Mechanical Engineering Commons^™

Creating Multi-Functional G-Code For Multi-Process Additive Manufacturing, Efrain Aguilera Jr

Open Access Theses & Dissertations

Additive manufacturing (AM) started over thirty years ago and with it a manufacturing revolution that moves industrial production into the personal home. With recent interest shifting into multi-functional parts fabricated through AM technologies, unified systems are being developed. Merging different manufacturing technologies into one single machine is a challenge but undergoing research has shown promise in the development of multi-functional systems. Concurrent work is being done in the software, automation, and hardware aspect of multi-functional systems. An effort to use industry compatible Computer Aided Design (CAD) software to design multi-functional parts including circuits, micro-machining, and foil embedding then exporting and …

Mechanically Activated Combustion Synthesis Of Molybdenum Borosilicides For Ultrahigh-Temperature Structural Applications, Alan Alberto Esparza Hernandez

Open Access Theses & Dissertations

The desire to improve the efficiency of power generation gas-turbines has led to a relentless quest for new, ultrahigh-temperature structural materials to replace the current nickel-based superalloys. These materials have reached the maximum allowable operating temperature determined by the melting temperature of these alloys, which is about 1150 °C. These materials could be replaced by molybdenum silicides and borosilicides based on Mo5SiB 2 (T2) phase due to their high melting point and mechanical properties. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at elevated temperatures. One novel approach to improve these properties is …

Combustion Of Novel Thermite Mixtures For Iodine Generation, Sergio Emanuel Guerrero

Open Access Theses & Dissertations

Halogen-containing reactive materials could be used for mitigating the spread of hazardous, active biological microorganisms aerosolized as a result of explosion. The present work exhibits experimental results on the combustion of mechanically alloyed aluminum-iodine (Al-I2) powder mixed with Fe2O3, CuO, MoO3, Bi2O3, and I2O5. Wet mixing was used to prepare the samples, which were then compacted into pellets and ignited with a CO2 laser. A chamber was designed and built to accommodate for combustion and collection of products, and the available laser ignition setup was modified to enable combustion experiments with rapidly burning gas-generating mixtures. High-speed video recording was used …

Manufacturing And Mechanics Of Polymer Matrix Composites, Md Shariful Islam

Open Access Theses & Dissertations

Fiber-reinforced composite materials are widely used in the aerospace and automobile industries. Their strength-to-weight and stiffness-to-weight ratios make them suitable to be used in spacecraft, especially as cryogenic tank materials. One of the focus of this dissertation is to investigate the application of woven carbon and Kevlar® fiber composites as cryogenic tank materials. Tensile, bending and short beam shear tests are performed on rectangular specimens at room temperature and after cryogenic exposure (-196°C). It is found that the mechanical properties of these composite materials do not degrade significantly due to cryogenic exposure. It is observed that the failure mode took …

Computational Modeling Of A 60kw Oxy-Methane Direct Power Extraction Combustor, Omar Daniel Vidana

Open Access Theses & Dissertations

ANSYS Fluent was used to optimize components of a direct power extraction combustor. This includes the fuel injector, nozzle, and cooling units. Changes in the injector's inlet location impacted pressure and velocity distribution. An angle of 115 degrees with respect to the x-axis was found to increase distribution efficiency. Temperature and velocity data from the combustor and nozzle were calculated using NASA CEA and Fluent. Magnitudes of temperature and velocity for CEA and Fluent matched within 9% and 4%, respectively. For the cooling system it is expected that cavitation will not occur since the saturation temperature of water is not …

Design Of A Thermal Management System For An Oxy-Methane Direct Power Extraction Combustor, Jad Gerges Aboud

Open Access Theses & Dissertations

The overarching goal of this Thesis is to present the design of a thermal management system for an oxy-methane direct power extraction combustor. The design is initiated by performing a 2D analysis on the combustor geometry and then using these results in a 3D model. This is done by using results for heat transfer coefficient and temperatures found from the 2D simulation and importing these to the 3D model. The approach used here couples the combustion process, heat transfer through the chamber wall, and fluid flow behaviors in order to observe the thermal characteristics of the combustor during operation. This …

G-Code Generation For Multi-Process 3d Printing, Callum Peter Bailey

Open Access Theses & Dissertations

Since the inception of stereolithography in the 1980s, interest in 3D printing has exploded, with desktop 3D printers now commercially accessible to the general public. In recent years, next-generation multifunctional technologies have been developed, which combine 3D printing with other technologies such as wire embedding, foil embedding, CNC machining, and robotic component placement, enabling complex parts to be made on a single multifunctional machine.

