Mechanical Engineering Commons^™

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 …

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 …

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 …

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 …

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 …

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 …

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 …

Performance Comparisons Of Personal And Professional-Grade 3d Printers, Alfonso Fernandez, Ryan Wicker, Francisco R. Medina, David Espalin

COURI Symposium Abstracts, Summer 2012

The recent emergence of personal 3D printers (i.e., systems that cost $5,000 or less) has engaged a new class of users including hobbyists, tinkerers, entrepreneurs, and do-it-yourselfers. Over 20,000 personal 3D printers were sold in 2011, and thus there is a need for users to understand the cost and performance of personal 3D printers as compared to low-cost professional-grade machines (i.e., systems that cost between $5,000 and $20,000). The cost, process time, material usage, and dimensional accuracy was assessed for select personal 3D printers and low-cost professional-grade systems. The study showed that the laminated object manufacturing (LOM) printer generated 80% …

Sic-Cnt Multifunctional Nanocomposites For High Temperature Structural, Thermoelectric And Sensing Applications, Salvador Sandoval, Luz I. Bugarin, Luz I, Arifur Chowdhury, Luisa A. Cabrera, Mujibur R. Khan

COURI Symposium Abstracts, Summer 2012

The purpose of this project is to study the thermal-electrical and mechanical properties of the Nanojunctions between Single-Wall Carbon Nanotubes (SWCNT) and Silicon Carbide (SiC). The mixture was done by spreading the nanoparticles in a solution of ethanol and SiC, then sintered to a solid sample of 10 mm x 10 mm x 35 mm, which was attached with Alumel (Ni-Al) wire using silver epoxy to form a circuit for recording during fracture testing. The carbon nanotubes used were approximately 60% semiconducting and 40% metallic. The themal-electrical effect changed when SWCNTs (at 2, and 5 wt%) were infused into SiC. …

Nanowire-Graphene Hybrids For Li-Ion Insertion, Philip A. Morton, Mohammad Arif I. Shuvo, Yirong Lin

COURI Symposium Abstracts, Summer 2012

Lithium ion batteries are one of the most popular energy storage devices due to its high energy density. However, their performance is hindered by the limited surface area of the anode. This research focuses on the use of graphene nanowire hybrids and their performance as anode material. These hybrid structures have a greater surface area then graphite, the most common anode material. Greater surface area will enhance lithium ion insertion, and thus improve battery performance. The graphene oxide (GO) will be synthesized using the Hummer’s plus method. The GO will be sonicated and reduced in an argon furnace to form …

Research And Development Of An Extremely Affordable Prosthetic Knee, Victor H. Duenas, Noe Vargas-Hernandez

COURI Symposium Abstracts, Summer 2012

The objective of this research and development work is to apply the design process in a prosthetic knee mechanism. The importance of human knee is founded in the provided mobility, body positioning and support of the body weight. But for amputees, limitations for everyday tasks imply a real challenge. The project scope a cycle involving the social need, the development and the supply of the solution layout. The motivation is to improve life quality through voluntary and independent human movement by providing a low cost knee design.

The design process requires the conceptual, embodiment, detail and evaluation phases to complete …

Research And Development Of An Expert System In Idea Generation Methods To Aid In The Engineering Design Process, Rodrigo Enriquez, Noe Vargas-Hernandez

COURI Symposium Abstracts, Summer 2012

The objective of this research is to develop an Expert System (i.e. software) to aid designers in selecting appropriate idea generation methods for their specific design situation. This expert system would help designers generate creative ideas more frequently, and hence better designs and better products for society. The first step is to understand the creative design process in detail; this involves the engineering design process, cognitive processes, and other related elements. This understanding is represented initially as a conceptual model. Following an Artificial Intelligence (AI) approach, this model is then developed into a Logical model that defines entities, attributes, and …

Scalability Study Of Explicit Finite Element Method On Shared And Distributed Memory Architectures, Leonardo Orea-Amador, Jack F. Chessa Ph.D.

