Mechanical Engineering Commons^™

Design And Data-Driven Identification Of A Quadruped Robot, Dakota Rufino

All Theses

The existence of nonlinearities and the lack of sufficient equations are fundamental challenges in modeling, analyzing, and controlling complex systems. However, recent developments revolutionizing the study of dynamical systems. An emerging method in nonlinear dynamical systems is the Koopman operator theory, which provides us with key advantages in performing the modeling, prediction, and control of nonlinear systems. The linear system representation allows us to leverage linear stability analysis. The first section of this thesis briefly covers the construction of a quadrupedal robot, a sufficiently complex nonlinear dynamical system, for the use of analyzing data-driven modeling techniques. The second section details …

Enhancing Microstructure, Composition Homogeneity, And Mechanical Properties In Laser Powder Bed Fused Metallic Alloys: Design, Fabrication, And Evaluation, Bahzad Farhang

Mechanical and Aerospace Engineering Dissertations - Archive

ABSTRACT: Over the past five decades, Nickel-based and Titanium-based alloys have become increasingly popular materials. As the manufacturing industry for these alloys has advanced, the demand for fabricating complex parts with enhanced mechanical properties at elevated temperatures has grown. Laser Powder Bed Fusion (LPBF), one of the most prevalent additive manufacturing techniques, has been employed successfully to produce these alloys. Nonetheless, there is still considerable effort being made to improve the microstructural, compositional, and mechanical properties of LPBF-processed components. In this study, we focused on adjusting the multi-scale microstructure and composition of LPBF-fabricated Nickel-based and Titanium-based alloys. The first objective …

Theoretical And Numerical Analysis Of Thermal Runaway Propagation In Li-Ion Battery Packs, Dhananjay Mishra

Mechanical and Aerospace Engineering Dissertations - Archive

Strategies to prevent or minimize propagation of thermal runaway in a pack of Li-ion cells are critically needed to ensure safe operation, storage and transportation. While significant literature already exists on thermal runaway simulations, several key questions of practical relevance have remained unaddressed. This work presents multi-mode heat transfer simulations to predict the onset and propagation of thermal runaway in a pack of cylindrical Li-ion cells. The impact of inter-cell gap and thermal properties of the interstitial material on onset and propagation of thermal runaway is studied. It is shown that high interstitial thermal conductivity promotes thermal runaway propagation. However, …

Steady State And Transient Analysis Of Heat Transfer In A Porous Fin With Radially Outwards Pressure-Driven Flow, Muhammad Mehdi Abbas

Mechanical and Aerospace Engineering Theses - Archive

Thermal management and energy storage problems often utilize extended surfaces, also known as fins for enhanced heat transfer. Today fins are used in a wide range of devices including but not limited to microelectronic components and large heat exchanger. Traditional fins as well as porous fins with flow orthogonal to fin direction have been subject of past research. There is very few academic literature available on porous fins with pressure driven flow along fin direction. While thermal conduction is usually the dominant mode of heat transfer in a solid fin, the use of porous fins that include advective thermal transport …

Development Of Vortex Box (Vbox) And Vortex Tip (Vtip) Filament Free-Wake Rotor Models, Casey Will Matsler

Mechanical and Aerospace Engineering Theses - Archive

Rotor models span from simple static and first order expressions to high fidelity, numerical computations and across the spectrum each model is good for different purposes. The use of models has improved with time and technological capability but choosing the right model for the task is important. A survey of rotor models is performed to identify a rotor model flexible enough for providing high to moderately high-fidelity results without significantly sacrificing computational time. The model chosen is intended to be for general purposes and applicable across a wide range of operating conditions. From the survey, a blade element rotor model …

Evaluation Of Solder Alloys For Bga Package: A Comparative Reliability Study Using Ansys Computational Analysis, Yashvanth Muthegowda

Mechanical and Aerospace Engineering Theses - Archive

Temperature cycling failure of solder joints in Ball Grid Array (BGA) packages has become a critical issue in electronic manufacturing. This thesis specifically characterizes three different lead-free solder alloys (Pure Indium, SAC-387, and SAC-Q) in BGA solder joints using two different printed circuit board (PCB) thicknesses (1mm and 0.7 mm). The analysis considers the non-uniform temperature distribution caused by the main heat source, the die, and the resulting deformation of the package due to the mismatch in the coefficient of thermal expansion (CTE) between components used in BGA. Finite element (FE) models are created in ANSYS mechanical package environment to …

