Mechanical Engineering Commons^™

Real-Time Intelligent And Multi-Spectral Inspection Of Structural Components, Mst Mousumi Rizia

Open Access Theses & Dissertations

Conventional, manual inspection methods are the most commonly used inspection approaches to this day; that cause downtime and can be erroneous due to their repetitive nature, heavy workload, and human error. The overarching goal of this work is to advance structural inspection with intelligent and autonomous techniques across infrastructures. In particular, this project will develop path-planning schemes for close navigation around the structures and intelligent algorithms for crack and corrosion detection.

The introduced novel navigation method uses advanced manufacturing techniques to generate aerial inspection trajectories in GPS-denied areas. The proposed method is validated using the `Gazebo' robotics simulator; the results …

A Probabilistic Creep Constitutive Model For Creep Deformation, Damage, And Rupture, Md Abir Hossain

Open Access Theses & Dissertations

The structural analysis of Industrial Gas Turbine (IGT), Aeroengine, Gen IV nuclear components under in-service conditions at various stress and temperature are susceptible to time-dependent creep deformation and creep induced failure. Such failure phenomena are exacerbated by the randomness in material properties, oscillating loading conditions, and other sources of uncertainty. The demand for physically based probabilistic creep modeling is highly sought by alloy designers. The objective of this study is to develop and validate a probabilistic creep-damage model incorporating multi-sources of uncertainty to replace the traditional deterministic and empirical decision-based modeling. In this study, the deterministic Sine-hyperbolic (Sinh) creep-damage model …

High Pressure High Heat Flux Pool Boiling Test Facility Design To Investigate Nucleation Boiling Heat Transfer Enhancement Using Micro/Nano-Scale Engineered Structures, Omar Hernandez Hernandez Rodriguez

Open Access Theses & Dissertations

Developing efficient heat dissipation technologies is of critical importance towards the development and the commercialization of next-generation compact and high-performance electronic devices, cooling systems, power generation systems and chemical processing units, as well as retrofitting the existing thermal management schemes. As such, phase change heat transfer systems, more specifically boiling heat transfer systems, have attracted significant attention due to their ability to extract a large amount of latent energy stored within the fluid. Pool boiling is an efficient mode of phase change heat transfer processes accompanied by nucleation of vapor bubbles from liquid on to the hot surfaces, bubble growth, …

Development Of A Multi-Axis Wire Embedding Device For A Large Area Thermoplastic Pellet-Fed Additive Manufacturing System, Christopher Jasiel Minjares

Open Access Theses & Dissertations

This research focused on the development and implementations of a six degrees of freedom (6DOF) articulated arm onto a Big Area Additive Manufacturing (BAAM) system to interact with complex 3D geometries. BAAM is a large-scale machine which falls under material extrusion additive manufacturing (AM) - a process that selectively dispenses molten plastic layer-by-layer. The development of the 6DOF articulated arm required a mechanical design which went through several iterations before getting to the final design. Also, implementation of the tool was performed with the help from Cincinnati Incorporated (CI) which is the company that developed the BAAM.

First, the mechanical …

Multi-Wavelength Pyrometry For Emissivity Mapping And Accurate Surface Temperature Measurement In Powder Bed Fusion Systems, Md Moinuddin Shuvo

Open Access Theses & Dissertations

Accurate surface temperature measurement within powder bed fusion (PBF) systems during fabrication remains elusive for many reasons, despite the importance of knowing temperature for improving part quality, process control, repeatability and reproducibility, simulation capabilities, and more. Multi-wavelength (MW) pyrometry has been used previously to measure off-axis temperatures of a small region (~2.6mm in diameter) within an electron beam PBF (EBPBF) system. While this small region measurement makes it difficult to get a full field temperature map of the powder bed, it also allows for inline (on-axis) with laser temperature measurements for laser PBF (LPBF) systems. The MW pyrometry technique determines …

Brian Valdez - Dynamics And Control Of A 3-Dof Manipulator With Deep Learning Feedback, Brian Orlando Valdez

