Engineering Commons^™

Spline-Based Contact: Algorithms And Applications, Pulama Bhattacharya

Theses and Dissertations

Contact is one of the most challenging nonlinearities to solve in solid mechanics. In traditional linear finite element analysis, the contact surface is only C^0 continuous, as a result, the normal to the contact surface is not continuous. The normal contact force is directed along the normal in the direction of the contact surface, and therefore, the contact force is discontinuous. This issue is tackled in linear finite element analysis using various surface smoothing techniques, however, a better solution is to use isogeometric analysis where the solution space is spanned by smooth spline basis functions. Unfortunately, spline-based isogeometric contact analysis …

Modeling The Effects Of Parameter Changes On Heating And Pressure At The Weld Interface And Joint Strength In Friction Bit Joining, Adam Hartly Wagner

Theses and Dissertations

Joining of dissimilar metals is a process that is of interest in many fields, especially the automotive industry where lightweighting of the body structure is important. However, creating strong joints between dissimilar metals can be challenging. Friction bit joining (FBJ) is a solid-state method that uses a consumable bit to create a strong joint between dissimilar metals such as aluminum and steel. The purpose of this research is to gain understanding of how adjusting FBJ parameters affects the heating and pressure at the weld interface using a modeling approach, in order to better understand the bonding process. The questions guiding …

The Impact Of Inkjet Parameters And Environmental Conditions In Binder Jetting Additive Manufacturing, Trenton Miles Colton

Theses and Dissertations

Binder jetting is an additive manufacturing process in which a part is fabricated layer-by-layer using inkjet technology to selectively dispense binder into powder layers in a designated area. The approach gives this process significant advantages over other additive manufacturing processes such as lower cost, capability to print in a wide range of materials, and little to no heat applied. Although binder jetting has many advantages and has been successful implemented in various industries its overall rate of adoption is slow compared to other processes. This is largely due to poor mechanical properties and consistency in printing which stems from a …

A Study Of The Effect Of Load And Displacement Control Strategies On Joint Strength In Friction Bit Joining Of Ga Dp 1180 Steel And Aa 7085-T71, Taylor George Berg

Theses and Dissertations

Friction Bit Joining (FBJ) is a new technology that can be used to join dissimilar materials together. This ability makes it a good candidate for creating lightweight structures for the automotive industry by combining lightweight materials such as aluminum to stronger materials like advanced high-strength steels. The automotive industry is putting significant effort into interest in reducing vehicle structure weight to increase fuel efficiency and reduce greenhouse gas emissions. Joining of dissimilar materials is a challenge they face in the light weighting the body of the vehicle. The purpose of the current research is to employ FBJ in the joining …

Development And Evaluation Of An Improved Microbial Inactivation Model For Analyzing Continuous Flow Uv-Led Air Treatment Systems, Cole Holtom Thatcher

Theses and Dissertations

This thesis discusses the development of an improved microbial inactivation model for analyzing continuous flow UV-LED air treatment systems and use of the model to evaluate the impact of several treatment system design parameters on inactivation. Model development includes three submodels: a radiation submodel, a fluid flow submodel, and an inactivation kinetics submodel. Radiation modeling defines the UV irradiance throughout the system. Fluid flow modeling provides the residence times that microbes spend exposed to the UV irradiation while passing through the system. Inactivation modeling combines irradiance and residence times with inactivation kinetics to calculate species-specific inactivation in a treatment system. …

Method For Creating Subject-Specific Models Of The Wrist In Both Degrees Of Freedom Using Measured Muscle Excitations And Joint Torques, Blake Robert Harper

Theses and Dissertations

Two-thirds of repetitive strain injuries affect the wrist joint. Although force is believed to be one of the major factors, the forces involved in wrist movements have not been thoroughly characterized in vivo. Computer simulations with a musculoskeletal model of the wrist have been used to estimate wrist muscle forces, but only at maximum voluntary contraction and only involving a single degree of freedom (DOF). In this study we present a method for creating a subject-specific model that can be used to estimate muscle forces and joint torques in both degrees of freedom of the wrist over a range of …

3d Permeability Characterization Of Sheared Fiber Reinforcement For Liquid Composite Molding Process Simulation, Collin William Childs

