Mechanical Engineering Commons^™

Experimental Study On The Fabrication Of Advanced Materials For Energy Applications Using High Energy Mechanical Milling, Ashvin Kumar Narayana Swamy

Open Access Theses & Dissertations

The reaction of aluminum (Al) powder with water has the potential for on demand hydrogen generation. Conventional Al powders, however, react with water slowly due to a highly protective oxide layer on the particle surface. Current methods for Al activation involve harmful and expensive materials. The nano-scale Al powders also remain very expensive and have problems such as a large amount of oxide on the surface. The use of aluminum in an energy generation cycle is also hindered by the fact that, although Al is the most abundant metal in the Earth's crust, its recovery from ore consumes a lot …

Thermal Barrier Coatings (Tbc's) For High Heat Flux Thrust Chambers, Christopher Michael Bradley

Open Access Theses & Dissertations

The last 30 years materials engineers have been under continual pressure to develop materials with a greater temperature potential or to produce configurations that can be effectively cooled or otherwise protected at elevated temperature conditions. Turbines and thrust chambers produce some of the harshest service conditions for materials which lead to the challenges engineers face in order to increase the efficiencies of current technologies due to the energy crisis that the world is facing. The key tasks for the future of gas turbines are to increase overall efficiencies to meet energy demands of a growing world population and reduce the …

Development And Testing Of An Ignition Physics Test Facility And An Oxygen/Methane Swirl Torch Igniter, Jesus Roberto Flores

Open Access Theses & Dissertations

There are many advantages to LOX/methane propulsion, such as in-situ resource utilization from Mars and the Moon, and simplicity of ground operations due to its non-toxic nature. There exists a lack of fundamental understanding of the ignition physics, and flame characteristics of these propellants when related to rocket propulsion, which has created undesirably long design cycles and flight hardware that is not optimized. Motivated by these issues, a study of the ignition physics of a shear coaxial injector is proposed, in which the flow field dynamics and ignition transients will be observed through a visually accessible combustion chamber. The main …

A Damage-Trap Interfacial Design To Improve Impact Resistance Of Polymers, Md Shariful Islam

Open Access Theses & Dissertations

Polymer materials such as Polycarbonate (PC), Polymethyl methacrylate (PMMA) have numerous applications in transparent armor which includes body and face shield, helmet, windows of the armored vehicle etc. The most challenging part of these applications is to ensure the safety of the people. These materials are often subjected to impact loading, so it is important to study the failure of these materials under impact loading. An experimental study has been made to investigate the impact damage in transparent layered materials. Impact experiments were carried out on various monolithic specimens and layered specimens for both two types of materials at different …

Development Of A Thermal Imaging Feedback Control System In Electron Beam Melting, Emmanuel Rodriguez

Open Access Theses & Dissertations

The Electron Beam Melting (EBM) process is a promising technology in the rapid manufacturing of metal components. EBM has the potential to reduce the cost of metal parts by minimizing the use of raw materials and machining time. The EBM technology has several advantages over other additive manufacturing (AM) technologies of metal, such as manufacturing speed and mechanical properties of the finished parts. For the process to be accepted in the aerospace industry as a flight-ready manufacturing technology, however, improved control and feedback must be implemented in the building process for better part quality and uniform production in manufacturing. As …

Inkjet Based Personalized Screening Platform For Cancer Therapy, Jorge Ivan Rodriguez

Open Access Theses & Dissertations

The new paradigm of personalized medicine is beginning to affect clinical practice. In particular, many of the advances in genomics and proteomics have made personalized screening and therapeutic inventions possible. On chip, cellomics approaches to screening and intervention are becoming more commonplace. Cancer therapies may benefit from the rise in `-omics' technologies. In addition, the availability of rapid screening data is crucial to mitigate cancer propagation and increase the possibility of patient recovery. This study is an endeavor to develop a cellomic anticancer drug screening process based on inkjet printing. Previous research has demonstrated that inkjet based screening can reliably …

