Civil and Environmental Engineering Commons^™

A Finite Element Simulation Of Temperature And Material Flow In Fricton Stir Welding, Mark J. Lasley

Theses and Dissertations

The purpose of this research was to use the Transvalor S.A. product, Forge3, to develop a finite element simulation of the friction stir welding process that improves the predictability of temperature evolution and material flow within the plunge portion of the process. Previous modeling created more heating within the billet than experimental results, probably due to the simplification of the simulation with adiabatic boundary conditions. More realistic tooling temperatures were included in this model as these affect heat evolution which is a determining factor in microcrystalline growth. These results were validated by experimental efforts using a billet and tooling instrumented …

A Method For Winding Advanced Composites Of Unconventional Shapes Using Continuous And Aligned Fibers, Abraham K. Allen

Theses and Dissertations

Advanced composites are extremely strong, rigid, and light, even when compared with advanced metals. Advanced composites are replacing high-tech metals as the material of choice for aerospace engineering. However, the processes used to manufacture advanced composites generally lose some of the properties of the materials by their process limitations.

One process that keeps the theoretically awesome qualities of the composite materials in tact is filament winding. Filament wound parts are used as rocket shells, bicycle frame tubes, drive shafts, pressure vessels, etc. Filament winding is an automated process and makes reliable parts to close tolerances. If a straight tube were …

The Effectiveness Of Computer-Based Tutorials In Learning Computer-Aided Design Methods For Tool Design Procedures, Andrew Moroni Hall

Theses and Dissertations

Throughout the past twenty-five years the process of designing and manufacturing a product has been revolutionized by the integration of Computer Aided Design (CAD). Although three-dimensional solid modeling, or 3-D CAD offers a better representation of the product in a virtual environment, it can be complicated and difficult to learn. Tutorials have been developed to assist manufacturing tool design student in the learning of 3-D CAD principles as they apply to tool design. This study seeks to test the effectiveness of those tutorials. A BYU tool design class was divided into two groups according to their assigned laboratory time. The …

Improved Signal Integrity In Ieee 1149.1 Boundary Scan Designs, Efren De Jesus Rangel Taboada

Theses and Dissertations

This work is an analysis of solutions to problems derived from inherent timing and signal integrity issues in the use and application of the IEEE 1149.1 Standard at the board level in conjunction with its test system. Setup or hold times violations may occur in a boundary scan chain using IEEE 1149.1 compliant devices. A practical study of the TDI-TDO scan data path has been conducted to show where problems may arise in relationship to a particular board topology and test system. This work points to differences between passing and failing scan path tests for problem characterization. Serial data flow …

The Benefit Of Using Simulation To Improve The Implementation Of Lean Manufacturing Case Study: Quick Changeovers To Allow Level Loading Of The Assembly Line, Jack J. Mcclellan

Theses and Dissertations

In today's competitive manufacturing environment, companies are constantly looking for ways to improve. Because of this, many companies are striving to become "lean" by implementing lean manufacturing, which is a difficult process. To aid in the implementation of lean manufacturing, simulation was used to reduce the trial-and-error period of lean manufacturing and find to optimum approach to implement the lean manufacturing principle. In this research, a case study of implementing level loading of the production schedule for BullFrog International, L.C. will be examined. To make it possible to implement level loading, the thermo-former machine at the beginning of the operations …

A Review Of Setup Practices And Procedures For Creating Ieee 802.11 Wireless Community Networks, Jae M. Theobald

Theses and Dissertations

IEEE 802.11 wireless networking equipment has made it possible to bridge the last mile for new broadband internet service providers. Inexpensive wireless networking equipment and high gain antennas enable high speed internet delivery at a fraction of the cost of installing or upgrading land lines for cable or DSL services. Based on this research, a guide of general practices and procedures is proposed for designing, installing, and maintaining a reliable wireless community area network. Included tests have provided performance results for several types of wireless antennas (including wire grid parabolic dishes, Yagi and Vagi styles, and echo backfire), wireless bridges, …

Conformal Refinement Of All-Hexahedral Finite Element Meshes, Nathan Harris

Theses and Dissertations

Mesh adaptation techniques are used to modify complex finite element meshes to reduce analysis time and improve accuracy. Modification of all-hexahedral meshes has proven difficult to the unique connectivity constraints they exhibit. This thesis presents an automated tool for local, conformal refinement of all-hexahedral meshes based on the insertion of multi-directional twist planes into the spatial twist continuum. The contributions of this thesis are (1) the ability to conformally refine all entities of an all-hexahedral element mesh, (2) the simplification of template insertion to multi-directional refinement. The refinement algorithm is divided into single hex sheet operations, where individual refinement steps …

Coordinated Regional And City Planning Using A Genetic Algorithm, Michael B. Lowry

Theses and Dissertations

Improved methods of planning are needed to deal with today's issues of traffic congestion, sprawl, and loss of greenspace. Past research and recent legislation call for new methods that will consider a regional perspective. Regional planning is challenged with two difficult questions:

1.Is it possible to achieve regional goals without infringing upon the local autonomy of city planners?