Theses and Dissertations

Resin transfer molding (RTM) is an infusion-based closed-mold manufacturing process where resin is injected into a preform of dry reinforcement to create a net shape part. Often, when a preform is draped over a mold with complex geometry, such as the double curvature of a dome, a reorientation of the fibers takes place in the form of in-plane shear. This deformation of the reinforcement structure has the potential to adversely affect the resin flow and the filling of the mold during RTM if the manufacturer fails to properly account for the shear effects. Various process simulation tools are being developed …

Partial Circuit Replication For Masking And Detecting Soft Errors In Sram-Based Fpgas, Andrew Mark Keller

Theses and Dissertations

Partial circuit replication is a soft error mitigation technique that uses redundant copies of a circuit to mask or detect the effects of soft errors. By masking or detecting the effect of soft errors on SRAM-based FPGAs, implemented circuits can be made more reliable. The technique is applied selectively, to only a portion of the components within a circuit. Partial application lowers the cost of implementation. The objective of partial circuit replication is to provide maximal benefit at limited or minimized cost. The greatest challenge of partial circuit replication is selecting which components within a circuit to replicate. This dissertation …

Thermal Transport To Impinging Droplets On Superhydrophobic Surfaces, Jonathan C. Burnett

Theses and Dissertations

An analytical model is developed to quantify the heat transfer to droplets impinging on heated superhydrophobic (SH) surfaces. Integral analysis is used to incorporate an apparent temperature jump at the superhydrophobic surface as a boundary condition. This Thesis considers the scenario of both isotropic and anisotropic slip, as would be realized on post-cavity style and rib-cavity style SH surfaces. This thermal model is combined with a hydrodynamic model which incorporates velocity slip at the surface. Use of the two models allows determination of the overall cooling effectiveness, a metric outlined in contemporary work. The effect of varying velocity slip and …

Sensitivity Of Tremor Propagation To Model Parameters, Charles Paul Curtis Jr.

Theses and Dissertations

Although Essential Tremor (ET) is the most common type of tremor, many patients are left without satisfactory treatment options. One potential alternative treatment to medication or surgery is a wearable tremor-suppressing device. However, optimizing the effectiveness of such a device requires knowledge of which muscles/joints are most responsible for tremor. To answer this question, current efforts simulate tremor propagation using a model of the neuromusculoskeletal dynamics of the upper limb. To guide efforts to identify realistic model parameters and use the model to determine the mechanical origin of tremor, we performed preliminary parameter estimation work and a thorough sensitivity analysis …

Cedar: A Dimensionally Adaptive Flow Solver For Cylindrical Combustors, Ty R. Hosler

Theses and Dissertations

This thesis discusses the application, evaluation, and extension of dimensionally adaptive meshing to the numerical solution of velocity and pressure fields inside cylindrical reactors. Due to the high length to diameter ratios of many cylindrical reactor vessels the flow field can become axisymmetric, allowing for simplification of the governing equations and significant reduction in computational time required for solution. A fully 3D solver is developed from existing computational tools at BYU and validated against theoretical velocity profiles for pipe flow at various Reynolds numbers, as well as with experimental data for an axial-fired center jet with recirculating flow. Dimensionally adaptive …

Resiliency Of Utah's Road Network: A Logit-Based Approach, Max Evan Barnes

Theses and Dissertations

The Utah Department of Transportation (UDOT) manages and maintains a complex state-wide network of highways. Recent incidents such as the collapse of the I-35W bridge in Min- neapolis, Minnesota, and the I-85/Piedmont Road fire and subsequent bridge collapse in Atlanta, Georgia, have brought identification of transportation network vulnerabilities to the forefront of UDOT’s planning efforts. Traditional estimates of transportation network impacts have focused on increases to user travel time or the volume of affected traffic, but studies of these disasters have revealed that when facing a degraded transportation network, people adjust their trip making in terms of destination, mode, and …

Semiflexible Oligomers Crystallize Via A Cooperative Phase Transition, Pierre Kawak, Dakota S. Banks, Douglas R. Tree