However, the complexity of these integrated processes exceeds the capabilities of established design tools. To this end, this Thesis aims to develop a multi-functional design solution that can automatically generate final control code for next-generation multifunctional …

Structural Design Of Liquid Oxygen/Liquid Methane Robotic Lander Janus, Mariana Chaidez

Open Access Theses & Dissertations

As the attempt to send humans to Mars has gained momentum in the last decade, the need to find alternative propellants that are safer, less toxic, and yields a better performance has become apparent [1]. Liquid methane and oxygen have emerged as a suitable alternative. In addition, the incorporation of liquid methane/liquid oxygen into the propulsion system has demonstrated an increase in engine performance, as well as a reduction in the volume, size and complexity of the propulsion system. In an attempt to further understand the technologies that are possible to develop using liquid oxygen (LO2) and liquid methane (LCH4), …

Design And Performance Evaluations Of A Lo2/Methane Reaction Control Engine, Aaron Johnson

Open Access Theses & Dissertations

Liquid oxygen (LOX) and liquid methane (LCH4) are a propellant combination viewed as a potential enabling technology for spacecraft propulsion. Reasons why LOX/LCH4 is being used as an alternative propellant source include: it is less toxic than other propellants, it has the possibility to be harvested on extraterrestrial soil, LCH4 has a higher energy density than liquid hydrogen (LH2; commonly used on vehicle main engines), and LOX/LCH4 has comparable performance to other well-known propellant combinations. Through the continued partnership between the National Aeronautics and Space Administration (NASA) and the University of Texas at El Paso (UTEP) a LOX/LCH4 reaction control …

Microstructural Characterization Of High Velocity Oxy Fuel Coatings Of Inconel 718 And Iron Aluminides, Ana Cecilia Rios Ibanez

Open Access Theses & Dissertations

Thermal spray guns are used today to deposit metallic powders as homogeneous and durable coatings with low porosity onto metals. The objective is to improve their wear resistance and their corrosion resistance in order to withstand conditions such as abrasion and erosion. This can improve the life of turbines, generators and such devices in environments found in ultra-supercritical coal-fired (AUSC) boilers, steam turbines and gas turbines (Mohammed & Cabrera, 2014). Industries like manufacturing, automobile and especially in the sustainable energy area, have used this technique to improve component characteristics, extend product life, increase performance as well as reduce production and …

Development And Testing Of Oxygen/Methane Torch Igniter Technologies For Propulsion Systems, Luis Eduardo Sanchez

Open Access Theses & Dissertations

The development and testing of an oxygen/methane torch ignition system as well as the evaluation process of the system are presented with the purpose of characterizing the properties and performance of methane as a fuel in a propulsion system. The experimental approach to this Dissertation entails the development and testing of a swirl torch igniter under conditions that may be seen when feeding propellant from the main storage tanks: combinations of gaseous and liquid oxygen and methane. The experimental goal of this Dissertation is to display the range of operability of the igniter technology presented leading to stable and consistent …

Damage Tolerance And Assessment Of Unidirectional Carbon Fiber Composites, Mark David Flores

Open Access Theses & Dissertations

Composites are beginning to be used in a variety of different applications throughout industry. However, certification and damage tolerance is a growing concern in many aerospace and marine applications. Although compression-after-impact have been studied thoroughly, determining a damage tolerance methodology that accurately characterizes the failure of composites has not been established. An experimental investigation was performed to study the effect of stacking sequence, low-velocity impact response, and residual strength due to compression and fatigue. Digital Image Correlation (DIC) captured the strains and deformation of the plate due to compression. Computational investigations integrated non-destructive techniques (C-Scan, X-Ray) to determine the extent …

Structural, Dielectric, And Ferroelectric Characterization Of Lead-Free Calcium-Cerium Co-Doped Batio3 Ceramics, Juan Alberto Duran

Open Access Theses & Dissertations

Structure, morphology, and regulation of the dielectric properties via close-composition intervals is demonstrated for variable-cerium, constant-calcium co-doped barium titanate (Ba0.80Ca0.20CeyTi1-yO3; y=0.0-0.25; referred to BCCT). The effect of variable Ce-content on the structure and dielectric properties of BCCT is investigated. X-ray diffraction spectra confirms the studied samples are mainly in BT tetragonal phase with a small secondary phase detected as CaTiO3 in BCCT for y = 0.20 and 0.25. However, the lattice parameter reduction was evident with increasing Ce-content. Composition-driven dielectric constant leap (4,000-5,500) was observed from intrinsic BCT to BCCT for (y = 0.0-0.04). The temperature dependent dielectric constant showed …