Advancement Of An Inhouse Aerospace Vehicle Design Synthesis System Through The Introduction Of A Novel Database-Knowledgebase System And By Improving The Geometry And Aerothermodynamic Disciplinary Processes, Samuel Atchison

Mechanical and Aerospace Engineering Theses - Archive

Throughout the years of aerospace vehicle design, the process in which a vehicle is designed has drastically improved from being primarily developed through trial and error, to using sophisticated synthesis systems. While the trial-and-error process had its uses with providing the fundamental knowledge of how aircraft behave and can be designed, the increase in knowledge and technology allowed the possibility of more vehicle configurations to be explored without the need to build each one. This increase should have led to a revolution of vehicle designs, and while there have been some novel ones, it seems that the general design of …

Numerical Modeling Of Damper Configuration And Arrangements For Analysing Thermal Stratification In Modular Air Handling Units, Rohit Antony Raymonds

Mechanical and Aerospace Engineering Theses - Archive

Although air handling units are well established and maturated there are opportunities to optimize and improve the overall thermal and flow performance to reduce the carbon footprint of an air-cooled data center. Airside economization (ASE) arrangement to use cold outdoor air to minimize mechanical cooling energy was substantial progress in minimizing the power usage effectiveness (PUE) for data centers. ASE is an arrangement of ducts and dampers with the necessary controls to meet the cooling requirements. Dampers play a significant role in regulating the mass flow rate of the air and in mixing the two air streams: cold outdoor air, …

Effects Of Metal Organic Frameworks In Polyether Block Amide Elastomer, Joe Alex

Mechanical and Aerospace Engineering Theses - Archive

Metal-organic frameworks (MOFs) are highly porous materials that find extensive applications in gas absorption and separation in recent years. These hybrid materials can be designed with specific pore sizes and voids to selectively filter gases. PEBAX (MV 1074) is a commercially available polyether block amide copolymer generally used in gas separation applications. In this study, we characterize two different MOFs by means of a dispersion study and create a medium for them to be evenly dispersed into the aforementioned copolymer matrix. Polymer composite fibers are extruded using a twin-screw extruder and a winding unit at pre-determined parameters for winding speed …

Impact Of Immersion Cooling On Thermo-Mechanical Properties Of Non-Halogenated Core, Mohan Sai Ramalingam

Mechanical and Aerospace Engineering Theses - Archive

The rise in demand for modern high-power systems, which require fast processing and frequent data storage, has resulted in an exceptional and unprecedented increase in power density and heat generation within data centers. This eventually led to the need for advanced cooling techniques that can address the challenges of managing the heat produced by the data centers. As per Moore's law and Dennard's scaling, the power densities of chips and the heat flux generated by servers are continuously increasing. [1] As a result, the dissipation of heat at the chip level has also increased, posing a significant challenge for thermal …

Comparative Design Space For Bistable Composites: An Integrated Framework Of Optimization, Finite Element Analysis, And Experimental Testing, Jonathan Bolanos

All Theses

Bistable composites are a class of advanced materials that can actuate between two stable shapes, making them attractive for a wide range of engineering applications. However, designing these composites to achieve optimal performance remains a challenging task. To address the challenge, this research develops an integrated framework that combines a genetic algorithm optimization technique, finite element analysis in Abaqus, and experimental testing to explore the design comparative space for square bistable composites composed of DA 409 carbon fibers. This leads to the study of generating an optimization algorithm to account for the relationship between the chances of a successful maximum …

Laser Stabilization Through Optical Turbulence, Liam Vanderschaaf

All Theses

Laser jitter presents a significant issue in the fields of laser communication and sensing. There are two main categories of positional noise in regards to the instantaneous centroid of a laser propagating over long distances: jitter resulting from optical turbulence and jitter resulting from mechanical vibrations. Optical turbulence was generated using Clemson University’s Variable Turbulence Generator (VTG). The VTG is capable of creating a desired level of optical turbulence that is comparable to atmospheric conditions with fried parameters greater than 0.3 cm. A gaussian laser was transmitted through the VTG and a system of Fast Steering Mirrors and Position Sensing …