Open Access Theses & Dissertations

With the ever-increasing demands in the space domain and accessibility to low-cost small satellite platforms for educational and scientific projects, efforts are being made in various technology capacities including robotics and artificial intelligence in microgravity. The MIRO Center for Space Exploration and Technology Research (cSETR) prepares the development of their second nanosatellite to launch to space and it is with that opportunity that a 3-DOF robotic arm is in development to be one of the payloads in the nanosatellite. Analyses, hardware implementation, and testing demonstrate a potential positive outcome from including the payload in the nanosatellite and a deep learning …

Low Weight Design Of A Pressure-Fed System For A Small Payload Launch Vehicle, Lucero Buendia

Open Access Theses & Dissertations

Carbon fiber reinforced polymer (CFRP) composites have become of great interests to aerospace industries because of their low-cost, lightweight and their tailorable mechanical properties. In aerospace structures, for example, heavy metals have been used in cryogenic fuel and oxidizer tanks for over 50 years. However, weight savings can be substantial if materials such as composites are used instead. From Delta IV heavy-lift launch vehicle it is known that cryogenic composite tanks can save approximately up to 30% of weight in fuel and oxidizer tanks. Although there is a wealth of studies in the mechanical behavior of composites at room temperature, …

Structure-Property-Performance Evaluation Of Refractory Metal Incorporated Gallium Oxide Thin Films For Extreme Environment Applications, Anil Krishna Battu

Open Access Theses & Dissertations

An approach is presented to design refractory-metal (RM) incorporated Ga2O3-based materials with controlled structural, mechanical, and optical properties. A model system based on molybdenum (Mo) doped Ga2O3 (GMO) has been considered to elucidate the combined effect of RM-doping and processing parameters on the properties and oxygen sensor performance of GWO nanomaterials. The molybdenum (Mo) content in Ga2O3 was varied from 0 to 11 at% in the sputter-deposited Ga-Mo-O films. Molybdenum was found to significantly affect the structure and optical properties. While low Mo content (≤4 at%) results in the formation of single-phase (β-Ga2O3), higher Mo content results in amorphization. Chemically …

Velocity Measurements Using A Piezoelectric Plate As A Sensor, Paul Perez

Open Access Theses & Dissertations

In this study, the voltage output from a piezoelectric sensor placed in a test section is used to predict flow velocity changes. The piezoelectric made of PZT is thought to be advantageous due to its fast response time, potential durability at higher temperatures, and self-powered characteristics. Having said that this sensor could be implemented into the Hybrid Performance Project built by NETL to characterize and mitigate the probability of compressor surge and stall. The problem arises because of the added large volume between compressor and gas turbine and resultant changes to system fluid dynamics. The effect of the piezoelectric sensor …

Design Of A Linerless Cryogenic Propellant Tank For A Small Payload Launch Vehicle, Itzel Adriana Torres

Open Access Theses & Dissertations

The need of lightweight launch vehicles that will reduce the cost and make flights more frequent into orbit has called for an increase of composite materials in the aerospace industry. Composite material’s low thermal conductivity, high resistance to fatigue, and most importantly, low-weight can greatly reduce the cost of launch operations by decreasing the overall weight of the vehicle. Weight and cost savings are critical because any amount of weight that is saved can be directly applied as an additional amount of payload capability. The tanks on space vehicles are pressurized vessels that store fuel at cryogenic temperatures and have …

Computational Methods For Creep Modeling, Ricardo Vega

Open Access Theses & Dissertations

Creep is an important phenomenon present in the power generation and aerospace industry. Creep is a mechanism that degrades the quality of a part, such as the turbines used in different industries, when elevated temperatures and loads are applied. Creep damage can cause critical failures that can cost millions of dollars and as such, prevention is important. A multitude of creep models exist to help with design and failure prevention. These models are applied using computational tools which allows the engineer to properly predict the life of a part or other material properties. In this work various creep numerical optimization …

Synthesis And Advanced Manufacturing Of Polymer Structures And Their Composites, Bethany Rose Wilburn