Development Of `Lick And Stick' Passive Wireless Temperature Sensor For Harsh Environment, Hasanul Karim

Open Access Theses & Dissertations

Wireless passive temperature sensors have been receiving increasing attention due to the ever-growing need of higher energy efficient and precise monitoring of temperatures in high temperature energy conversion systems such as gas turbines and coal-based power plants. Unfortunately, the harsh environment such as high temperature and corrosive atmosphere present in these systems has significantly limited the reliability and increased the cost of current solutions. Therefore, this research project presents the concept and design of a low cost, passive, and wireless temperature sensor that can withstand high temperature and harsh environment. The temperature sensor was designed following the principle of metamaterials …

Development Of Advanced Polymer Nanocomposite Capacitors, Md Rajib

Open Access Theses & Dissertations

With the development of modern technology, the demand of high energy density dielectric capacitor devices is increasing for its significant role in stationary power systems, mobile devices, and pulse power applications. Among the different energy storage devices, polymer film based dielectric capacitor is still one of the most widely used energy storage devices mainly due to its high energy density, significant higher charge/discharge rate and low cost. To further enhance the energy density, high dielectric ceramic inclusions have been embedded in the polymer matrix; however, the temperature influence on the energy density has not been investigated. Therefore, in this research …

The Development Of Self-Supported Electromechanical Structures Using Fused Deposition Modeling, Jorge Ramos-Almeida

Open Access Theses & Dissertations

Recent research has focused on the fabrication freedom of 3D printing to create not only conceptual models but also final end-use products. In the last decade, several research groups have reported embedding electronic components and electrical interconnects into 3D printed structures during process interruptions; however, to date there is an absence of fabricated devices with electromechanical functionality for parts fabricated in a single Additive Manufacturing (AM) build sequence.

The focus of this research is the use of Fused Deposition Modeling (FDM) to manufacture a self-supported electromechanical motor. FDM is an AM process capable of building parts in a layer-by-layer fashion. …

Effect Of Hafnium-Incorporation On The Microstructure And Dielectric Properties Of Cobalt Ferrite Ceramics, Stephen Josiah Wells

Open Access Theses & Dissertations

The effect of hafnium ion (Hf⁴⁺) incorporation in cobalt ferrite (CFO) was studied. Samples of Hf substituted CFO ceramic (CoFe_2-xHf_xO₄), were synthesized in the laboratory with hafnium concentrations ranging from x=0.000 to x=0.200. X-ray diffraction scans show that the Hafnium CFO crystalizes in the inverse spinel phase. Inclusion of hafnium causes lattice expansion, increasing the lattice parameter from 8.374 í? for pure CoFe2O4 to 8.391 í? for the highest concentration of hafnium tested (x=0.020). The dielectric properties of CFO are greatly enhanced by inclusion of hafnium. The enhancement is due to the …

Investigation Of The Radiative Heat Release Factor Of Premixed Oxy-Syngas Flames, Martin De La Torre

Open Access Theses & Dissertations

A significant part of the United States is being powered by combustion devises relying on coal since it is abundant and is a high emitting source of electricity per unit energy, however; the burning of this fuel is responsible for a significant contribution for the pollutant emissions causing global warming. Because coal is one of the main sources of energy in the U.S. and around the globe, the scientific community has been investigating ways to meet current and future governmental emission requirements. It is now well established that radiating heat from the flame is a major contributor of the heat …

Pressure And Heat Flux Effects On The Heat Transfer Characteristics Of Liquid Methane, Chance Paul Garcia

Open Access Theses & Dissertations

The heat transfer effects on liquid methane are investigated with the use of a carbo-thermal rig at the Center for Space Exploration Technology Research (cSETR) located at the University of Texas at El Paso (UTEP). The cSETR carbo-thermal rig design approach is presented along with the design of a methane condensing mobile unit (MCMU) to supply the laboratory and rig with liquid methane. The proposed research will generate useful insight in to heat transfer coefficient behavior, non-dimensional correlations, different flow conditions, varied inlet conditions, and varied heat flux for a subscale test article applicable to a regenerative cooled rocket engine …