Compliant Robot Manipulator For Transurethral Diagnosis, Samson A. Adejokun

Mechanical and Aerospace Engineering Dissertations - Archive

ABSTRACT: Minimally invasive procedures employ continuum manipulators, however, the internal human anatomy presents challenges relating to size, dexterity, and workspace for these manipulators. This research presents modeling, kinematic analysis, limited prototyping, and characterization of a micro-robotic manipulator to assess viscoelastic tissue properties of the bladder through transurethral palpation towards the diagnosis of bladder dysfunction, urinary incontinence, and early-stage bladder cancer. The proposed micro-robot consists of two subsystems; a unique 4mm outer diameter tendon-driven continuum segment from assembled “vertebrae” components with male and female snap-in features for joint assembly, an elastic tube encompassing each joint for controlled compliance and structural integrity …

Development Of Femtosecond Laser Electronic Excitation Tagging (Fleet) And Femtosecond Two-Photon Absorption Laser Induced Fluorescence (Fs-Talif) Diagnostics For Species Number Density And Velocity Measurements In Arc-Jet Flows, Daniel William Palmquist

Mechanical and Aerospace Engineering Dissertations - Archive

ABSTRACT: Arc-jet flows are the only ground-test facilities that can recreate hypersonic high-enthalpy flight conditions for long durations. Characterizing these complex flow regimes, generally under thermo-chemical non-equilibrium, is crucial to establishing a relationship between the ground-test environment and flight conditions. This work presents the development of two innovative and world’s first successful application of advanced non-intrusive laser-based diagnostic techniques for characterizing the 1.6 MW ONR-UTA Arc-Heated Wind Tunnel, Leste’s plasma flow. The arc-jet flow represents a unique challenge for the application of laser-based diagnostics due to the highly emitting background across a wide spectral range. Femtosecond Laser Electronic Excitation Tagging …

Fatigue Performance Modeling In Advanced Out-Of-Autoclave Composites For Aerospace Applications, Grayson Reid Curry

Mechanical and Aerospace Engineering Theses - Archive

Increased application of composite materials in the military and civil applications renewed the interest to development of high-fidelity methodologies for predicting their performance characteristics. Besides the traditional autoclave processed structural composites such as IM7/8552 and IM7/977-3 widely used on various platforms, novel materials such IM7/5320-1 suitable for Out-of-Autoclave (OoA) cure became of interest. Static and fatigue performance prediction of Open-Hole quasi-isotropic laminates made from IM7/5320-1 was performed in this work by using the Finite Element Analysis software BSAM. Progressive failure simulation including delaminations, matrix cracks and fiber failure was performed. Regularized eXtended Finite Element Methods (RXFEM) was used for mesh …

Mesoscale Modeling And Machine Learning Studies Of Grain Boundary Segregation In Metallic Alloys, Malek Alkayyali

All Dissertations

Nearly all structural and functional materials are polycrystalline alloys; they are composed of differently oriented crystalline grains that are joined at internal interfaces termed grain boundaries (GBs). It is well accepted that GB dynamics play a critical role in many phenomena during materials processing or under operating environments. Of particular interest are GB migration and grain growth processes, as they influence many crystal-size dependent properties, such as mechanical strength and electrical conductivity.

In metallic alloys, GBs offer a plethora of preferential atomic sites for alloying elements to occupy. Indeed, recent experimental studies employing in-situ microscopy revealed strong GB solute segregation …

Electrochemical Investigation Of Copperzirconium Based Metallic Glass Cu₅₁Zr₃₀Hf₁₄Ag₅, Tamim Mohammad Ahmad

Theses

This thesis is concerned with the electrochemical investigation of the copper-zirconium

based metallic glass Cu₅₁Zr₃₀Hf₁₄Ag₅. Studying the corrosion behavior of the novel melt-spun metallic glass ribbons contributes to further research on the possibility of building future bio-implants. The objectives of this thesis are to synthesize the metallic glass ribbons which are free from cytotoxic elements using melt spinning technique, verify their amorphous nature using X-ray diffraction method, study the corrosion behavior using Potentiodynamic polarization and Electrochemical Impedance Spectroscopy in different acidic, neutral and basic solutions, and finally examine the surface morphology of …