Open Access Theses & Dissertations

The following research work performed embodies three unique studies of polymer structures and their composites. In general, polymers are viscoelastic, insulative materials that are used for a wide variety of applications within industrial, aerospace, and biomedical fields. Polymers have been studied and optimized for any particular use by chemically synthesizing unique micro-structures, altering the physical properties through fabrication and post-processing, and utilizing 3D printing to achieve complex geometries. In the past decade, additive manufacturing (AM) has drawn extensive attention across academia, industry, and government agencies. It offers unprecedented advantages such as design freedom, rapid prototyping, and customization. In this work, …

Qualification And Implementation Of A Liquid Oxygen/ Liquid Methane Data Acquisition System, Zachary Welsh Welsh

Open Access Theses & Dissertations

One of the primary goals of the MIRO Center for Space Exploration and Technology Research (cSETR) is the design and testing of liquid oxygen and liquid methane rocket engines. As of this thesis’ time of writing, two engines are currently undergoing testing at the center’s Technology Research and Innovation Acceleration Park (tRIAC), located in Fabens, Texas. The engines vary in scale starting with a 5 lbf Reaction Control Engine (RCE) to a 500 lbf engine dubbed the Centennial Restartable Oxygen Methane Engine (CROME). It was necessary to develop a control and data acquisition system to support these various test campaigns, …

The Dynamic Transition Of A Vertical Take-Off And Landing Drone, Luis Carlos Calvo Jr.

Open Access Theses & Dissertations

Unmanned aerial vehicles, or UAVs, are small pilotless aircrafts that are remotely controlled through a ground control station. They have increased in popularity because of their applications and the advantages that each UAV can provide based on their need. There are many types of UAVs, but this study focuses on a type of Vertical Take-Off and Landing (VTOL) UAV that is known as the Albatross UAV. This UAV was manufactured by a company known as Applied Aeronautics, and configurations were made to change the fixed-wing (FW) UAV to a VTOL UAV. This study was done to find methodologies to simulate …

Design And Additive Manufacturing Of Shape Recovery Polymer Lattice Structure, Chien-Chun Chou

Open Access Theses & Dissertations

Studied mechanical properties of 3D printed metamaterials of BCC, FCC, and BFCC structure.

Uav Parameter Estimation Through Machine Learning, Andres Enriquez Fernandez

Open Access Theses & Dissertations

Parameter identification of Unmanned Aerial Vehicles (UAV) is very helpful for understanding cause-effect relationships of physical phenomenon, investigating system performance and characteristics, fault diagnostics, control development/tuning, and more. Traditional ways of performing parameter identification involve establishing a mathematical model that describes the system's behavior. The equations in the model contain parameters that are estimated indirectly from measured flight data. This parameter identification process requires knowledge of the physics involved. Also, it necessitates a careful consideration of the aircraft instrumentation for accurate measurements. It also requires careful design of the flight maneuvers to ensure thorough excitation of the flight dynamics involved. …

Development Of An Automated Ultrasonic Wire Embedding Process For Use With Material Extrusion Additive Manufacturing And Rapid Electronics Fabrication, Nikki L. Martinez

Open Access Theses & Dissertations

Polymers have been used in Additive Manufacturing (AM) by many industries for rapid prototyping. Parts created using polymer AM however are known to be relatively expensive thus limiting them to small volume production and making them inapplicable for mass production, while their inherent porous and anisotropic properties make them mechanically inferior to parts made using traditional methods such as injection molding. As projects demand more efficient designs, and at the same time ask for more complex features, AM, combined with other manufacturing processes, like Ultrasonic Wire embedding, can streamline and consolidate assemblies. In the realm of composite and multifunctional assemblies, …

The Effect Of K2co3 Concentration In Kerosene Emulsions On Spray Droplet Sizes For A Magnetohydrodynamic Power Generator, Alejandra Castellano

Open Access Theses & Dissertations

Potassium carbonate (K2CO3) is an effective seeding material to introduce potassium vapor in oxy-fuel combustion to create a conductive plasma. Injecting potassium carbonate before combustion promotes particle volatilization and improves the generation of potassium vapor. This can be achieved by emulsifying a potassium carbonate solution with kerosene. Several studies have investigated creating stable emulsions with kerosene with water by using differing surfactants. However, the effects of using varying concentrations of K2CO3 dissolved in deionized water have not been fully explored. Based on methods of creating successful emulsions, the development of a successful mixture comprised of kerosene and K2CO3 solution is …

