Engineering Commons^™

Modeling Vibration Stiffness: An Analytical Extension Of Hertzian Theory For Angular Contact Bearings With A Thin Viscoelastic Coating, Davis R. Burton

Honors Theses

This thesis considers the novel angular contact rolling-element bearings proposed by NASA’s Glenn Research Center, which are coated with a thin solid lubricant that exhibits viscoelastic behavior. Current analytical models for the dynamic stiffness matrix of angular contact bearings, critical for vibration analysis, lack the ability to model the effects of a solid coating, as well as the time dependencies inherent in viscoelastic theory. The author first presents an overview of the stiffness matrix derivation, followed by a treatment of the underlying Hertzian contact theory. An analytical extension of this theory is proposed which accounts for a thin elastic layer …

Determining Thermal Properties Via Parameter Estimation Of A One-Dimensional, Analytical Model, Lauren B. Tomanek

Doctoral Dissertations

“In thermal applications, thermal conductivity is used to predict how well a material conducts heat. The accuracy of the magnitude of the thermal conductivity becomes increasingly essential to optimize part geometry. Thermal conductivity can vary significantly from the nominal value due to post-processing. The ASTM standards available to measure thermal conductivity are challenging to reproduce because of the insulated and prescribed temperature boundary conditions that are needed. The research introduces two new methods for estimating thermal conductivity that deliver the same accuracy as the existing ASTM standards and are easier to implement. The methods account for losses in the heating …

Mechanics Of The Solid-State Bonding Under Severe Thermomechanical Processes, Xue Wang

Doctoral Dissertations

Friction stir welding (FSW) has found increased applications in automotive and aerospace industries due to its advantages of solid-state bonding, no fusion and melting, and versatility in various working conditions and material combinations. The extent and quality of the solid-state bonding between workpieces in FSW is the ultimate outcome of their industrial applications. However, the relationship among processing parameters, material properties, and bonding extent and fidelity remains largely empirical, primarily because of the lack of the mechanistic understanding of (1) tool-workpiece frictional behavior, and (2) bonding formation and evolution.

In this dissertation, to study the underlying mechanism of tool-workpiece frictional …

The Development And Evaluation Of A New Analytical Model For The Characterization Of Friction Induced Disc Brake Vibration, Michael Vladimirov

Master's Theses

This research proposes a new method of modeling vibration of disc brake systems. This modeling method treats the brake pads of a disc braking system as lumped spring-mass-damper subsystems and the disc as a continuous bar. This modeling concept increases both the ease of analytical expression and the insight provided into the behavior of the real-world systems. This paper describes the analytical expression of this model and its implementation in Matlab. A parameter variation study yielded results that agree with existing research, which serves to validate the fundamental principles of this proposed modeling method.

A Forward Analytic Model Of Neutron Time-Of-Flight Signals With Single Elastic Scattering And Beamline Attenuation For Inferring Ion Temperatures From Maglif Experiments, Colin A. Weaver

Nuclear Engineering ETDs

A forward analytic model is required to rapidly simulate the neutron time-of-flight (nToF) signals that result from magnetized liner inertial fusion (MagLIF) experiments at Sandia’s Z Pulsed Power Facility. Various experimental parameters, such as the burn-weighted fuel-ion temperature and liner areal density, determine the shape of the nToF signal and are important for characterizing any given MagLIF experiment. Extracting these parameters from measured nToF signals requires an appropriate analytic model that includes the primary DD neutron peak, once-scattered neutrons in the beryllium liner of the MagLIF target, and direct beamline attenuation. Mathematical expressions for this model were derived from the …

Full-Scale Measurements To Evaluate Single-Ply Metal Roof Performance Under Extreme Wind Loads, Mahshid Nasiri

Electronic Thesis and Dissertation Repository

This study focused on assessing the performance of single-ply metal roofing system under high wind loads. Full-scale measurements were conducted at Insurance Research Lab for Better Homes at the University of Western Ontario, on a full-scale standing seam metal roof (SSMR) system in order to investigate the load sharing among the clip fasteners. A pressure loading approach was used for applying pressure distributions with spatial and time variation on the roof system as the induced loads on the clips were measured using installed load cells. The influence functions of clip reactions were measured. It was observed that the area of …

Volterra Series Approximation For Multi-Degree Of Freedom, Multi-Input, Multi-Output, Aircraft Dynamics, Alexander J. Chen

Mechanical & Aerospace Engineering Theses & Dissertations

An analytical model of a second order system is extended from a single-axis framework, to a multi-axis, multi-degree of freedom framework for a multiple input, multiple output system. This mathematical model is built from the variational approach of the Volterra series representation of nonlinear systems. The new representation describes the second order, oscillatory natural modes of a system, and shows how to organize the Volterra terms in intuitive ways. The constructed mathematical model aims to establish an organization of the Volterra kernels to allow for analytical cause and effect type analysis on system behavior.