Magnesium-Based Combustion Synthesis Of Advanced Materials For Energy And Space Applications, Armando Delgado

Open Access Theses & Dissertations

As energy problems become more challenging, interest in low-energy-consuming methods for the fabrication of materials increases. Combustion synThesis is one such method because it is sustained by reaction heat release instead of external energy input. In the present work, combustion synThesis approaches are applied to the production of construction materials from lunar and Martian regolith and to the fabrication of magnesium silicide (Mg2Si), a promising thermoelectric material for high-temperature applications. In both cases, magnesium (Mg) was used as one of the main reactants and similar experimental approaches were employed.

Recently, it has been proposed to use combustion of lunar regolith …

Design And Experimental Investigation Of An Oxy-Fuel Combustion System For Magnetohydrodynamic Power Extraction, Manuel Johannes Hernandez

Open Access Theses & Dissertations

A general consensus in the scientific and research community is the need to restrict carbon emissions in energy systems. Therefore, extensive research efforts are underway to develop the next generation of energy systems. In the field of power generation, researchers are actively investigating novel methods to produce electricity in a cleaner, efficient form. Recently, Oxy-Combustion for magnetohydrodynamic power extraction has generated significant interest, since the idea was proposed as a method for clean power generation in coal and natural gas power plants. Oxy-combustion technologies have been proposed to provide high enthalpy, electrically conductive flows for direct conversion of electricity. Direct …

Modeling And Testing Of Functional Materials For Energy System Applications, Hasanul Karim

Open Access Theses & Dissertations

Energy efficiency is one of the key concerns addressing the problem of global warming. Numerous research has been going on in order to improve the efficiency of energy conversion systems to reduce the polluted emission in the atmosphere. One of the approach is monitoring and maintaining the critical parameters of operation such as temperature to ensure the desired reactions, however, the harsh environment present in these systems makes the use of current temperature sensing solutions such very challenging to implement. Wireless temperature sensors are getting increasing attention as a potential solution, however, the need of energy storage devices such as …

Modeling And Characterization Of Piezoelectric Based Multifunctional Structures, Ricardo Martinez Hernandez

Open Access Theses & Dissertations

Continuous monitoring of high pressure and high temperature in energy system applications has been a developing research area in today’s energy sector. Multifunctional materials have the potential to provide real-time monitoring of structures where temperature and pressure sensing is critical to its performance and efficiency. In this study, multifunctional materials are studied by embedding piezoelectric materials with two ongoing technologies, woven fabric composites and additive manufacturing (AM). The AM technology allows the flexibility of embedding a sensor within the structure, all while not compromising the mechanical performance requirements. The “smart parts” are fabricated modifying the standard additive manufacturing process, using …

Design Of A 500 Lbf Liquid Oxygen And Liquid Methane Rocket Engine For Suborbital Flight, Jesus Eduardo Trillo

Open Access Theses & Dissertations

Liquid methane (LCH4)is the most promising rocket fuel for our journey to Mars and other space entities. Compared to liquid hydrogen, the most common cryogenic fuel used today, methane is denser and can be stored at a more manageable temperature; leading to more affordable tanks and a lighter system. The most important advantage is it can be produced from local sources using in-situ resource utilization (ISRU) technology. This will allow the production of the fuel needed to come back to earth on the surface of Mars, or the space entity being explored,making the overall mission more cost effective by enabling …

Through-Thickness Reinforcement For Woven Laminates, Alejandra G. Castellanos

Open Access Theses & Dissertations

Fiber reinforced polymer composites have gained popularity in aerospace and naval applications due to their tailorable mechanical properties and high strength-to-weight. Despite these advantages, between the layers of fabric (laminas), there is a resin-rich region known as interlaminar region, with no reinforcement which is very susceptible to damage. Different types of reinforcements have been tested for the interlaminar region. However, all of these methods have proved to decrease the in-plane properties due to damage to the fibers. In this Thesis, a new reinforcement technique with ZnO nanowires is proposed to increase the damage resistance. This Thesis describes the design, manufacturing …