An Accelerated Creep Testing Program For Nickel Based Superalloys, Robert M. Mach

Open Access Theses & Dissertations

In order to improve the energy production within the United States, new materials are developed with the goal of increased functionality. These materials are required to perform at extreme pressures and temperatures (up to and beyond 200MPa and 650â??) as well as be sustainable beyond 105 hours. Before developing these materials into components for power generation, mechanical testing is required to better understand the behavior of these materials at various loads and temperatures. The longest of these tests is the conventional creep test which is a real time test that can beyond 105 hours depending on service conditions. Hundreds of …

Machine Learning Analysis To Characterize Phase Variations In Laser Propagation Through Deep Turbulence, Luis Fernando Rodriguez Sanchez

Open Access Theses & Dissertations

The present Dissertation is focused on the analysis of the atmospheric conditions of a turbulent environmental system and its effects on the diffraction of a laser beam that moves through it. The study is based on the optical communication of two labs placed at the summit of two mountains located in Maui, Hawaii. The emitter system is located at the Mauna Loa mountain and the receiver at the Haleakala. The distance between both mountains is 150 km. The emitter system is at a height of 3.1 km and the receiver at 3.4 km. The maritime environment at the location experiences …

Additive Manufacturing Of Engineered Material Systems For Energy Applications, Luis Angel Chavez

Open Access Theses & Dissertations

Despite increasing efforts to use renewable electricity generation techniques in the last couple of decades, the world is still heavily reliant on traditional power generation techniques. This creates the need to make such systems cheaper and less pollutant through improvements to their efficiency. Increasing the efficiency and reliability of energy conversion systems, specially those based on combustion processes has been of interest for many years. However, material limitations have brought these systems to a stagnant condition.

A novel approach to help increase the efficiency of such systems is to closely monitor their operating conditions and therefore be able to increase …

Oxidation Of Niobium Silicides Obtained By Self-Propagating High-Temperature Synthesis, Frank Anthony Perez

Open Access Theses & Dissertations

Niobium silicide-based composites are promising materials for high-temperature structural applications, such as gas turbines. One attractive method for their fabrication is mechanically activated self-propagating high-temperature synThesis (MASHS). However, oxidation resistance of niobium silicides produced by MASHS has not been studied yet. In this present work, the oxidation of Nb/Nb5Si3 composites obtained by MASHS was investigated by using non-isothermal thermogravimetric analysis (TGA) and differential scanning analysis (DSC). Both techniques have shown that the oxidation starts at about 500 °C and the materials become fully oxidized at 750 â?? 800 °C. Model-based analysis of the TGA data has shown that the Avrami-Erofeev …

Mechanically Activated Combustion Synthesis Of Niobium Silicide Based Composites, Reina Trevino

Open Access Theses & Dissertations

Niobium silicide-based composites are promising materials for high-temperature structural applications, such as gas turbines, but their implementation is hindered by the lack of effective processing methods. Self-propagating high-temperature synThesis (SHS) is an attractive method for fabrication of advanced materials. However, it is difficult to perform SHS of niobium silicides because the melting point of Nb is higher than the combustion temperature, which greatly inhibits Nb-Si reaction. To ignite an Nb/Si mixture and obtain Nb5Si3, the desired phase in niobium silicides, either preheating or mechanical activation of the mixture is necessary. This problem becomes even more critical in the SHS of …

Accurate Replication Of An Ear Pinnae Geometry For Use In Acoustic Testing Of Spatial Cues And Sound Localization, Alejandra Belmont

Open Access Theses & Dissertations

Additive manufacturing (AM) enables freedom of design as well as fabrication of complex objects such as the human hear. In medical modeling there is a need for patient-specific customizable parts. The outer human ear consists of these main parts: the pinna, which naturally filters sound, and the ear canal, which is the point at which sound enters before being moved up to the tympanic membrane, otherwise known as the eardrum. In an attempt to accurately replicate ear models, the use of scanning and reverse engineering methods was used. A comparison of 3D laser scanning systems was performed to determine their …

