Mechanical Engineering Commons^™

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 …

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 …

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 …

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, …

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 …

Two-Dimensional Grain Boundary Percolation In Alloy 304 Stainless Steel, Brent L. Adams, John A. Basinger, David T. Fullwood, E. R. Homer

Faculty Publications

This work was supported by the MRSEC program of the National Science Foundation under Award Number DMR-0079996. An experimentally-obtained percolation threshold for high-angle random grain boundary networks in alloy 304 stainless steel is compared to thresholds predicted by percolation theory. A discrepancy occurs in the two values (0.46 experimental and 0.65 theoretical). Possible reasons for the discrepancy are explored. The grain boundary network appears to be composed of two distinct sub-networks, with the 'outer' network acting as the dominant contributor to the percolating paths.

Experimental Nonlinear Tracking Control For Nonholonomic Mobile Robots With Input Constraints, Timothy Mclain, Randal W. Beard, Wei Ren, Ji-Sang Sun

Faculty Publications

This paper presents experimental results of nonlinear trajectory tracking controllers for nonholonomic mobile robots with fixed-wing UAV-like input constraints. Programmed to emulate an unmanned air vehicle flying at constant altitude, a nonholonomic mobile robot is assigned to follow a desired trajectory to transition through a sequence of targets in the presence of static and dynamic threats. Two velocity controllers with input constraints are proposed for tracking control. Hardware results using these two velocity controllers are compared to simulation results of dynamic controllers based on nonsmooth backstepping to demonstrate the effectiveness of our approach.

Forest Fire Monitoring With Multiple Small Uavs, David W. Casbeer, Randal W. Beard, Timothy W. Mclain, Sai-Ming Li, Raman K. Mehra

Faculty Publications

Frequent and detailed updates of the development of a forest fire are essential for effective and safe fire fighting. Since a forest fire is typically inaccessible by ground vehicles due to mountainous terrain, small Unmanned Air Vehicles (UAVs) are emerging as a promising solution to the problem of monitoring large forest fires. In this paper we present an effective path planning algorithm for a UAV utilizing infrared images that are collected on-board in realtime. In order to demonstrate the effectiveness of our path planning algorithm in realistic scenarios, we implemented the forest fire propagation model EMBYR to simulate the time …

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 …

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. …

Electrothermomechanical Modeling Of A Surface-Micromachined Linear Displacement Microactuator, Christian D. Lott

Theses and Dissertations

The electrothermomechanical characteristics of an electrically-heated polycrystallinesilicon microactuator are explored. Using finite-difference techniques, an electrothermal model based on the balance of heat dissipation and heat losses is developed. For accurate simulation, the relevant temperature dependent properties from the microactuator material are included in the model. The electrothermal model accurately predicts the steady-state power required to hold position, and the energy consumed during the thermal transient. Thermomechanical models use the predictions of temperature from the electrothermal solution to calculate displacement and force from pseudo-rigid-body approximations and commercial finite-element code. The models are verified by comparing experimental data to simulation results of …

Hydrodynamic Drag And Flow Visualization Of Isotruss Lattice Structures, James T. Ayers

Theses and Dissertations

Hydrodynamic drag testing was conducted for eleven different configurations of IsoTruss® lattice structures. Flow visualization of prototypical IsoTruss® wind towers was also performed using Particle Image Velocimetry instrumentation. The drag test and flow visualization specimens included 6-node and 8-node configurations, single and double-grid geometries, thick and thin member sizes, smooth and rough surface finishes, a helical-only structure, and a smaller outer diameter test specimen. Three sets of hydrodynamic drag tests were conducted in a closed-circuit water tunnel: 1) orientation drag tests, 2) water velocity drag tests, and 3) height variation drag tests. The orientation drag tests measured the hydrodynamic drag …

All Hexahedral Meshing Of Multiple Source, Multiple Target, Multiple Axis Geometries Via Automatic Grafting And Sweeping, Matthew N. Earp

Theses and Dissertations

The development of algorithms for the automatic creation of finite element meshes composed entirely of hexahedra (all-hex) is an active area of research. All-hex meshes are desirable for their characteristic of high accuracy with a low node count. Sweeping is one of the most widely used algorithms for generating all-hex meshes. A limitation of sweeping, however, is that it can currently be applied only to prismatic or extruded geometry types. This thesis develops a method to combine sweeping with another algorithm known as "Grafting". Grafting adjusts the mesh on one volume to conform to a second volume. In this manner …

