Mechanical Engineering Commons^™

Design And Development Of Magnetoelastic Resonators For Pv Ground Fault Detection, Skyler H. Oglesby

Mechanical Engineering ETDs

This project will design, fabricate, and test a magnetoelastic nickel-iron-cobalt alloy resonator for ground fault detection applications, specifically in photovoltaic systems. The electrodeposition technique will be used to fabricate the proposed resonator as it enables a precise manufacturing process. It allows for better control and optimization of material properties (magnetic, mechanical, and electrical) while facilitating the necessary dimensions. A great deal of study and experimentation will go into the electrolyte development when dealing with challenges like intrinsic stress and surface defects within the film. Hull cell analysis will be done to study the composition of the material in different electrochemical …

Mechanical Characterization Of Additively Manufactured Alloys Compared To Their Wrought Counterparts, Laith A. Alqawasmi

Mechanical Engineering ETDs

Additive manufacturing is a method of manufacturing based on building parts layer by layer, allowing for more control over shape of the product, therefore reducing machining costs, reducing material waste, faster production times and the ability to build complex engineering design that other manufacturing technologies won’t be able to produce. This research is on the tensile and indentation testing (following ASME standards) of 3D printed Ti-6Al-4V and Inconel 718 built by powder-based direct energy deposition technology. Ti-6Al-4V is an attractive material for the aerospace and aviation industry, and Inconel 718, a nickel-chromium based superalloy, is an attractive material for usage …

Development Of Models For The Velocity-Pressure Gradient Correlations In Incompressible Wall-Bounded Planar Turbulent Flows Using Multiple Linear Regression, Juampablo E. Heras Rivera

Mechanical Engineering ETDs

In this thesis, the multiple linear regression method is applied to clarify terms and their coefficients in data-driven models for velocity/pressure-gradient (VPG) correlations in the Reynolds stress transport equations. Additionally, a method for developing universal linear models for the VPG correlations with unchanging coefficients when complex conditions arise in a flow is introduced. The generated models were assessed using residual analysis to ensure an appropriate level of accuracy. Data from direct numerical simulation in an incompressible fully-developed turbulent channel flow at Re_tau = 392 with an adverse pressure gradient is used in the study as the data source.

On The Effects Of Geometrical And Fluid Conditions On Thermal-Hydraulics Of Miniature Heat Sinks, Mahyar Pourghasemi

Mechanical Engineering ETDs

During the past three years, miniature heat sinks have been integrated into the cooling loop of devices such as MW-class gyrotron resonators and high-power laser arrays. These applications involve high cooling rates in the range of 20-25 MW/m². Liquid metals such as Na and NaK offer very high thermal conductivity in the range of 16-79 W/mK, while their dynamic viscosities are only slightly higher than water viscosity. They can also be used in applications with operating temperatures varying from 25 ^oC to as high as 800 ^oC due to their very high boiling points. Several research …

Cyber-Secure Distributed Control Of Microgrids With Improved Communication And Control Protocols, Jee Won Choi

Mechanical Engineering ETDs

This dissertation proposes a cyber-secure distributed control of microgrids with improved communication and control protocols. The finite-time event-triggered control protocol for islanded AC and DC secondary control is introduced. For AC microgrids, the proposed strategy can effectively perform frequency restoration and voltage regulations while sharing the active and reactive power among the distributed generators (DGs) based on their power ratings. For DC microgrids, the proposed control protocol can provide accurate current sharing and critical bus voltage regulation. The finite-time control enables a system to reach a consensus in a finite period of time enhanced from asymptotic convergence. The event-triggered communication …

Particle Image Velocimetry Methodology For Calculating The Advective Losses At The Solar Tower For The Gen 3 Concentrated Solar Power System, Guillermo Anaya

Mechanical Engineering ETDs

The Falling Particle Receiver (FPR) built by Sandia National Laboratory (SNL) at the National Solar Thermal Testing Facilities (NSTTF) is one of the latest concentrated energy harvesting systems for Concentrated Solar Power (CSP). The FPR system at the NSTTF uses solid particles as both the heat transfer fluid and storage media. This FPR operates by having a gravity-driven particles curtain being irradiated through an open cavity by CSP, provided by a heliostat field. However, during operation plumes of particles being expelled out of the receiver cavity can be observed, resulting in heat losses as well as particle inventory losses. The …