Faculty Publications

Semicrystalline polymers are ubiquitous, yet despite their fundamental and industrial importance, the theory of homogeneous nucleation from a melt remains a subject of debate. A key component of the controversy is that polymer crystallization is a non-equilibrium process, making it difficult to distinguish between effects that are purely kinetic and those that arise from the underlying thermodynamics. Due to computational cost constraints, simulations of polymer crystallization typically employ non-equilibrium molecular dynamics techniques with large degrees of undercooling that further exacerbate the coupling between thermodynamics and kinetics. In a departure from this approach, in this study, we isolate the near-equilibrium nucleation …

Stochastic Modeling Of Surface Scalar-Flux Fluctuations In Turbulent Channel Flow Using One-Dimensional Turbulence, Marten Klein, Heiko Schmidt, David O. Lignell

Faculty Publications

Accurate and economical modeling of near-surface transport processes is a standing challenge for various engineering and atmospheric boundary-layer flows. In this paper, we address this challenge by utilizing an economical stochastic one-dimensional turbulence (ODT) model. ODT aims to resolve all relevant scales of a turbulent flow for a one-dimensional domain. Here ODT is applied to turbulent channel flow as stand-alone tool. The ODT domain is a wall-normal line that is aligned with the mean shear. The free model parameters are calibrated once for the turbulent velocity boundary layer at a fixed Reynolds number. After that, we use ODT to investigate …

System Identification Of Postural Tremor In Wrist Flexion-Extension And Radial-Ulnar Deviation, Sydney Bryanna Ward

Theses and Dissertations

Generic simulations of tremor propagation through the upper limb have been achieved using a previously developed postural tremor model, but this model had not yet been compared with experimental data or utilized for subject-specific studies. This work addressed these two issues, which are important for optimizing peripheral tremor suppression techniques. For tractability, we focused on a subsystem of the upper limb: the isolated wrist, including the four prime wrist muscles (extensor carpi ulnaris, flexor carpi ulnaris, extensor carpi radialis, and flexor carpi radialis) and the two degrees of freedom of the wrist (flexion-extension and radial-ulnar deviation). Muscle excitation and joint …

Constrained Nonlinear Heuristic-Based Mpc For Control Of Robotic Systems With Uncertainty, Tyler James Quackenbush

Theses and Dissertations

This thesis focuses on the development and extension of nonlinear evolutionary model predictive control (NEMPC), a control algorithm previously developed by Phil Hyatt of the BYU RaD Lab. While this controller and its variants are applicable to any high degree-of-freedom (DoF) robotic system, particular emphasis is given in this thesis to control of a soft robot continuum joint. First, speed improvements are presented for NEMPC. Second, a Python package is presented as a companion to NEMPC, as a method of establishing a common interface for dynamic simulators and approximating each system by a deep neural network (DNN). Third, a method …

Statistical Method For Extracting Radiation-Induced Multi-Cell Upsets And Anomalies In Sram-Based Fpgas, Juan Andres Perez Celis

Theses and Dissertations

FPGAs are susceptible to radiation-induced effects that change the data in the configuration memory. These effects can cause the malfunction of the system. Triple modular redundancy has extensively been used to improve the circuit's cross-section. However, TMR has shown to be particularly susceptible to radiation effects that affect more than one memory cell such as Multiple Cell Upsets (MCU) or micro-Single Event Functional Interrupts (micro-SEFI). This work describes a statistical technique to extract Multi-Cell Upset (MCU) and micro-SEFI events from raw radiation upset data. The technique uses Poisson statistics to identify patterns in the data. The most common patterns are …

Completion And Initial Testing Of A Pressurized Oxy-Coal Reactor, Scott Hunsaker Gardner

Theses and Dissertations

Oxy-combustion is a process which removes nitrogen from air prior to combustion in order to produce a high concentration of CO2 in the exhaust. This enables CO2 liquefaction, transport, and storage to greatly reduce CO2 emissions to the atmosphere. Atmospheric oxy-coal combustion has been successfully demonstrated at industrial scales and could be retrofit in existing coal boilers, but thermodynamic efficiencies are low and therefore uneconomical. Pressurized oxy-coal combustion has the potential for higher efficiency and lower cost but requires new technologies related to the coal feed system, the burner, and ash management. This project describes work needed to complete the …