COURI Symposium Abstracts, Summer 2012

Parallel architectures in computer systems are powerful tools for processing enormous amounts of information. The results of this research will illustrate their optimal usage by evaluating the scalability of the code Abaqus in the cases of domain decomposition and loop parallelization architectures. The scalability was analyzed using concomitant variation having the DoF (Degrees of Freedom) and CPU (Central Processing Unit) numbers as the variables. Abaqus jobs with less than 100,000 DoF showed similar scalability than that of jobs with more than 500,000. These results contradict the original hypothesis which proposed that small jobs would show poor scalability and vice versa. …

Feasibility Analysis Of Solid Particles As A Thermal Energy Storage Medium Using Fluidization Process, Sebastian De La Rosa^, Arturo Sepulveda, Vinod Kumar*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Computational Simulations Of Carbon Dioxide Flow In Porous Media For Carbon Sequestration Applications, Eduardo Cordero^, Jesus D. Ortega, Dustin Crandall, Grant Bromhal, Vinod Kumar*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Pore Network Model Construction From Ct Scanned Rock Samples For Carbon Sequestration Simulation, Daniel Llausas^, P. Delgado, Vinod Kumar*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

High Fidelity Thermocline Tracking Algorithm Using Weighted Essentially Non-Oscillatory Schemes, Claudia L. Guevara^, Kiran Kumar, Vinod Kumar*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Computational Models Of Sub-Divided Thermal Energy Storage Tanks Used In Concentrating Solar Power Plants With Parabolic Trough Collectors, Jesus D. Ortega ^, Vinod Kumar *

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Synthesis And Characterization Of Aluminum Doped Zinc Oxide Nanowires For Photovoltaic Devices And Semiconductors, Travis J. Wilson^, Md. Ashiqur R. Khan, Mohammad A. I. Shuvo, Miguel Mendoza, Matthew Garcia, Yirong Lin*, Chintalapalle V. Ramana*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Sic-Cnt Multifunctional Nanocomposites For High Temperature Structural, Thermoelectric And Sensing Applications, Luisa A. Cabrera^, Arifur Chowdhury, Onasis Garcia, Mujibur R. Khan*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Heat Exchanger Design And Development For Automotive Exhaust Waste Heat Recovery Using Thermoelectric Devices, Kazi S. Hassan

Open Access Theses & Dissertations

In this study several heat exchanger designs were constructed, tested, and the effect of the design on the overall efficiency and power generated by thermoelectric generators was measured. The thermoelectric elements were attached to the heat exchanger and hot gas passed through the system simulating automotive exhaust. An aluminum duct heat exchanger, a copper heat exchanger, and a heat exchanger with a twisted tape insertion were tested. The heat exchangers were all rectangular with similar dimensions and minimum thicknesses near the wall. The flow of exhaust gas was created by heated air flow ranging from 100-150 LPM. The cool side …

High-Order Central Finite-Volume Schemes For Atmospheric Modeling, Kiran Kumar Katta

Open Access Theses & Dissertations

Atmospheric numerical modeling has been going through drastic changes over the past decade, mainly to utilize the massive computing capability of the petascale systems. This obliges the modelers to develop grid systems and numerical algorithms that facilitate exceptional level of scalability on these systems. The numerical algorithms that can address these challenges should have the local properties such as the high on-processor operation count and minimum parallel communication i.e., high parallel efficiency. They should also satisfy the following properties such as inherent local and global conservation, high-order accuracy, geometric flexibility, non-oscillatory advection and positivity preservation properties. The goal of this …

Development Of A High Pressure Optically Accessible Combustor And Shear Co Axial Injector, Christopher David Navarro

Open Access Theses & Dissertations

A trend in the last decade in the field of propulsion and rocketry is leaning toward the use of the combination of Liquid Methane and Liquid Oxygen as propellant fuels. This is in contrast with the earlier trend of using Hydrogen systems and toxic hypergolic systems. The Multi-Purpose Optically Accessible Combustor (MOAC) and Shear Coaxial injectors have been developed to investigate injector design and combustion research involving Oxygen and Methane propellants. The MOAC is intended for the experimentation and research of combustion of liquid and gaseous propellants. Development of the MOAC system and versatility to use a number of injector …

Investigation Of A Water Desalination Method Via A Humidification-Dehumidification Process Using Hvac Technology, Juan Antonio Cornejo

Open Access Theses & Dissertations

Potable water is becoming a scarce resource in many arid regions of the world. An experimental unit was designed and constructed to examine and characterize the production capabilities of a humidification-dehumidification (HDH) desalination process. An HDH cycle offers a viable, technologically light, alternative for producing fresh water from brackish water because the low relative humidity air is infused with water vapor through evaporation by means of conventional heating, ventilation and air conditioning (HVAC) components. The evaporation process effectively separates salts and suspended solids from the brackish feed-water. Desalinated water is subsequently recovered by extracting the water vapor from the moist …