2.Is it possible to objectively analyze the thousands, even millions, of land use and transportation plans to find the best design?

Metropolitan regions across the country have made great efforts to answer the first question. Unfortunately, effective methods for harmonizing the goals …

The Contextable: Building And Testing An Intelligent, Context-Aware Kitchen Table, Daniel Matthew Hoopes

Theses and Dissertations

The purpose of this thesis was to design and evaluate The ContexTable, a context-aware system built into a kitchen table. After establishing the current status of the field of context-aware systems and the hurdles and problems being faced, a functioning prototype system was designed and built. The prototype makes it possible to explore established, untested theory and novel solutions to problems faced in the field.

Floodplain Risk Analysis Using Flood Probability And Annual Exceedance Probability Maps, Christopher M. Smemoe

Theses and Dissertations

This research presents two approaches to determining the effects of natural variability and model uncertainty on the extents of computed floodplain boundaries. The first approach represents the floodplain boundary as a spatial map of flood probabilities -- with values between 0 and 100%. Instead of representing the floodplain boundary at a certain recurrence interval as a single line, this approach creates a spatial map that shows the probability of flooding at each point in the floodplain. This flood probability map is a useful tool for visualizing the uncertainty of a floodplain boundary. However, engineers are still required to determine a …

Full-Scale Lateral-Load Tests Of A 3x5 Pile Group In Soft Clays And Silts, Jeffrey L. Snyder

Theses and Dissertations

A series of static lateral load tests were conducted on a group of fifteen piles arranged in a 3x5 pattern. The piles were placed at a center-to-center spacing of 3.92 pile diameters. A single isolated pile was also tested for comparison to the group response. The subsurface profile consisted of cohesive layers of soft to medium consistency underlain by interbedded layers of sands and fine-grained soils. The piles were instrumented to measure pile-head deflection, rotation, and load, as well as strain versus pile depth.

Influence Of Consolidation And Interweaving On Compression Behavior Of Isotruss™ Structures, Steven Matthew Hansen

Theses and Dissertations

Composite IsoTruss™ structures incorporate intersecting longitudinal and helical members. At the intersections, the fiber tows can be interwoven to achieve mechanical interlocking for increased joint integrity. Interlocking introduces gaps and curvilinear fiber paths similar to the crossovers in filament-wound structures, potentially facilitating local delamination within the members, thus reducing the strength and/or damage tolerance of the structure. Optimizing the interlocking pattern at the joints along with efficient consolidation minimizes these effects.

Joint specimens were fabricated using a specially designed machine. Specific tow intersection patterns at the joint were: 1) Completely encapsulating the longitudinal member with the tows of the helical …

A Descriptive Performance Model Of Small, Low Cost, Diskless Beowulf Clusters, Curtis R. Nielson

Theses and Dissertations

Commodity supercomputing clusters known as Beowulf clusters, have become a low cost alternative to traditional supercomputers. Beowulf clusters combine inexpensive computers and specialized software to achieve supercomputing power. The processing nodes in a diskless Beowulf cluster do not have a local hard disk unlike the nodes in most commodity clusters. Research has provided performance information for diskless clusters built with expensive, high performance equipment. Beowulf clusters use commodity off-the-shell hardware, and little information is available about their performance. This research includes the construction of several diskless Beowulf clusters. Using the NAS Parallel Benchmarks, the performance of these clusters was measured. …

Efficacy Of Speed Monitoring Displays In Increasing Speed Limit Compliance In Highway Work Zones, Jeanne Marie Bowie

Theses and Dissertations

Safety in highway work zones has become a concern among Departments of Transportation (DOTs) throughout the country as the highway network has begun to age and more maintenance and construction work has been necessary. Safety in highway work zones is more compromised than in other areas for two reasons. First, the construction workers are near traveling vehicles as they perform their already dangerous work, increasing the risk of an accident. Second, the highway user is at increased risk because of the increase in roadside obstacles, because other vehicles are more likely to act in unpredictable ways (such as sudden braking …

Building Solid Models From Boreholes And User-Defined Cross-Sections, Alan M. Lemon, Norman L. Jones