Phase Locked Flow Measurements Of Steady And Unsteady Vortex Generator Jets In A Separating Boundary Layer, Laura C. Hansen

Theses and Dissertations

Vortex generator jets (VGJs) have been found to be an effective method of active separation control on the suction side of a low pressure turbine (LPT) blade at low Reynolds numbers. The flow mechanisms responsible for this control were studied and documented in order to provide a basis for future improvements in LPT design. Data were collected using a stereo PIV system that enabled all three components of velocity to be measured. Steady VGJs were injected into a laminar boundary layer on a flat plate (non-separating boundary layer) in order to more fully understand the characteristics and behavior of the …

Determination Of Wall Thickness And Height When Cutting Various Materials With Wire Electric Discharge Machining Processes, Sangseop Kim

Theses and Dissertations

This thesis looks at the capabilities of cutting thin webs on Wire EDM machines that are difficult or impossible to machine using conventional methods. Covered is an investigation of how different material and web thickness affect the capability of machining thin-walled parts.

Five different metals are used for the test; Aluminum 6061 T6, Yellow Brass SS360, 420 Stainless Steel, D2 unheat-treated tool steel 25-30 RC, and D2 heat-treated tool steel 60-65 RC. The small parts were cut to a 6mm (0.2362 inch) height with six different wall thicknesses: 0.30mm (0.0118 inch), 0.25mm (0.0098 inch), 0.20mm (0.0078 inch), 0.15mm (0.0059 inch), …

A Tool Wear Comparative Study In Turning Versus Computer Simulation In 1018 Steel, Woodrow D. Miner

Theses and Dissertations

The material removal process uses cutting tools in order to produce the desired shape of the workpiece. Tool wear has been a problem for cutting tools, since cutting tools wear and break. Research has been accomplished in the tool wear field for tool life and more recently tool wear. The computer generation has created a method to simulate the material removal process. These computer simulations model the cutting tool reaction with the workpiece. Many of the simulation models use finite element analysis to calculate the reaction of the cutting tool. Different finite element models are being used throughout the world …

Dual-Stage Thermally Actuated Surface-Micromachined Nanopositioners, Neal B. Hubbard

Theses and Dissertations

Nanopositioners have been developed with electrostatic, piezoelectric, magnetic, thermal, and electrochemical actuators. They move with as many as six degrees of freedom; some are composed of multiple stages that stack together. Both macro-scale and micro-scale nanopositioners have been fabricated. A summary of recent research in micropositioning and nanopositioning is presented to set the background for this work. This research project demonstrates that a dual-stage nanopositioner can be created with microelectromechanical systems technology such that the two stages are integrated on a single silicon chip. A nanopositioner is presented that has two stages, one for coarse motion and one for fine …

Developing A Design Space Model Using A Multidisciplinary Design Optimization Schema In A Product Lifecycle Management System To Capture Knowledge For Reuse, Nathaniel Luke Fife

Theses and Dissertations

Parametric strategies for design automation and optimization can have a big impact on engineering design. When parametric tasks and optimization frameworks and methods are combined, theses strategies can be used to make up what is known as a multidisciplinary design optimization (MDO) schema. Knowledge of a design space can be modeled by using a MDO schema to represent the design process. However, current MDO frameworks used to create this schema lack the scope to capture enterprise wide knowledge for reuse and collaboration. Concurrent with the development of MDO, many companies are moving toward increased use of product lifecycle management (PLM). …

Statistical Investigation Of Friction Stir Processing Parameter Relationships, Jonathan H. Record

Theses and Dissertations

Friction Stir Welding (FSW) is an emerging joining technology in which basic process understanding is still inadequate. Knowledge of FSW parameter relationships is needed to better understand the process and implement proper machine control. This study utilized a 3-factor, 3-level factorial design of experiments to investigate relationships between key process inputs and measured output parameters. All experiments utilized 7075-T7 aluminum and a threaded pin tool with a 25.4 mm shoulder diameter, 4.76 mm pin length, and 7.9 mm pin diameter. Spindle speed, feed rate, and tool depth were varied throughout 54 welds while X, Y, and Z forces, X torque, …

Simulation-Based Design Under Uncertainty For Compliant Microelectromechanical Systems, Jonathan W. Wittwer

Theses and Dissertations

The high cost of experimentation and product development in the field of microelectromechanical systems (MEMS) has led to a greater emphasis on simulation-based design for increasing first-pass design success and reliability. The use of compliant or flexible mechanisms can help eliminate friction, wear, and backlash, but compliant MEMS are sensitive to variations in material properties and geometry. This dissertation proposes approaches for design stage uncertainty analysis, model validation, and robust optimization of nonlinear compliant MEMS to account for critical process uncertainties including residual stress, layer thicknesses, edge bias, and material stiffness. Methods for simulating and mitigating the effects of non-idealities …