A Study In Soft Robotics: Metrics, Models, Control, And Estimation, Levi Thomas Rupert

Theses and Dissertations

Traditional robots, while capable of being efficient and effective for the task they were designed, are dangerous when operating in unmodeled environments or around humans. The field of soft robotics attempts to increase the safety of robots thus enabling them to operate in environments where traditional robots should not operate. Because of this, soft robots were developed with different goals in mind than traditional robots and as such the traditional metrics used to evaluate standard robots are not effective for evaluating soft robots. New metrics need to be developed for soft robots so that effective comparison and evaluations can be …

Large-Scale Reality Modeling Of A University Campus Using Combined Uav And Terrestrial Photogrammetry For Historical Preservation And Practical Use, Bryce Berrett, Cory Vernon, Haley Beckstrand, Madi Pollei, Kaleb Markert, Kevin Franke, John Hedengren

Faculty Publications

Unmanned aerial vehicles (UAV) enable detailed historical preservation of large-scale infrastructure and contribute to cultural heritage preservation, improved maintenance, public relations, and development planning. Aerial and terrestrial photo data coupled with high accuracy GPS create hyper-realistic mesh and texture models, high resolution point clouds, orthophotos, and digital elevation models (DEMs) that preserve a snapshot of history. A case study is presented of the development of a hyper-realistic 3D model that spans the complex 1.7 km2 area of the Brigham Young University campus in Provo, Utah, USA and includes over 75 significant structures. The model leverages photos obtained during the historic …

Space-Time Coded Artm Cpm For Aeronautical Mobile Telemetry, Chad Carl Josephson

Theses and Dissertations

This dissertation explores the application of Silvester's space-time block code to the multi-index CPM called "ARTM CPM" in the IRIG 106 standard to solve the "two antenna problem"---the use of two transmit antennas to provide full spatial coverage on an airborne test article and the accompanying self interference due to different delays between the two transmit antennas and the ground-based receive antenna. A symbol-level encoding scheme is derived that allows the burst-based space-time block code to operate in a continuously streaming mode. The results show that the space-time block code can solve the two antenna problem with differential delays, but …

Extending Multi-Beam Sonar With Structure From Motion Data Of Shorelines For Complete Pool Bathymetry Of Reservoirs, Izaak Brandt Cooper

Theses and Dissertations

Bathymetric mapping is an important tool for reservoir management, typically completed before reservoir construction. Historically, bathymetric maps were produced by interpolating between points measured at a relatively large spacing throughout a reservoir, typically on the order of a few, up to 10, meters or more depending on the size of the reservoir. These measurements were made using traditional survey methods before the reservoir was filled, or using sonar surveys after filling. Post-construction issues such as sedimentation and erosion can change a reservoir, but generating updated bathymetric maps is difficult as the areas of interest are typically in the sediment deltas …

Fourier Analysis And Other Tools For Electrical Engineers: A Practical Handbook, David G. Long

Books

No abstract provided.

A High-Pressure Shear Testing Approach To Measure Flow Stresses Near A Friction Stir Welding Tool, David Prymak, Michael Miles, Tracy W. Nelson, Fredrick Michael

Faculty Publications

A new approach for measuring flow stresses near a spinning friction stir welding (FSW) tool is evaluated on AA 6061-T6 plate. The test consists of plunging a cylindrical tool with a flat face into the plate at different rotational speeds, using a variety of constant vertical loads. A viscosity-based model of the shear layer created under the tool is employed to estimate local flow stresses. The flow stresses measured by this approach exhibited an inverse relationship with temperature and a positive dependence on the pressure imposed by the spinning flat-faced tool. Compared to hot compression and hot torsion results, estimated …

Correlation Of Segmental Lumbar Kinematics With A Wearable Skin Strain Sensor Array, Andrew Gibbons, Paul Mcmullin, Joseph Peterson, Spencer Baker, Kelly Clingo, Ulrike H. Mitchell, David T. Fullwood, Anton E. Bowden

Student Works

Introduction: Joint kinematics have been shown to be strongly diagnostic of underlying pathology in the knee, hip, shoulder, and ankle. However, the anatomical complexity of the spine has made obtaining accurate, segmental kinematics extremely challenging. Current approaches required specialized hardware (e.g., a dual x-ray system), or are highly invasive (e.g., bone pins implanted into the vertebrae). Recently, our lab has developed a wearable array of skin-mounted strain sensors that hopes to address this challenge. The purpose of the present work study was to quantify the utility of this array through comparison with real-time lumbar vertebral kinematics.