Faculty Publications

Solid models of geologic structures are useful tools for geologists and engineers. Solid models completely and unambiguously define the stratigraphy for the site being modeled, including complex boundaries and embedded seams. Past research has focused on the “set operations” approach to create solid models. Whereas the set operations approach is flexible, it requires significant user intervention and is therefore difficult to use. A simple approach for generating solid models from borehole data, called the horizons method, is presented. The horizons method can be used to build solids directly from borehole data with minimal user intervention. The user first assigns horizon …

Sculpting: An Improved Inside-Out Scheme For All Hexahedral Meshing, Kirk S. Walton

Theses and Dissertations

Generating all hexahedral meshes on arbitrary geometries has been an area of important research in recent history. Hexahedral meshes have advantages over tetrahedral meshes in structural mechanics because they provide more accurate results with fewer degrees of freedom. Many different approaches have been used to create all-hexahedral meshes. Grid-based, inside-out, or superposition meshing all refer to a similar meshing approach that is a very common mesh generation technique. Grid-based algorithms provide the ability to generate all hexahedral meshes by introducing a structured mesh that bounds the complete body modeled, marking hexahedra to define an interior and exterior mesh, manipulating the …

Modification Of All-Hexadedral Finite Element Meshes By Dual Sheet Insertion And Extraction, Michael J. Borden

Theses and Dissertations

The development of algorithms that effectively modify all-hexahedral finite element mesh is currently an active area of research. Mesh modification can be used to improve mesh quality reduce the time required to mesh a model, and improve the finite element analysis results. However, general modification of all-hexahedral meshes has proven difficult because of the global effects of local modifications. This thesis explains the global constraints on modifying all-hexahedral meshes and then presents three mesh modification techniques that make it possible to do local modifications while accounting for the global effects. These techniques are sheet insertion, sheet extraction, and mesh cutting. …

Surfacing Splicing: A Method Of Quadrilateral Mesh Generation And Modification For Surfaces By Dual Creation And Manipulation, Benjamin Todd Grover

Theses and Dissertations

The effective generation high quality quadrilateral surface meshes is an area of important research and development for the finite element community. Quadrilateral elements generally lead to more efficient and accurate finite results. In addition, some all hexahedral volume meshing algorithms are based on an initial quadrilateral mesh surface mesh that has specific connectivity requirements. This thesis presents a new and unique procedure named "Surfaced Splicing". Surface Splicing allows for the generation of all quadrilateral surface meshes as well as the ability to edit these meshes via the dual. The dual contains the same data as the mesh but, unlike the …

Using Transition Probability Geostatistics With Modflow, Norman L. Jones, J. R. Walker, S. F. Carle

Faculty Publications

This paper describes a technique for applying the transition probability geostatistics method for stochastic simulation to a MODFLOW model. Transition probability geostatistics has several advantages over traditional indicator kriging methods, including a simpler and more intuitive framework for interpreting geological relationships and the ability to simulate juxtapositional tendencies such s fining-upwards sequences. The indicator arrays generated by the transition probability simulation are converted to layer elevation and thickness arrays for use with the new Hydrogeologic Unit Flow (HUF) package in MODFLOW 2000. This makes it possible to preserve complex heterogeneity while using reasonably sized grids.

Fast Algorithm For Generating Sorted Contour Strings, Norman L. Jones, Michael J. Kennard, Alan K. Zundel

Faculty Publications

Automatic generation of contours for graphical display and map plotting has been studied extensively since the early days of computing. The individual segments making up a contour line are often determined by subdividing the object of interest into small triangles and computing the contours assuming a linear variation on each triangle. However, efficient storage of contour data and the need to place labels (automatically) or to smooth the contours require that the contours be generated in continuous strings of segments. A simple approach to generate such strings is to sort the randomly generated contour segments. Since sorting can be time-consuming, …

Managing Temporal Data In A Comprehensive Modeling Environment, Norman L. Jones, E. James Nelson, Colby T. Manwaring

Faculty Publications

Numerous graphical pre- and post-processors have been developed for numerical modeling. Many of these systems support numerical models that can be used for both steady state and transient simulations. Dealing with transient data can be particularly difficult in such an environment due to the differing time scales and units associated with transient field data and boundary conditions. A data model and a set of functions are presented in this paper as a simple, yet powerful strategy for managing temporal data in a comprehensive modeling environment. The strategy makes it possible to seamlessly integrate multiple types of transient data and convert …

Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr

Theses and Dissertations

Finite element analysis depends greatly upon a high-quality mesh to be able to provide reasonably accurate answers to engineering problems. Models that need to be analyzed using finite element analysis are becoming increasingly more complex, and correspondingly harder to mesh with good quality. Skew is one quality metric which can cause problems with finite element analyses. This thesis explains how skew is calculated, discusses two common sources of skew: multiply-linked surfaces with interval constraints, and biased edge meshes. Two methods of lessening skew in surface meshes are then presented: the skew control algorithm, and the curve morphing algorithm. These algorithms …