Evolution Of Shock-Driven Multi-Phase Instability, Joshua Chavez

Mechanical Engineering ETDs

ABSTRACT

In many models and experiments using shock tubes and shock tube instabilities, measurements of velocity and position of the flow features are frequently taken in a single horizontal direction (or in one plane), however, the three-dimensional flow structure is important and cannot be fully resolved by such measurements. By placing a mirror at 45 degrees atop a test section of a shock tube, it becomes possible to visualize the flow from two directions simultaneously. The mirror is used to see if viable data can be gathered from the second view in conjunction with the main view. With high-speed video …

Material Characterization And Comparison Of Sol-Gel Deposited And Rf Magnetron Deposited Lead Zirconate Titanate Thin Films, Katherine Lynne Miles

Mechanical Engineering ETDs

Lead zirconate titanate (PZT) has been a material of interest for sensor, actuator, and transducer applications in microelectromechanical systems (MEMS). This is due to their favorable piezoelectric, pyroelectric and ferroelectric properties. While various methods are available to deposit PZT thin films, radio frequency (RF) magnetron sputtering was selected to provide high quality PZT films with the added capability of batch processing. These sputter deposited PZT films were characterized to determine their internal film stress, Young’s modulus, composition, and structure. After characterization, the sputtered PZT samples were poled using corona poling and direct poling methods. As a means of comparison, commercially …

Simulation Of Supercritical Multiphase Flows Using Machine Learning, Nelson P. Longmire

Mechanical Engineering ETDs

In many technologies, such as rocket engines and modern power plants, the pressures of the fluids in these systems have increased to increase efficiency. As a result, the fluids are under pressures higher than the critical pressure meaning the fluids are supercritical. Supercritical fluids are unique as a liquid/gas phase equilibrium no longer exists, and a process called pseudo boiling occurs where the fluid properties have steep gradients, which lead to interesting fluid mechanics and heat transfer characteristics. Our understanding of supercritical fluids has had exciting advances over the years. However, there are still phenomena that are still not well …

Design, Microfabrication And Characterization Of Vibrating Mesh Atomizer For Viscous Fluids, Pallavi Sharma

Mechanical Engineering ETDs

This research focuses on a new piezoelectrically driven Micro Electromechanical Systems based vibrating mesh atomizer that generates the pressure differential required for droplet ejection or spray production using frequency resonances in the 100 kHz range. This study involves device construction and experimental characterization to comprehend the device's operation and the influence of various factors on its performance and determine the limitations of a range of working fluids to atomize.

A novel approach to integrating polymer-based micro heaters with a vibrating mesh atomizer as a monolithic component is presented to expand the range of working liquids for the MEMS device. The …

Augmented Reality For Human Control Of Engineering Tasks, Elijah Wyckoff

Mechanical Engineering ETDs

This research is motived by the study of dynamics, especially in experimentation and Structural Health Monitoring (SHM) methods. It is important that inspectors maintain awareness of test structures while observing sensor data and inputting control. Humans receive a large amount of information from vision, and this feedback is crucial to inform decision making. Human-computer interaction (HCI) provides valuable data and information but separates the human from reality as it is necessary to look away from the region of interest to view information on a separate device. Additionally, sensor data does not collect experiment safety, quality, and other contextual information of …

Run-To-Run Control Via Constrained Optimization Of A Mechanical Serial-Sectioning System, Damian L. Gallegos-Patterson

Mechanical Engineering ETDs

This thesis develops a methodology for run-to-run (R2R) control of a mechanical serial sectioning (mss) system for microstructural investigations. mss is a destructive material characterization process which repeatedly removes a thin layer of material and images the exposed surface. The images are then used to gain insight into the internal structure and arrangement of a material and are often used to generate a 3-dimensional (3D) reconstruction of the sample. Currently, an experienced human operator selects the parameters for mss to achieve the desired per slice removal rate. The proposed R2R control methodology automates this process while improving the precision and …