Effect Of Flow Velocity And Geometry On The Signal From A Piezoelectric Flow Rate Sensor, Jad Gerges Aboud

Open Access Theses & Dissertations

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Development Of Recepticals And Joints For Embedded Electronic Components Inserted During Print Via Hybrid Thermoplastic-Based Additive Manufacturing, Leonardo Isaac Gutierrez Sierra

Open Access Theses & Dissertations

The use of hybrid additive manufacturing (AM) systems is a novel approach in the fabrication of multi-functional parts. 3D printed electronics are an example of multi-functional parts fabricated using the Foundry Multi3D System, a hybrid AM system. Previous research has demonstrated the capabilities of the system by manufacturing RF antennas and satellite panels with embedded electronics, to name a few. However, research to identify design clearances and establish a manufacturing process plan had not been performed. The purpose of this manuscript is to determine the correct clearances for foreign components to be inserted unto a partially printed substrate. Besides this …

Mechanical Performance Of Ebm Ti-6al-2sn-4zr-2mo Influenced By The Effects Of Different Hot Isostatic Pressing Treatments, Miguel Lopez

Open Access Theses & Dissertations

Electron Beam Melting (EBM) is an additive manufacturing process that presents a lower level of internal defects in comparison to Selective Laser Melting (SLM). Pairing Hot Isostatic Pressing (HIP) with Additive Manufactured metal parts, sub-surface voids can be eliminated through high pressure and temperature. This significantly improves fatigue life, impact toughness, creep, rupture strength, and tensile ductility. In this investigation, Ti-6Al-2Sn-4Zr-2Mo samples manufactured in the Arcam's Q20 system will be tested as per ASTM E8 Standard Test Methods for Tension Testing of Metallic Materials. Different variants of Hot Isostatic Pressing (HIP) treatments were analyzed and compared. Tensile testing was performed …

A High-Temperature Valve Design For A Solid Oxide Fuel Cell/Gas Turbine Hybrid System, Cynthia Morales

Open Access Theses & Dissertations

Systems containing high heat generation require thermal management, especially in a solid oxide fuel cell gas turbine (SOFC/GT) hybrid system. The startup of each system in a standalone configuration may be a trivial approach, but when coupled together, different dynamics are experienced. The SOFC/GT provide high theoretical efficiency due to the ability to recover the extra heat produced by the fuel cell (FC) to drive the gas turbine (GT). After recovering the energy recuperated in the GT, the exhaust gas heats the cathode inlet flow to the FC which is an advantage during nominal operation of the cycle but not …

Laser Diagnostics Of Compressible And High-Intensity Premixed Methane-Air Combustion Inside A Backward Facing Step Combustor Using High- Repetition Rate Ch-Plif And Piv, Md. Amzad Hossain

Open Access Theses & Dissertations

A novel high repetition rate (10 kHz) planar laser-induced fluorescence (PLIF) diagnostic technique was used for the flame front study. Premixed methane-air combustion was studied at different flow turbulence conditions (Re = 15000, 30000 and 64000; 12CFM, 25CFM and 50 CFM; 10m/s, 20 m/s and 40 m/s) and fuel loading (Փ =0.6 to 1.2). The study used an optically accessible backward-facing step high-speed combustor. Methane-air mixture was supplied to the combustor at atmospheric pressure and standard room temperature (T =25°C). CX-CH PLIF was used to detect the actual flame front structures. The flame dynamics were then correlated to the flow …

Design Of Experiments Analysis Of Powder Removal Methods For Ebm Manufactured Ti-6al-4v Parts, Luis Cesar Ramos Castañeda

Open Access Theses & Dissertations

Additive Manufacturing is a technology that allows the on-demand manufacturing of complex geometries that cannot be fabricated through traditional subtractive manufacturing methods. Powder Bed Fusion is one of the seven categories of Additive Manufacturing with two subcategories, the Laser Beam Melting and the Electron Beam Melting. Freedom of design, rapid prototyping, and customization are some of the benefits that this technology provides. Like any technology, there are limitations for each category and subcategory. The Electron Beam Melting uses the electron beam to pre-heat the powder bed, reducing the temperature difference between the build part and powder bed, causing the surrounding …