Materials and Methods: A …

Towards Detection Of Sars-Cov-2 Rna In Human Saliva: A Paper-Based Cell-Free Toehold Switch Biosensor With A Visual Bioluminescent Output, J. Porter Hunt, Emily Long Zhao, Tyler J. Free, Mehran Soltani, Chandler A. Warr, Alex B. Benedict, Melissa K. Takahashi, Joel S. Griffitts, William G. Pitt, Bradley C. Bundy

Faculty Publications

The COVID-19 pandemic has illustrated the global demand for rapid, low-cost, widely distributable and point-of-care nucleic acid diagnostic technologies. Such technologies could help disrupt transmission, sustain economies and preserve health and lives during widespread infection. In contrast, conventional nucleic acid diagnostic procedures require trained personnel, complex laboratories, expensive equipment, and protracted processing times. In this work, lyophilized cell-free protein synthesis (CFPS) and toehold switch riboregulators are employed to develop a promising paper-based nucleic acid diagnostic platform activated simply by the addition of saliva. First, to facilitate distribution and deployment, an economical paper support matrix is identified and a mass-producible test …

Development Of An Origami Inspired Composite Deployable Structure Utilizing Compliant Joints As Surrogate Folds, Samuel Porter Smith

Theses and Dissertations

This work presents the design and construction of a self-deployable, self-stiffening,and retractable (SDSR) space array from carbon fiber reinforced polymers (CFRP’s) and a working prototype is demonstrated. The effort required developing principles for the design of high-strain composite flexural joints and their integration into angled composite panels. Designing LET arrays in angled panels is explored. Analysis of simple composite LET joints is presented for two degrees of freedom. Validation of the composite LET modeling is sought through numerical methods and empirical testing. Testing of several composite LET joint specimens is conducted and the results are reported. Results indicate that (while …

Characterizing Behaviors And Functions Of Joints For Design Of Origami-Based Mechanical Systems, Nathan Chandler Brown

Theses and Dissertations

This thesis addresses a number of challenges designers face when designing deployable origami-based arrays, specifically joint selection, design, and placement within an array. In deployable systems, the selection and arrangement of joint types is key to how the system functions. The kinematics and performance of an array is directly affected by joint performance. This work develops joint metrics which are then used to compare joint performances, constructing a tool designers can use when selecting joints for an origami array. While often a single type of joint is used throughout an array, this work shows how using multiple types of joints …

Dynamic Simulation Of A Novel Nuclear Hybrid Energy System With Large-Scale Hydrogen Storage In An Underground Salt Cavern, An Ho, Kasra Mohammadi, Matthew Memmott, John Hedengren, Kody Powell

Faculty Publications

In this study, a nuclear hybrid energy system (NHES) with large-scale hydrogen storage integrated with a gas turbine cycle is proposed as a flexible system for load following. The proposed system consists of a nuclear reactor, a steam Rankine cycle, a hydrogen electrolyzer, a storage system for hydrogen in an underground salt cavern, and a Brayton cycle that uses hydrogen as fuel to generate additional electricity to meet peak demand. A dynamic mathematical model is developed for each subsystem of the NHES. To evaluate the potential benefits of the system, a one-year study is conducted, using scaled grid demand data …

Acclimation Of Contact Impedance And Wrist-Based Pulsatile Signal Measurements Through Electrical Bioimpedance, Diego A. Leon

Theses and Dissertations

The purpose of this research is to expand the understanding of certain properties of electrodes used for electrical bioimpedance measurements. Specifically, this work investigates the acclimation effect of the skin-electrode interface contact impedance. It also attempts to study the relationship between electrode spacing and amplitude of bioimpedance pulsatile signals. It was found that as soon as dry electrodes are placed on the skin, the contact impedance exponentially decreases until it reaches a constant level. The acclimation time, time to reach a constant contact impedance, is dependent of the electrode size and frequency. Increasing the size of the electrode, as well …