloys are caused by two primary mechanisms, dislocation creep and diffusion creep. Several factors that affect the creep life of Nickel based single crystal Superalloys are the specific microstructure, stress, temperature and rafting. Also, …

Gas Fluidization Of Nanoparticles, Qun Yu

Dissertations

The primary objective of this study is to perform a systematic investigation on the gas fluidization of various nanoparticle agglomerates. Firstly, the gas fluidization characteristics and regime classifications without any additional external force fields are identified using both experimental measurements and modeling. Secondly, the effect of introducing certain external force fields on nanoparticle fluidization is experimentally investigated. Two external force fields were applied: sound waves from a loud speaker (acoustic assistance) and in-bed magnets that were excited by an external oscillating magnetic field (magnetic assistance). Thirdly, exploratory experimental research on the use of nanoparticle agglomerates as a granular filtration media …

Microparticle Influenced Electroosmotic Flow, John M. Young

Theses and Dissertations

The influence of microparticles on electroosmotic flow was investigated experimentally and numerically. Experiments were conducted using four different particle types of varying chemical composition, surface charge and polarity. Each particle type was tested at five different volume fractions ranging from 0.001 – 0.025. With a constant applied electric field, positively charged particles enhanced the electroosmotic flow by as much as 850%. The enhancement depended on particle composition, size and concentration. For negatively charged particles, the bulk electroosmotic flow was retarded with the largest reductions being 35%. This occurred for the greatest negative paricle concentration studied. A final experimental study utilizing …

The Sensitivity Of Aircraft Emergency Locator Transmitters To Non-Distress Impact Events, Christopher John Molnar

Theses and Dissertations

Emergency locator transmitters are radio beacons that help locate aircraft in distress and are required on many aircraft, primarily general aviation aircraft. The purpose of an emergency locator transmitter is to assist SAR teams in rapidly locating downed aircraft so aid can be provided to the pilot and passengers. The first emergency locator transmitters, still in use today, were found to have crash activation rates of only twenty-five percent (25%). This means that three out of every four crashes are not detected by these devices. Newer emergency locator transmitters were found to have crash activation rates of seventy-three percent (73%) …

The Accuracy Of Energy-Based Crash Reconstruction Techniques Using Event Data Recorder Measurements, Peter Niehoff

Theses and Dissertations

In the field of accident investigation, a vehicle's delta-V is commonly used to quantify the severity of a collision. Delta-V is defined as the impulsive change in vehicle velocity caused by a collision. Often, the method used to obtain delta-Vs in real-world collisions is estimation based on post-collision vehicle crush measurements. However, these estimates have been known to result in large errors. The recent advent of Event Data Recorder (EDR) technology has provided engineers with measured delta-Vs from real-world collisions. These accurate measurements were the basis for several studies conducted in this thesis.

As EDRs are a new technology, little …

Development Of An Energy-Based Nearfield Acoustic Holography System, Michael C. Harris

Theses and Dissertations

Acoustical-based imaging techniques have found merit in determining the behavior of vibrating structures. These techniques are commonly used in numerous applications to obtain detailed noise source information and energy distributions on source surfaces. This thesis focuses on the continued development of the nearfield acoustic holography (NAH) approach. Conventional NAH consists of first capturing pressure data on a two-dimensional conformal measurement contour in the nearfield of the radiating source. These data are then propagated back to the vibrating structure to obtain the normal velocity profile on the source surface. With the source surface velocity profile known, the acoustic pressure, particle velocity, …

Sound Quality Analysis Of Sewing Machines, James J. Chatterley

Theses and Dissertations

Sound quality analysis is a tool designed to help determine customer preferences, which can be used to help the designer improve product quality. Many industries desire to know how the consuming public perceives their product, as this affects the product life and success. This research investigates which of the six sewing machines provided by Viking Sewing Machine Group (VSM group) consumers find most acoustically appealing. The sound quality analysis methods used include both jury based listening tests and quantitative sound quality metrics from empirical equations. The results from both methods are completely independent and are shown to have a very …

Effects Of Fuel Molecular Structure And Composition On Soot Formation In Direct-Injection Spray Flames, Kenth Ingemar Svensson

Theses and Dissertations

Numerous investigations have been conducted to determine the effect of fuel composition and molecular structure on particulate emissions using exhaust gas analysis, but relatively few measurements have been obtained in-cylinder or under conditions where fuel effects can be isolated from other variables. In this work, dimethoxymethane was used as the base fuel to produce a non-sooting flame in a constant volume combustion vessel at 1000 K, and a density of 16.6 kg/m3. A second fuel was then added incrementally to determine an incipient soot limit. Line-of-sight extinction measurements were used as the primary diagnostic tool to determine if a correlation …

Development Of A Five-Axis Machining Algorithm In Flat End Mill Roughing, Michael Blaine Thompson

Theses and Dissertations

To further the research done in machining complex surfaces, Jensen [1993] developed an algorithm that matches the normal curvature at a point along the surface with the resultant radius formed by tilting a standard flat end mill. The algorithm called Curvature Matched Machining (CM2) is faster and more efficient than conventional three-axis machining [Jensen 1993, Simpson 1995 & Kitchen 1996]. Despite the successes of CM2 there are still many areas available for research. Consider the machining of a mold or die. The complex nature of a mold requires at least 20-30 weeks of lead time. Of those 20-30 weeks 50% …

Development And Application Of A New Modeling Technique For Production Control Schemes In Manufacturing Systems, Bashar Hafez Sader

Theses and Dissertations

This dissertation presents dynamic system models of continuous manufacturing systems based on analogies with electrical systems. The developed modeling technique has the capability to explicitly specify production control schemes including control points, material and information flow paths, and logical operations. The model provides standard graphical representations and governing equations to describe both the steady state and transient responses of continuous manufacturing systems. For deterministic systems, these equations can be solved to get closed-form solutions. For stochastic systems, numerical solutions can be obtained for any probabilistic distribution. The electrical analogs provide an excellent tool to model control signals and logical operations. …