Convexity Applications In Single And Multi-Agent Control, Olli Nikodeemus Jansson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The focus of this dissertation is in the application of convexity for control problems; specifically, single-agent problems with linear or nonlinear dynamics and multi-agent problems with linear dynamics. A mixture of convex and non-convex constraints for optimal control problems is also considered. The main contributions of this dissertation include: 1) a convexification of single-agent problems with linear dynamics and annular control constraint, 2) a technique for controlling bounded nonlinear single-agent systems, and 3) a technique for solving multi-agent pursuit-evasion games with linear dynamics and convex control and state constraints. The first result shows that for annularly constrained linear systems, controllability …

E-Cadherin Force Transmission And Stiffness Sensing, Mazen Mezher

Mechanical & Aerospace Engineering Theses & Dissertations

E-cadherin is the chief mediator of cell-cell adhesion between epithelial cells and is a known mechanosensor. Force transmission and stiffness sensing are two crucial aspects of E-cadherin mechanobiology.

E-cadherin has an extracellular adhesive region, a transmembrane region and an intracellular region that binds to adhesion-associated proteins. Here, we assessed how different factors affect the level of force transmission (i) from inside the cell such as adhesion-associated proteins, (ii) on the cell membrane, such as growth factor receptors and (iii) outside the cell, such as different binding partners in adhesion. To study the level of force transmission inside the cell, we …

Fusion Bonding Behavior Of 3d Printed Pa6/Cf Composites Via Post Fabrication Compaction, Gonzalo Fernandez Mediavilla

Mechanical & Aerospace Engineering Theses & Dissertations

Additive manufacturing (AM) is becoming a robust production technology for aerospace, healthcare, and construction industries among others. Fused Deposition Modelling (FDM) is one of the methods most used to 3D print products. FDM has limitation due to interlayer adhesion and restriction imposed by the printing direction. Specially with AM composites, as reinforced nylon PA6 with short fibers, parts show more strength along the direction of the filament due to the alignment of the carbon fibers, but weaker in other directions. The proposed method to solve this issue is to print parts separately and join them together by fusion bonding. PA6/CF …

Fabrication Of Solid Oxide Fuel Cell Components Using Stereolithography 3d Printing, Hannah Dyer

Mechanical & Aerospace Engineering Theses & Dissertations

Transitioning from fossil fuel supplied energy to renewable technology must meet cost efficient parameters throughout the manufacturing process while possessing the characteristics of a functioning and reliable power source. With a significant demand in renewable energy products, developmental techniques require adaptive approaches and procedures for novel materials in the manufacturing phase. This report proposes how a solid oxide fuel cell (SOFC), a renewable energy system, can employ additive manufacturing for directly 3D printing its components by utilizing stereolithography (SLA) 3D printing techniques. Fabrication of the printed components from the mixtures were first mixed with varying concentrations of ceramic powder and …

Using Immersive Technology To Improve Mechanical Design: Use Cases, A Review Of Current Technology, And An Experiment In Requirement Elicitation In Virtual Reality, William Hawthorne

All Theses

There has been a growing trend in the use of immersive technologies within engineering design. This research is focused on understanding how Virtual Reality (VR) technologies support design reviews. Modern tools including virtual reality hardware and software were tested for current capabilities and challenges. In a review of literature, two key gaps are identified: the rapid advancements of VR and AR technology and limited formal studies to determine the costs and benefits of immersive technology within engineering design reviews. This research has resulted in three key outcomes. First, use cases of immersive reality technologies are identified, through the lens of …

Point Heat Source Correlation To Microstructural Evolution In Advanced Manufacturing, Mark Anderson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Although there are different ways that advanced manufacturing can be performed, the use of single-point heat sources has become the standard to control a final product’s properties. It is imperative to understand how the heat source used in the different advanced manufacturing processes affect the microstructure of interest. The intimate relationship between the heat source and microstructure allows for controlling and tailoring a part’s properties. Utilizing different microstructural analysis, the cross-correlation of various point heat sources to developed microstructure was conducted in this dissertation.

Laser powder bed fusion allows for unique print-to-part protocols, but the dynamics of the process makes …

Trace Dna Detection Using Diamond Dye: A Recovery Technique To Yield More Dna, Leah Davis

Master's Theses

This study aspires to find a new screening approach to trace DNA recovery techniques to yield a higher quantity of trace DNA from larger items of evidence. It takes the path of visualizing trace DNA on items of evidence with potential DNA so analysts can swab a more localized area rather than attempting to recover trace DNA through the general swabbing technique currently used for trace DNA recovery. The first and second parts consisted of observing trace DNA interaction with Diamond Dye on porous and non-porous surfaces.

