Engineering Commons^™

A Study On High-Frequency Bending Fatigue, Microhardness, Tensile Strength, And Microstructure Of Parts Made Using Atomic Diffusion Additive Manufacturing (Adam) And Additive Friction Stir Deposition (Afsd), Hamed Ghadimi

LSU Doctoral Dissertations

This dissertation reports the findings of several studies on the mechanical and microstructural properties of parts made using atomic diffusion additive manufacturing (ADAM) and additive friction stir deposition (AFSD). The design of a small-sized bending-fatigue test specimen for an ultrasonic fatigue testing system is reported in Chapter 1. The design was optimized based on the finite element analysis and analytical solution. The stress–life (S–N) curve is obtained for Inconel alloy 718. Chapter 2 presents the findings of ultrasonic bending-fatigue and tensile tests carried out on the ADAM test specimens. The S-N curves were created in the very high-cycle fatigue regime. …

Improvements To The Automatic Calibration Of Digital Focusing Color Schlieren Systems, Robert C. Frazee

LSU Master's Theses

As a diagnostic method, Schlieren imaging offers the unique ability to visualize flows with a completely non-intrusive method. By visualizing small changes in the refractive index of a fluid, Schlieren imaging is able to visualize changes in temperature, pressure, and composition. While historic Schlieren methods have been limited to providing largely qualitative information, modern Schlieren methods are able to extract quantitative information from flow phenomena. This is possible through either Background Oriented Schlieren (BOS) or Digital Focusing Color Schlieren (DFCS) methods. While BOS is relatively flexible, it requires a large amount of computational effort to process each frame of captured …

Centrifugal Microfluidic Platform For Solid-Phase-Extraction (Spe) And Fluorescence Detection Applications, Yong Zhang

LSU Doctoral Dissertations

Solid phase extraction (SPE) is a widely used method to separate and concentrate the target molecules in liquid mixture. Traditional SPE has to be conducted in the laboratory with professional equipment and skilled operators. The microfluidic and 3D printing technology have opened up the opportunity in developing miniaturized automatic instruments. The main contribution of this research is to integrate the SPE process on a novel centrifugal platform. Various valves are applied on the platform to help control the aqueous sample and reagents in the cartridge.

First, a centrifugal microfluidic platform was built for automatically detecting trace oil pollution in water. …

The Desorption Kinetics Of Methane From Nonaqueous Fluids For Enhanced Well Control, James Lee Nielsen Jr.

LSU Master's Theses

The mass transfer of a dissolved gas evolving to return to the gaseous phase from a liquid is governed by many parameters. This process affects the development of an oil and gas well due to the possibility of gas contamination occurring from either an influx entering the wellbore, or drilling through gas-bearing formations. Once this dissolved hydrocarbon gas circulates up the wellbore, it will begin to evolve from solution and poses a potential risk to drilling equipment, the environment, and personnel at a drilling rig. Being able to predict the behavior of gas desorption based on a known set of …

Combined Molecular Dynamics And Phase Field Simulation Of Crystal Melt Interfacial Properties And Microstructure Evolution During Rapid Solidification Of Ti-Ni Alloys, Sepideh Kavousi

LSU Doctoral Dissertations

Phase field method has become a popular tool to investigate the microstructure evolution during the solidification. Quantitative predictions using this method is still limited, and in this dissertation, we try to study this problem from different perspectives.

Most of the phase field models consider the solid-liquid interface to be in local equilibrium. Solidification during some manufacturing processes like selective laser melting, and electron beam additive manufacturing is rapid and far from equilibrium which can result in supersaturated solid solutions, segregation-free crystals, or metastable phases. Before obtaining any conclusions from the phase field simulations, we must know the answer for “which …

High Enthalpy Storage Thermoset Network With Giant Stress And Energy Output In Rubbery State And Associated Applications, Jizhou Fan

LSU Doctoral Dissertations

In this study, a new shape memory thermoset network with giant stress and energy output in rubbery state is synthesized and studied firstly since the low output in stress and energy in rubbery state has been a bottleneck for wide-spread applications of thermoset shape memory polymers (SMPs). Traditionally, stress or energy storage in thermoset network is through entropy reduction by mechanical deformation or programming. We here report another mechanism for energy storage, which stores energy primarily through enthalpy increase by stretched bonds during programming. As compared to entropy-driven counterparts, which usually have a stable recovery stress from tenths to several …

Transient Flow Analysis Of A Closing Blowout Preventer Using Computational Fluid Dynamics (Cfd), Daniel Barreca

LSU Master's Theses

Reliability of blowout preventers (BOPs) is crucial for drilling and production operations. Erosion of BOP components and hydrodynamic forces on rams may cause failure of BOP elements to seal the well. Transient computational fluid dynamics (CFD) simulations of fluids within the wellbore and BOP offer quantitative and qualitative data related to this reliability during the closure of various BOP components. Since limited research has been published in transient CFD simulations of closing BOPs, this thesis discusses challenges and solutions to simulating closing blowout preventers. Single component fluids are simulated through several BOP geometries such as annular preventers, pipe rams, and …

Liquid Jet Penetration And Breakup In A Free Supersonic Gas Jet, Hansen Jones

LSU Master's Theses

In the testing of today’s rocket engines, both on large scale vertical test stands and smaller subscale horizontal component testing stands, it is extremely important to be able to accurately quantify and mitigate the thermal and acoustic loads the engines will generate on test stand infrastructure. Due to the large number of parameters that must be considered for many cases, development of a multi-phase computational code is under way to properly analyze and design water spray cooling systems used at NASA’s Stennis Space Center (SSC) and across other NASA centers. As such, a small-scale experiment has been conducted at Louisiana …

Two-Phase Flow Regime Map For Large Diameter Pipes And High-Velocity Flows, Matheus Sigaki Capovilla

LSU Master's Theses

Worst-case-discharge (WCD) calculations are a pre-requisite for any new well to be drilled in the Gulf of Mexico (GoM). Models that were mostly developed for production rates prediction are currently used to calculate the WCD rate. These models were mostly developed for pipe diameters and flow velocities much smaller than those expected during WCD events. Therefore, these models may be miscalculating WCD rates.

This study aims at analyzing one of possible sources of errors in these models: the flow regime maps. The influence of diameter change on flow regimes is discussed. A thorough literature review is carried out for different …

Optimization Of The Hot Embossing Parameters And Sintering Characterization For Alumina/Berea Sandstone Sintering, Justin F. Robbins

LSU Master's Theses

The purpose of this study is to investigate the process of hot embossing on alumina based ceramics as a cost-efficient procedure for manufacturing microfluidic testing components. Alumina ceramics were used as an exploratory phase for the final objective of the project, manufacturing of Berea sandstone based ceramic samples. Previous research has shown potential in using hot embossing on Alumina based ceramics; however, complications with extrusion and micro-structure quality were observed. For this reason, the research performed aimed to produce Berea Sandstone based components by first improving upon the embossing quality of alumina ceramics.

The thesis first investigates changes in the …