The Purposes And Evaluation Methods For State Residential General Contractor Licensing, James Ellis Fenn

Theses and Dissertations

The main topic in the licensing debate is whether licensing affects construction quality. Available literature and previous studies indicate that it does not. The real question is not whether licensing improves quality, but whether the improving quality is the actual purpose of licensing. There is little information available on the purpose of licensing as defined by state licensing departments as well as a general lack of information on how states evaluate whether licensing is fulfilling the intended purpose. In order to effectively resolve some of the issues surrounding the construction licensing debate, the true purpose of licensing and the methods …

Finite Approximations To The Second-Order Properties Closure In Single Phase Polycrystals, Brent L. Adams, Xiang Gao, Surya R. Kalidindi

Faculty Publications

This work was supported at Brigham Young University and Drexel University by a grant from the US Army Research Office, through the Metallurgy Program headed by Dr. David Stepp. Extension of the first-order theory of microstructure design to considerations of morphological texture is addressed in this paper. The main challenges include the r-interdependence of the 2-point correlation functions of lattice orientation, construction of the corresponding microstructure hull, and its corresponding properties closure(s). It is shown that the correlation functions can be expressed in terms of an intermediate construct, called the texture function; the correlation functions have quadratic dependence in the …

Real-Time Evaluation Of Vision-Based Navigation For Autonomous Landing Of A Rotorcraft Unmanned Aerial Vehicle In A Non-Cooperative Environment, Dale D. Rowley

Theses and Dissertations

Landing a rotorcraft unmanned aerial vehicle (RUAV) without human supervision is a capability that would significantly broaden the usefulness of UAVs. The benefits are even greater if the functionality is expanded to involve landing sites with unknown terrain and a lack of GPS or other positioning aids. Examples of these types of non-cooperative environments could range from remote mountainous regions to an urban building rooftop or a cluttered parking lot. The research of this thesis builds upon an approach that was initiated at NASA Ames Research Center to advance technology in the landing phase of RUAV operations. The approach consists …

Fabrication Of Hollow Waveguides With Sacrificial Aluminum Cores, John P. Barber, Donald B. Conkey, Jeffrey Ryan Lee, Neal B. Hubbard, Larry L. Howell, Aaron R. Hawkins, Gongliang Yin, Holger Schmidt

Faculty Publications

We have developed a process to fabricate dielectric waveguide structures with long hollow cores formed by etching a sacrificial core material. The process is compatible with other planar silicon fabrication techniques. Using aluminum as the sacrificial material, we have investigated fabrication limits and design parameters that determine mechanical integrity of the waveguides. Internal pressure due to the production of gaseous compounds during the core removal process was identified as the yield-limiting factor. A mechanical model based on finite element analysis and confirmed by experiment, predicts ultimate pressures sustainable by these structures. Waveguides less than 10 m wide with 2- m-thick …

Dynamic Reconfigurable Machine Tool Controller, Wei Li

Theses and Dissertations

This dissertation presents a dynamic reconfigurable control strategy based on the Direct Machining And Control (DMAC) research at Brigham Young University. A reconfigurable framework is proposed which will allow a machine tool to be controlled by a variety of applications and control laws. This Reconfigurable Mechanism for Application Control (RMAC) paradigm uses a hierarchical architecture to configure a mechanism into a device driver for direct control by an application like CAD/CAM. The RMAC paradigm is one of a mechanism device driver assigned to each mechanism class or model, and uses only the master model to control the mechanism. The traditional …

Autonomous Vehicle Technologies For Small Fixed-Wing Uavs, Randal Beard, Derek Kingston, Morgan Quigley, Deryl Snyder, Reed Christiansen, Walt Johnson, Timothy Mclain, Michael A. Goodrich

Faculty Publications

The objective of this paper is to describe the design and implementation of a small semi-autonomous fixed-wing unmanned air vehicle. In particular we describe the hardware and software architectures used in the design. We also describe a low weight, low cost autopilot developed at Brigham Young University and the algorithms associated with the autopilot. Novel PDA and voice interfaces to the UAV are described. In addition, we overview our approach to real-time path planning, trajectory generation, and trajectory tracking. The paper is augmented with movie files that demonstrate the functionality of the UAV and its control software.