To demonstrate the accuracy of the …

Development And Modeling Of A Biosensor Platform Using Algan/Gan Hemt Devices, Fahmida Shaheen Tulip

Doctoral Dissertations

The history of biosensors began in 1962 with the invention of enzyme electrodes by Leland C. Clark. Since then, biosensors have come a long way with simultaneous contributions in various fields such as biology, chemistry, material science, electronics, physics and VLSI. With the advancement in science and technology, smaller, more sensitive and dependable biosensors have become a reality. Still the need for cost-effective, sophisticated, reliable, robust biosensors that can be used to detect multiple types of biomolecules remains a technological challenge to be resolved.

The proposed AlGaN/GaN High Electron Mobility Transistors (HEMTs) have excellent prospect to become the biosensor platform …

In-Plane Lateral Load Capacities Of Vertically Oriented Interlocking Timber Panels, Brandon T. Decker

Theses and Dissertations

The Vertically Oriented Interlocking Timber (VOIT) panel is a new solid wood panel similar to Interlocking Cross Laminated Timber (ICLT) and the more commonly known Cross Laminated Timber (CLT). Like ICLT, VOIT panels use timber connections instead of the adhesives or metal fasteners common to CLT. The difference of VOIT is the orientation of the layers. Where CLT and ICLT panels alternate the orientation of each layer, VOIT panels orient all the layers in the same direction. The vertically oriented layers are then attached to one another by smaller horizontal dovetail members.Two types of VOIT panels were provided to be …

A Feasibility Study Of Multi-Functional Wells For Water Coning Control And Disposal, Lu Jin

LSU Doctoral Dissertations

Although water coning is well understood, it is difficult to control in field operations resulting in low recovery and large volumes of waste produced water. A solution - proposed here - is a multi-functional well with the in-situ bottom water drainage and injection installations - Downhole Water Loop (DWL). Theoretically, DWL greatly improves well performance (for example, a two-fold increase of DWL well’s water drainage rate would increase the critical (water-free) oil rate by 80%). However, DWL has practical limitations that must be quantified for actual well design. The objective of this work is to: (1) find maximum water drainage …

Structural Properties Of Iclt Wall Panels Composed Of Beetle Killed Wood, David Edward Wilson

Theses and Dissertations

Interlocking Cross Laminated Timber (ICLT) wall panels are a new wood construction product similar to Cross Laminated Timber panels. Besides being an innovative structural system, they also utilize beetle killed timber from many of the forests that have been devastated by the Mountain Pine Beetle. Three tests were performed on three ply ICLT panels measuring 8 feet (2.44m) wide, 8 feet (2.44m) tall and 8.5 inches (21.6cm) thick to determine the racking, flexural and axial strengths of the wall panels. After each test was performed the walls were disassembled and investigated for cause of failure. Using the data from the …

Probablistic Assessment Of Roof Uplift Capacities In Low-Rise Residential Construction, Bagyalakshmi Shanmugam

All Dissertations

Post hurricane damage investigations of light frame wood residential structures reveal that roof envelope failure induces considerable damage to the structure and its contents. Roof - to - wall (RTW) connection failures though not as common as roof sheathing failure also cause significant structural and material damage. Considerable changes have been made in the ASCE structural loads standard and International Building code (IBC) after hurricane Andrew in order to prevent RTW connection and sheathing failures. That includes not only a substantial increase in the design wind load in the past two decades but also a strict enforcement of tighter nailing …

Analytical And Numerical Investigation Of A Mechanically Stabilized Earth Wall On I-15, Aaron S. Budge

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation is the culmination of extensive research into the behavior of a mechanically stabilized earth (MSE) wall at I-15 and 3600 South in Salt Lake City, Utah. The wall is about 30 ft tall and is constructed on a compressible, soft clay foundation. Research on this project has included extensive instrumentation and monitoring of stresses and deformations in the wall and its foundation, a study of the effects of drilling and sampling method on disturbance of samples, and extensive laboratory testing to determine strength and deformation properties of soils at the site. The results of these portions of the …