Expanded-Range Venturi Flow Meter: Development And Testing Of A 3d-Printed Flow Meter And Solid-State Valve Concept, Joseph M. Pomo

Mechanical Engineering ETDs

In this thesis, I document the design, testing and performance of a novel Expanded-Range Venturi Flow Meter (ERVFM) concept. The ERVFM combines two, parallel-configured Venturi Flow Meters (VFM) with a Solid-State Selector Valve (SSSV). The goal was to create a reliable, high-turndown ratio flow meter which directs the fluid to either Venturi tube using the inherent pressure drop of the SSSV, and without moving parts. I constructed a pumped-fluid loop test-setup and quantified the ERVFM’s performance through pressure loss and mass flow rate measurements. In addition, I used python to develop models to assist in prototype design and data-processing. My …

Fiesta And Shock-Driven Flows, Brian E. Romero

Mechanical Engineering ETDs

In this study, the interaction of a shock with various gas and particle interfaces is analyzed through simulations using a new, GPU capable, multi-species flow solver, FIESTA (Fast, Interface Evolution, Shocks, and Transport in the Atmosphere), de- veloped for this research. The cases studied include the interaction between a shock and i) a two-dimensional (2D), circular cloud of a dense gas; ii) a 2D curtain of a dense gas; iii) a three-dimensional (3D) cylinder of a dense gas, and iv) a 3D curtain of solid particles.

In simulations of a 2D gas curtain and a 3D gas column, the curtain …

Artificial Intelligence, Controls, And Sensor Fusion For Optimization And Modeling Of Space Missions And Particle Accelerators, Reza Pirayeshshirazinezhad

Mechanical Engineering ETDs

This PhD dissertation is devoted to developing artificial intelligence (AI) applications for space missions and particle accelerators considering constraints on the computational resources. The space mission studied in this research, the Virtual Telescope for X-ray Observations (VTXO), is the mission exploiting 2 6U-CubeSats operating in a precision formation. The goal of the VTXO project is to develop a space-based, X-ray imaging telescope with high angular resolution precision. VTXO space mission is designed and the mission is optimized to increase the performance of the mission. Trajectory optimization with AI, hybrid control, control algorithms, and high performance computing are all used to …

Multi-Scale Modeling Of Dislocation Motion And Interaction: Theory, Plastic Properties, And Boundary Conditions, Abu Bakar Siddique

Mechanical Engineering ETDs

Dislocation theory is the fundamental tool for explaining plasticity in the material. The elastic field of a material is always influenced by the presence of dislocations and other defects independent of the loading configurations. Scientists and researchers have minimal success in solving plasticity problems analytically. And for this reason, the capturing of dislocation dynamics is highly dependent on numerical modeling, which is always a challenge for its inherent multi-scale nature. Current research investigates and develops self-consistent numerical models for different plasticity problems based on the distributed-dislocation technique and the collocation-point method. Numerical methods are developed for different boundary conditions in …

Understanding Processing And Mechanics Of Extrusion-Based Additive Manufacturing For Multi-Material Parts, Jafar N/A Ghorbani

Mechanical Engineering ETDs

Despite the design freedom that additive manufacturing (AM) processes provide, there are still challenges in using some AM processes for end-use products. Fused filament fabrication (FFF), also known as material extrusion, is one of the AM technologies that has been used mainly for prototyping due to the low cost of machines, raw material, and ease of operation. Another advantage of FFF is its ease of integration with other additive or subtractive technologies. However, some disadvantages such as relatively poor and anisotropic mechanical properties have hindered FFF for end-use engineering components. The first chapter of this dissertation is a brief review …

A Novel Imaging Methodology To Estimate Advective Losses From A Concentrating Solar Power Particle Receiver, Jesus Daniel Ortega

Mechanical Engineering ETDs

Falling particle receivers (FPRs) such as the one at Sandia National Labs, represent the state-of-the-art Concentrating Solar Power (CSP) technology for energy harvesting. The FPR operates by creating a gravity-driven particle curtain in a receiver that is irradiated by concentrated sunlight from a field of concentrators. The particles are used directly as the heat transfer and storage media for the concentrated energy absorbed. However, during operation, particles can egress through the open aperture of the receiver cavity, resulting in particle-inventory and heat losses from the system. The particle plumes egressing from the cavity present a unique challenge to metrology due …