Cryogenic System Development For Lox/ Hydrocarbon Propulsion Research, Francisco Pineda

Open Access Theses & Dissertations

A propulsion research facility is being developed at the Center for Space Exploration Technology Research (cSETR) at the University of Texas at El Paso (UTEP). These facilities were developed in order to meet new research demand for Liquid Oxygen (LOX)/Liquid methane (LCH4) experiments. The main goal of this system is to produce in-house liquid methane and supply propellants to their respective test set up in a cryogenic state. The work presented describes the design, development, and operation of a liquid methane condensation system and a cryogenic delivery feed system. The condensation system design will allow for a production of methane …

Oxidation Of Borides And Carbides With Y2o3 And Ta Additions, Salvador Manuel Rodriguez

Open Access Theses & Dissertations

The study presented here describes an investigation of an oxidation scale of a fully-sintered Y2O3-ZrB2-TiC composite exposed in air at 1173K. Upon oxidation of the boride/carbide, a ZrO2-TiO2 was expected to form similar to the ZrO2-SiO2 dual scale of an oxidized ZrB2-SiC. The 47wt% Y2O3-38wt%ZrB2-16wt%TiC composite formed a dual scale consisting primarily of an Y2O3-ZrO2-TiC inner scale with an outer scale of ZrO2-TiO2-Y2O3.

The samples oxidized with a parabolic layer growth allowing the calculation of the effective diffusion coefficient indicating that the oxidation was controlled by oxygen ingress through primarily the ZrO2-Y2O3 phase. The oxygen potential between the inner layer …

Investigation On A Gas-Solid Fluidized Bed Hydrodynamics Using A Non-Intrusive Technology To Visualize Flow Field, Md Rashedul Hasan Sarker

Open Access Theses & Dissertations

The biggest challenge for 21st century is to fulfill global energy demand and at the same time reduce detrimental impact on environment. Gasification technology can meet the requirement and also reduce emission without compromising its performance. In coal gasification, instead of burning coal completely a partial combustion takes place with presence of steam and limited amount of oxygen. In this controlled environment a chemical reaction takes place and produces a mixture of clean synthetic gas. Gas-solid fluidized bed is one type of gasification technology. During gasification mixing behavior of solid (coal) and gas and their flow pattern very complicated to …

Investigation Of A Water Desalination Method Via A Humidification-Dehumidification Process Using Hvac Technology, Juan A. Cornejo

Open Access Theses & Dissertations

Potable water is becoming a scarce resource in many arid regions of the world. An experimental unit was designed and constructed to examine and characterize the production capabilities of a humidification-dehumidification (HDH) desalination process. An HDH cycle offers a viable, technologically light, alternative for producing fresh water from brackish water because the low relative humidity air is infused with water vapor through evaporation by means of conventional heating, ventilation and air conditioning (HVAC) components. The evaporation process effectively separates salts and suspended solids from the brackish feed-water. Desalinated water is subsequently recovered by extracting the water vapor from the moist …

Impact Testing Of Zirconium Diboride, Mark David Flores

Open Access Theses & Dissertations

Refractory ceramic materials such as zirconium diborides (ZrB2) have been excellent candidate materials for application in turbine blades, leading edge surfaces of high mach aircraft and high temperature applications. This is due to their good strength at high temperatures (T>1800°C). But questions on their ultimate durability at such temperatures remains an issue, especially with respect to foreign object impact damage as well as oxidation. Little characterization of such materials of the impact durability of such materials at very high temperatures has been performed - In this talk an experimental approach for the impact testing of ceramic materials at elevated …

Numerical Analysis Of Single Tank Thermocline Thermal Storage System For Concentrated Solar Power Plant, Samia Afrin

Open Access Theses & Dissertations

The overall efficiency of a Concentrating Solar Power (CSP) plant depends on the effectiveness of Thermal Energy Storage (TES) system. A Single tank TES system has potential to provide effective solution. In a single tank TES system, a thermocline region, which produces the temperature gradient between hot and cold storage fluid by density difference, is used. Preservation of this thermocline region in the tank during charging and discharging cycles depends on the uniformity of the velocity profile at any horizontal plane. One of the major challenges for the single tank thermocline is actually maintaining the thermocline region in the tank, …