Nanocomposite And Mechanically Alloyed Reactive Materials As Energetic Additives In Chemical Oxygen Generators, Marco Antonio Machado

Open Access Theses & Dissertations

Chemical oxygen generators are widely used for aircraft, spacecraft, submarines, and mine rescue. Oxygen-generating compositions typically include alkali metal chlorate or perchlorate that decomposes at increased temperatures, a transition-metal oxide as a decomposition catalyst, and a metal fuel that reacts with part of the produced oxygen to provide heat for a self-sustained propagation of the decomposition/combustion wave. To increase the oxygen yield per unit mass, it is of interest to minimize the amount of metal fuel, but decreasing its content leads to pulsating combustion and undesired fluctuations of the oxygen flow rate. This work explores the feasibility of replacing iron …

Process Study And Control Of Electron Beam Melting Technology Using Infrared Thermography, Jorge Mireles

Open Access Theses & Dissertations

An IR camera was installed in an Arcam A2 system (Arcam AB, Mölndal, Sweeden) and layer-by-layer image acquisition was achieved. The camera's capability to detect manufacturing defects was evaluated by implementing computer vision techniques using LabVIEW measurement and programming software (National Instruments, Austin, TX). Thermal maps acquired by the IR camera allowed layer-by-layer part temperature to be recorded. A core objective of this research was to study the impact of processing temperature on EBM-fabricated Ti-6Al-4V parts and achieve controlled mechanical properties. In this research, build variations were achieved by modifying parameters that change processing temperature from the standard processing temperature. …

A Block Operator Splitting Method For Heterogeneous Multiscale Poroelasticity, Paul M. Delgado

Open Access Theses & Dissertations

Traditional models of poroelastic deformation in porous media assume relatively homogeneous material properties such that macroscopic constitutive relations lead to accurate results. Many realistic applications involve heterogeneous material properties whose oscillatory nature require multiscale methods to balance accuracy and efficiency in computation.

The current study develops a multiscale method for poroelastic deformation based on a fixed point iteration based operator splitting method and a heterogeneous multiscale method using finite volume and direct stiffness methods. To characterize the convergence

of the operator splitting method, we use a numerical root finding algorithm to determine a threshold surface in a non-dimensional parameter space …

Assessment Of Abaqus Capabilities For Crack Growth And Calculation Of Energy Release Rate, Luis Alonso Hernandez

Open Access Theses & Dissertations

The purpose of this study was to benchmark ABAQUS modeling capabilities for crack propagation and calculation of energy release rate against closed-form analytical solutions. The crack growth capability for this study was evaluated using the following techniques: virtual crack closure technique (VCCT), X-FEM coupled with VCCT, and X-FEM coupled with cohesive segments. The capability of calculating the energy release rate was assessed by using the J-integral routine. A Double Cantilever Beam (DCB) specimen was used to conduct the study for mode I propagation, and a mixed mode bending (MMB) specimen was used to study the propagation for mixed mode I/II …

New Topics On Nanoindentation Of Polymers And Composite Materials, Ricardo Martinez-Hernandez

Open Access Theses & Dissertations

In this study, nanoindentation was used to determine Young's modulus of homogeneous plastic materials as well as inhomogeneous epoxy woven fabric composites using various indenters. In the first part, homogeneous PMMA and polycarbonate were characterized using conical and spherical indenters. The conventional approach of the inverse analysis was modified in order to account for effects obtained during spherical nanoindentation. The experimental results were verified using FEA analysis in ABAQUS. It was found that viscous effects were present in conical nanoindentations which led to an overestimation of contact stiffness. The second part, the response of carbon and glass fiber woven fabric …