Dc Microgrid Fault Detection Using Multiresolution Analysis Of Traveling Waves, Rudy Montoya

Mechanical Engineering ETDs

Fast detection and isolation of faults in a DC microgrid is of particular importance. Fast tripping protection (i) increases the lifetime of power electronics (PE) switches by avoiding high fault current magnitudes and (ii) enhances the controllability of PE converters. This thesis proposes a traveling wave (TW) based scheme for fast tripping protection of DC microgrids. The proposed scheme utilizes a discrete wavelet transform (DWT) to calculate the high-frequency components of DC fault currents. Multiresolution analysis (MRA) using DWT is utilized to detect TW components for different frequency ranges. The Parseval energy calculated from the MRA coefficients are then used …

Dc Microgrid Fault Detection Using Multiresolution Analysis Of Traveling Waves, Rudy Montoya

Mechanical Engineering ETDs

Fast detection and isolation of faults in a DC microgrid is of particular importance. Fast tripping protection (i) increases the lifetime of power electronics (PE) switches by avoiding high fault current magnitudes and (ii) enhances the controllability of PE converters. This thesis proposes a traveling wave (TW) based scheme for fast tripping protection of DC microgrids. The proposed scheme utilizes a discrete wavelet transform (DWT) to calculate the high-frequency components of DC fault currents. Multiresolution analysis (MRA) using DWT is utilized to detect TW components for different frequency ranges. The Parseval energy calculated from the MRA coefficients are then used …

Zero-Power Ac Current Sensor, Omar Aragonez

Mechanical Engineering ETDs

In this study, a magnetic piezoelectric cantilever powered AC current and frequency sensor is proposed. This paper covers the configuration of the experimental setup, finite element modeling of the magnetic coupling, and the optimal spatial location of the magnetic proof mass in relation to the wire for smart grid applications. Solid and stranded copper wires of various gauges were used and carried current up to 30A. The magnets act as a proof mass to lower the frequency while also coupling to the magnetic field generated by the current carrying wire. The frequency of the AC current produces a sinusoidal force …

Method Of Embedded Imperfections For The Direct Simulation Of Deformation Instabilities In Film-Substrate Structures, Siavash Nikravesh Kazeroni

Mechanical Engineering ETDs

In this dissertation, a novel finite-element methodology called “embedded imperfections” is proposed and employed for computationally simulating various types of deformation instabilities observed in film-substrate structures subjected to mechanical loading. The approach involves the incorporation of elements having distinctive material properties within the film-substrate interface. One can interpret this practice as a deliberate distribution of material defects within the numerical model. It has been shown that embedded imperfections not only can trigger the onset of instability, but also can lead to “direct” simulation of deformation instability problems in that primary and subsequent instability modes can all be captured in a …

Incorporating In-Situ Monitoring To Detect Anomalies In Additively Manufactured Kovar Steel On A Layer-To-Layer Basis, Matthew Aragon

Mechanical Engineering ETDs

Combining traditional methods of material analysis with in-situ monitoring of a Laser Powder Bed Fusion (LPBF) printed part, on a layer-to-layer basis, provides the data necessary to adjust printing parameters to achieve specific material properties. Additively manufactured technology has advanced in the ability to accommodate new materials and provide new use cases. Uncertainties in material properties have arisen alongside the advancements in additive manufacturing. The layer-wise print analysis will allow for detection and correlation of print anomalies to the material properties such as density, material strength, and surface roughness. The data processed from each layer will be used to further …

Three-Dimensional Lattices As Effective Impact Absorption Layers For Space Applications, James Youchison

Mechanical Engineering ETDs

Additive manufacturing (AM) is increasingly becoming a viable manufacturing process due to dramatic advantages that it facilitates in the material selection and design complexity. This paper investigates the potential of additively manufactured lattice structures for the application of dissipating impact energy. In this research the role of geometry and material properties on the static and dynamic energy absorption properties of additively manufactured wave spring lattices composed of various materials were studied under drop/impact and compression tests. A finite element simulation of the lattice structure was also conducted, although the results were overall inconclusive, it gave some great insight into the …