Interval Matching And Control For Hexahedral Mesh Generation Of Swept Volumes, Jason F. Shepherd

Theses and Dissertations

Surface meshing algorithms require certain relationships among the number of intervals on the curves that bound the surface. Assigning the number of intervals to all of the curves in the model such that all relationships are satisfied is called interval assignment. Volume meshing algorithms also require certain relationships among the numbers of intervals on each of the curves on the volume. These relationships are not always captured by surface meshing requirements. This thesis presents a news technique for automatically identifying volume constraints. In this technique, volume constraints are grouped with surface constraints and are solved simultaneously. A sweepable volume has …

Resolving Problems In Engineering Ethics: Precept And Example, Joel C. Adair

Theses and Dissertations

This thesis has served to accomplish several objectives. First, a foundation was laid for the consideration of ethical factors in an engineering context. This was done by first establishing the need for ethical judgement in the engineering disciplines. A summary of several significant classical ethical theories followed, providing several tools with which to evaluate decisions that have ethical implications. Finally, the conclusion was made that the best framework for making ethical decisions is found in the application of the virtues espoused by the gospel of Jesus Christ.

Local Refinement Of Three-Dimensional Finite Element Meshes, M. L. Staten, Norman L. Jones

Faculty Publications

Mesh refinement is an important tool for editing finite element meshes in order to increase the accuracy of the solution. Refinement is performed in an iterative procedure in which a solution is found, error estimates are calculated, and elements in regions of high error are refined. This process is repeated until the desired accuracy is obtained.

Much research has been done on mesh refinement. Research has been focused on two-dimensional meshes and three-dimensional tetrahedral meshes ([1] Ning et al. (1993) Finite Elements in Analysis and Design, 13, 299–318; [2] Rivara, M. (1991) …

A Comprehensive Modeling Environment For The Simulation Of Groundwater Flow And Transport, S. J. Owen, Norman L. Jones, J. P. Holland

Faculty Publications

A comprehensive graphical modeling environment has been developed to address the needs of the computer simulation of groundwater flow and transport. The Department of Defense Groundwater Modeling Systems (GMS), developed at the Engineering Computer Graphics Laboratory at Brigham Young University, is part of a multi-year project funded through the Department of Defense, Department of Energy and Environmental Protection Agency. GMS is a graphically based software tool providing facility through all aspects of the groundwater flow and transport modeling process. Facilities include geometric modeling of hydrostratigraphy, two- and three-dimensional mesh generation, graphically based model input for specific flow and transport codes, …

Polynomial Real Root Finding In Bernstein Form, Melvin R. Spencer

Theses and Dissertations

This dissertation addresses the problem of approximating, in floating-point arithmetic, all real roots (simple, clustered, and multiple) over the unit interval of polynomials in Bernstein form with real coefficients.

A General Three Dimensional All Quadrilateral Surface Mesh Generation Algorithm, Roger Cass

Theses and Dissertations

Among the available all-quadrilateral mesh generation algorithms progressive-front offers the best quality and robustness. The paving algorithm is a progressive-front technique that generates a two dimensional mesh of all quadrilaterals on planar surfaces. The technique is particularly suited to meshing irregular boundaries with interior holes. This thesis presents an extension of the paving algorithm to generalized three dimensional surfaces. The major problems in three-dimensional surface mesh generation are projection of nodes, calculation of interior angles, and connection of mesh fronts. The solutions to these problems are presented. This work is part of the ongoing CUBIT project at Sandia Labs. The …

Automatic Meshing Of Free-Form Deformation Solids, Ssuta S. Hsu

Theses and Dissertations

Development of computer models and subsequent finite element analysis, are important aspects of modern engineering design. In this process, the geometry creation and finite element analysis software are well developed; however, the process of discretizing a geometry into a proper finite element model is time consuming and tedious. The work presented here uses the free-form deformation method to create smooth solid models, and invokes a solid subdivision and transition method to generate the hexahedron finite elements. The combination of these two techniques provides an automatic mesh generator that is easy to use, creates acceptable hexahedron elements for finite element analysis, …

Free-Form Deformations In A Constructive Solid Geometry Modeling System, Scott R. Parry

Theses and Dissertations

No one will question that computers are revolutionizing the design industry. It is pointed out in [Bezier84] that before CAD/CAM, a surface was defined by tracing cross sections on a drawing and then carving these sections in wood, plastic or metal. The final model was determined by someone interpolating between the sections. This labor intensive art is being replaced by techniques of computer aided geometric design.