The third part involved applying the Diamond Dye solution by spraying it onto …

Engineered Material Systems For Mimicking Tissue And Disease, Margrethe Ruding

McKelvey School of Engineering Graduate Student Theses & Dissertations

This thesis comprises two studies involving design and application of soft material systems. The goal of the first study was to design, fabricate, and characterize hydrogel lattice structures with consistent, controllable, anisotropic mechanical properties. Lattices, based on four types of unit cells (cubic, diamond, vintile, and Weaire-Phelan), were printed using stereolithography (SLA) of polyethylene glycol diacrylate (PEGDA). In order to create structural anisotropy in the lattices, unit cell design files were scaled in one direction by a factor of two in each layer and then printed. The mechanical properties of the scaled lattices were measured in shear and compression and …

Characterizing Energy Dissipation Of Shallow-Water Wave Breaking In A Storm Surge, Hunter Boswell, Guirong Grace Yan, Wouter Mostert

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

While understanding breaking waves is crucial for the development of parametrizations used in ocean wave modeling for both deep and shallow water, the complete process of wave breaking is not well understood. Here we present direct numerical simulations of two-dimensional solitary waves that shoal and break on a uniform beach in shallow water, with the presence of storm surge represented by an inshore region. The storm surge depth, beach slope, and wave amplitude are varied to study the dependence of energy dissipation in the breaker on wave and bathymetric parameters. We classify wave breaker types and find a separation between …

Cycle Time Reduction In Additive Manufacturing Using Peltier Thermoelectric Cooling Devices, Trevor Carlton

Honors College Theses

Thermoelectric cooling and the Peltier effect were discovered in 1834, over 188 years ago. Additionally, the first iterations of additive manufacturing (i.e., 3D printing) began in the early 1980s, more than 40 years ago. Despite these technologies’ age and years of advancements, the application of Peltier cooling-based devices in additive manufacturing has not yet been realized. These devices can be used for the active thermal management of print beds in 3D printers. Developing a mechanism to heat and cool a print bed can reduce the cycle time to manufacture a part. In 3D printing, waiting for the heated bed to …

Probabilistic Machine Learning For Battery State Of Health Prognostics, Charli Zaretsky

Honors Scholar Theses

The ability to understand and predict the state of health (SOH) of lithium-ion batteries is an integral component of their widespread commercial use. There are various methods through which SOH can be analyzed and predicted, and this paper discusses these different methods, and the strengths and weaknesses of each. This paper also details an analysis of lithium-ion battery SOH through two data-driven machine learning methods: XGBoost and Gaussian process regression. A comparison is made between each method’s accuracy in predicting next-cycle discharge capacity using electrochemical impedance spectroscopy (EIS) readings and battery charge and discharge rates, from a dataset given in …

Self-Assembly Of Exfoliated Graphene Flakes As Anticorrosive Coatings For Additive Manufactured Steels, Kaleb Hood, Wen Qian, Savannah Krupa, Annie Dao, Sarah Ahmed, Samuel Olson, Jun Jiao, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

This study demonstrates the feasibility of using liquid exfoliation of expandable graphite into multilayer exfoliated graphene flakes (EGFs) to form a self-assembled thin film on an air–water interface. The film can coat the surface of additive manufactured (AM) steel substrates to enhance surface properties, specifically AM 316 stainless-steel (AM316), AM 8620 steel (AM8620), and samples of the same alloys made by conventional manufacturing (CM) processes. Liquid exfoliation offers a high yield route for an EGF coating that can cover up to 95% of the sample surface with a single application. The thin, flexible EGFs can coat a rough AM metal …

Mechanical And Thermal Performance Of Additively Manufactured Digital Materials, Layth Muayyad Ahmad

Mechanical and Aerospace Engineering Theses - Archive

Over the past decades, additive manufacturing has become a critical material processing tool. All ranges of materials including polymers, composites, metals, and ceramics can be used to fabricate structures with complex geometries that are nearly impossible to build using conventional fabrication process. Recently, additive manufacturing methods to build polymeric structures have been advanced significantly. In particular, the emergence of multi-material printers has made it possible to seamlessly print hybrid and digital materials where materials components and compositions are digitally varied to construct fully tailored material system. In this work, using a commercially available polyjet printer (Stratasys J850 Prime 3D printer), …