Interaction Of A Shock Wave With A Particle Curtain, Daniel M. Freelong

Mechanical Engineering ETDs

This thesis presents an experimental study of the interaction of a normal shock wave with a sparse curtain of particles. Soda lime particles with a nominal diameter of 40 micrometers are used to form the curtain. A high speed camera captured several segments of the particle curtain flow from the front view, including the early formation stages. The frames from the video segments were then extracted into individual sequential images. Properties were found using the images such as the velocity fields, time evolution of multiphase Atwood number, and perturbation growth. Volume fractions were derived from mass discharge measurements and particle …

Airborne Counter-Uncrewed Systems With Runtime Assurance Control, Isaac J. Seslar

Mechanical Engineering ETDs

This thesis develops a response to the increase in the availability of the commercially available uncrewed aerial systems and is dedicated to the detection, classification, and tracking required to successfully neutralize when determined malicious. A requirement of actively avoiding obstacles using runtime assurance is addressed and designed to keep the hardware safe in potentially dangerous situations. This work will elaborate on the several components the test bed is comprised of, specifically the hardware and software portions that successfully solve the problem. The software encompasses the simulation, the multiple algorithms required for the tracking, and the machine learning required for detection …

Feasibility Study Of A Structural Electrolyte Containment Ring For Use In Thermal Batteries, Teal Harbour

Mechanical Engineering ETDs

The feasibility of a new thermal battery separator design utilizing a structural machined MACOR® ceramic is explored. The cylindrical ceramic “separator ring” maintains separation of cell electrodes while containing a LiCl-KCl molten salt electrolyte. Finite element analysis (FEA) results show the separator ring can withstand mechanical and thermal loading conditions representative of a thermal battery environment. Electrical Impedance Spectroscopy (EIS) was used to characterize impedance mechanisms. EIS data was also used to calculate and show conductivities of the experimental separators are comparable to a traditional pellet. Although discharge testing resulted in high current-pulse resistivities and low delivered capacity, the work …

Printing Parameter Determination And Characterization Of Additively Manufactured Kovar Steel, Will Macgreggor Davidson

Mechanical Engineering ETDs

Kovar (ASTM F15, UNS K94610) steel has many applications across Sandia National Laboratories but is best known within academia and industry for its glass-to-metal and glass-to-ceramic hermetic sealing capabilities. Successful printing parameters for a Renishaw AM400 to additively manufacture artifacts from Kovar steel powder have been determined. The printed test artifacts have been studied for ultimate tensile strength, density, surface roughness, hardness, bulk composition, and impact toughness. Longer throughput measurements such as porosity, coefficient of thermal expansion, and grain structure studies have been established for future delivery to the research team. Yet another delivery from this thesis research is a …

Fundamental Dislocation Solutions For Infinite And Semi-Infinite Media, Luo Li Mr

Mechanical Engineering ETDs

Much research has gone into determining stress fields of dislocation, as the understanding of dislocations is fundamental to understanding metal or crystal plasticity. In this thesis, the stress field of a rectangular dislocation loop in an infinite isotropic solid is developed for a Volterra-type dislocation with three non-zero Burgers vector components. Also, the stress and strain fields of a rectangular dislocation loop in an isotropic solid, which is a semi-infinite medium, are obtained here for a Volterra-type dislocation. Moreover, analytical and numerical verifications of the developed stress/strain fields are performed. This is done by ensuring the satisfaction of the equilibrium …

Numerical Evaluation Of Effective Thermal Response Of Heterogeneous Materials, Kevin W. Irick

Mechanical Engineering ETDs

Heterogeneity in materials leads to increased complication of physics, at the level or scale where heterogeneity exists, making analysis and material behavior predictions more difficult. As a result of the intricate descriptions or understanding of the physics required to determine the behavior of a heterogenous material or system, practitioners frequently prefer the use of effective properties or responses. This body of work is dedicated to performing computational analyses on the thermal behavior of heterogeneous materials and evaluating the corresponding analyses using formal verification approaches. Custom finite element method code was used for solving the heat equation in a variety of …