Manufacturing And Characterization Of Energetic Materials, Carlos Alberto Catzin

Open Access Theses & Dissertations

Few products take several years of research effort to be synthesize yet disintegrate in scarcely millionths of a second when used. Despite their short lifespan energetic materials, particularly high explosives, are in demand as never before by the Aerospace, Defense, Energy, Gas, Mining, and Oil Industry for their unique properties. One class of high explosives known as polymer bonded explosives (PBXs) are popularly used in a wide variety of applications ranging from solid rocket propellants to the main explosive charge in conventional ammunitions. A key characteristic behind the popularity of PBXs in comparison to other high explosives is their handling …

Yttria Rich Tbcs As Candidates For Cmas Resistant Top Coats, Juan Jose Gomez

Open Access Theses & Dissertations

State of the art thermal barrier coatings (TBC) commonly made of 7-8 wt. % yttria stabilized zirconia (7YSZ) are used in modern gas turbines to generate a thermal protection to the underlying super alloy components. TBCs allow higher operating temperatures for hot gas path components, thus, generating higher engine efficiency. The infiltration of molten glassy mineral deposits composed of CaO-MgO-Al2O3-SiO2 (CMAS) represents one of the major threats in reducing performance and service life in aero and land based gas turbine engines. The CMAS deposits are ingested into the engine carried commonly in sand, runways debris, fly ash and volcanic ash. …

Analysis Of Road Vehicle Aerodynamics With Computational Fluid Dynamics, Christian Armando Mata

Open Access Theses & Dissertations

A road vehicles aerodynamics can be one of the most influential aspects of its performance. With the increased importance on fuel efficiency in recent years, new road vehicles are being developed smaller in size, with smaller displacement engines, as well as with improved aerodynamics. The aerodynamics of a vehicle can have a significant effect on its fuel efficiency, as well as other important aspects of the vehicles performance such as the top speed, acceleration, and handling. A study focusing on analyzing aerodynamic effects due to vehicle geometries such as wheels covered by the vehicles body in comparison to open wheels …

Modeling Of Piezoelectric Traveling Wave Rotary Ultrasonic Motors With The Finite Volume Method, Ivan Arturo Renteria Marquez

Open Access Theses & Dissertations

In 1983 Toshiiku Sashida developed a new motor concept called Piezoelectric Traveling Wave Rotary Ultrasonic Motor (PTRUSM). The advantages of these motors include high torque at low speed, absence of a generated magnetic field, and high potential for miniaturization. Unfortunately PTRUSMs have some disadvantages that limit the areas of applications for these types of motors. The disadvantages are a short operating life (about 1000 hours), small output power, and the need of a complex motor controller.

On one hand, these motors have been used in satellites, mobile phones, photocopiers, robotic arms, telescopes, automobiles, and camera autofocusing. On the other hand, …

Design Optimization Of Sandwich Core, Mohammad Tauhiduzzaman

Open Access Theses & Dissertations

Ultralight sandwich structures comprising of low-density core with stiff facings have attracted significant research interest for their considerable weight saving applications. The aircraft industries are focusing on decreasing the structural mass to lower the manufacturing and operating costs. Design analysis of the sandwich cores using finite element analysis has been developed as a promising concept to feature sandwich structures with maximum strength, stiffness, and reduced weight. To obtain multifunctional behavior of sandwich panels, a profound investigation of geometrical and mechanical properties in the transverse plane is required because it is very susceptible to any kind loadings. Structural optimization is one …

Flame Front Structures Studies Of Highly Turbulent Reacting Flow Over A Backward Facing Step Using Khz Oh-Ch Planar Laser Induced Fluorescence, Arturo Acosta-Zamora

Open Access Theses & Dissertations

In recent years, there has been a greater move in the scientific and political community to increase combustion efficiency and reduce emission levels; for this reason, it is crucial to gain a better understanding of combustion. Experimental work at relevant conditions and the data generated from these is needed in order to gain a better understanding of combustion; this data may also be used for validation and further refinement of computational models and simulations. The improvement of optical combustion diagnostics systems has opened new ways to explore these combustion processes. The testing of a high intensity turbulence combustion system is …

Development Of The Thermal Wire Embedding Technology For Electronic And Mechanical Applications On Fdm-Printed Parts, Daniel Abraham Marquez

Open Access Theses & Dissertations

Additive Manufacturing (AM) has increased in popularity and attracted much attention from many fields such as automotive, aviation, aerospace, and even the fashion industry. Since the early 2000s, Fused Deposition Modeling (FDM) technologies have been the most popular in the AM world ("Wohlers Talk" Popularity of FDM). These technologies have been mainly used for building parts for prototype and structural type of applications such as a fixture for components or a housing for mechanisms.

With the current state of the FDM technologies, the functionality of the parts that are printed are limited to the applications listed before or simply just …