Mechanical Engineering Commons^™

Numerical Simulation Of Electroosmotic Flow Of Viscoelastic Fluid In Microchannel, Jianyu Ji

Mechanical & Aerospace Engineering Theses & Dissertations

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which often involve the use of viscoelastic non-Newtonian fluids. Due to the existence of the elastic effect, the viscoelastic EOF develops into chaotic flow under extremely low Reynolds numbers, which is known as elastic turbulence. The mechanism of elastic turbulence in electroosmotic flow remains unclear. Numerical simulation plays an important role in understanding the mechanisms of elastic turbulence. This dissertation is aimed to study the EOF of viscoelastic fluids in constriction microchannels under various direct current (DC) and alternating current (AC) electric fields. First, the EOF …

Supporting Us Army Next-Generation Ground Vehicle Simulation Modeling Using An Integrated Ontology Suite, Edward Louis

All Theses

The development of the US Army’s next-generation of ground vehicle systems is supported by simulations that predict vehicle performance and inform engineering design choices in the design and acquisition process. In this paper, we describe the development of an Integrated Ontology Suite to support modeling and simulation of next generation military ground vehicles. The ontology suite is intended to address model reuse challenges and increase the shared understanding of ground vehicle system simulations. It is intended to function in a Model Library structure that stores, documents, assembles, and executes vehicle simulations. The ontology suite consists of four domain ontologies: Vehicle …

Effects Of Polymer Side-Group Size On Interfacial Mechanics Of Graphene-Polymer Nanocomposites, Grace Brokaw

All Theses

Graphene-reinforced polymer nanocomposites possess excellent mechanical, thermal, and electrical properties, which make them promising candidates for various applications. Favorable interfacial interactions and mechanics between graphene sheets and polymer matrices are often essential to achieve superior mechanical properties. Nevertheless, it remains largely elusive how molecular features of polymer systems, particularly the side-group size of polymer chains, affect the interfacial mechanics between graphene sheets and polymer matrices, primarily due to challenges in well controlling these features in experiments. On the other hand, exploring their roles in the mechanical properties of graphene-polymer nanocomposites is very expensive to study with all-atomistic molecular dynamics (MD) …

Utilizing Systematic Design And Shape Memory Alloys To Enhance Actuation Of Modular High-Frequency Origami Robots, Jessica M. Den Haese

All Theses

Shape memory alloys (SMAs) describe a group of smart metallic materials that can be deformed by external magnetic, thermal, or mechanical influence and then returned to a predetermined shape through the cycling of temperature or stress. They have several advantages, such as having excellent mechanical properties, being low cost, and being easily manufactured, while also providing a compact size, completely silent operation, high work density, and requiring less maintenance over time. SMAs can undergo sold-to-solid phase transformations, and it is because of these phase transformations that they can experience shape memory effect (SME); or the ability to recover from a …

An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent, Graham Lancaster

All Theses

This research considers the problem of using bistable laminates as a mechanical deterrent to the impending impact of a particle. The structure will be controlled through an algorithm that will utilize piezoelectric devices to activate them in unison with the bistable laminate to successfully deter. A novel experimental setup will be constructed to ensure that the bistable laminate stays fixed when acting as a mechanical deterrent. Piezoelectricity is the main driving force of the bistable laminate to morph and this study will use a Macro Fiber Composite (MFC) actuator that contains piezoelectric ceramic rods in a patch to transfer electrical …

High Throughput And Highly Controllable Methods For In Vitro Intracellular Delivery, Justin Brooks, Grayson Minnick, Prithvijit Mukherjee, Arian Jaberi, Lingqian Chang, Horacio D. Espinosa, Ruiguo Yang

Department of Mechanical and Materials Engineering: Faculty Publications

In vitro and ex vivo intracellular delivery methods hold the key for releasing the full potential of tissue engineering, drug development, and many other applications. In recent years, there has been significant progress in the design and implementation of intracellular delivery systems capable of delivery at the same scale as viral transfection and bulk electroporation but offering fewer adverse outcomes. This review strives to examine a variety of methods for in vitro and ex vivo intracellular delivery such as flow-through microfluidics, engineered substrates, and automated probe-based systems from the perspective of throughput and control. Special attention is paid to a …

Measurement Of Low-Speed Impinging Jet Structure Using Temperature Sensitive Paint, Arthur Dean Woodworth

Masters Theses

Temperature sensitive paint (TSP) is used to analyze surface flow structures driven by a jet impinging on a heated steel sheet. Temperature and Nusselt number images are calculated from CCD images of the TSP surface. TSP calibration is discussed. Skin friction data is obtained from the temperature images.

Data is collected for metal and 3D-printed plastic nozzles of varying shape and size at one or two jet airspeeds depending on the nozzle. For the circular nozzles, data is collected for four Reynolds numbers at impinging angles of 90, 70, and 50 degrees. For the elliptical nozzles and the star-shaped nozzle, …

Design And Optimization Of High-Power Density Permanent Magnet Motor With Integrated Cooling For Aircraft Propulsion, Aravindakshan Thirumalai Ananthanpillai

Theses and Dissertations

There is a critical need for the electrification of transportation systems. While power density required for ground-based vehicles can, to some extent, be met by current off-the-shelf motors and generators, aircrafts require significant improvements both in terms of power density and efficiency. The concept relies on the tight integration of a high-power density dual-rotor permanent magnet motor, high power density SiC power converters, and a shared closed loop cooling system rejecting the heat in the propulsion ducted fan air stream. The motor is based on a dual-rotor configuration using permanent magnets forming ideal Halbach arrays allowing for high magnetic loading …

Thermal Design And Energy Analysis Of A Greenhouse In Microgravity Conditions, Nivedha Karigiri Madhusudhan

Theses and Dissertations

The recent progress in commercial space flights and prospects for interplanetary space missions has attracted more attention towards developing sustainable built environments in microgravity conditions. An important factor in establishing a sustainable living condition for outer space applications is the ability to produce food. The thermal design considerations in a greenhouse have a major impact on the survival, water efficiency, quantity, and quality of plants produced. The extremely low environmental temperatures necessitate the use of heaters which do consume energy. Given the scarcity of energy access, it is important to achieve proper thermal conditions with the lowest possible energy requirements. …

Dynamic Surface Tension Of Surfactants Through Separation Of Diffusion And Dilation Effects, Brandon Ortiz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Surfactants are biphilic monomers that adsorb to interfaces and have the ability to reduce interfacial tension. From this reduction in interfacial tension, surfactants are able to function as emulsifiers, detergents, and wetting agents among a variety of other things. Despite their ubiquity surfactants and surfactant behaviors, in particular those in highly dynamic environments, are not yet well characterized. In these environments, surfactants undergo significant distortions to droplet, bubble, and foam geometries which induce changes to the surface tension. This establishes a need to understand how surfactants respond to distortions of geometry through diffusion and dilational effects. To address this need, …

Mechanoelectrical Behavior In Polyvinyl Chloride (Pvc) Based Soft Polymer Gel Smart Sensors For Soft Robotic Applications, Justin Neubauer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyvinyl chloride (PVC) gels are a class of electroactive polymer that contain a PVC-based polymeric lattice and various amounts of plasticizer. PVC and plasticizer are industrially available and are commonly used in a wide range of applications including cable insulation, flexible hosing, and healthcare equipment. There are many plasticizer types available, some being extremely biocompatible with implementations in food-safe applications and even food additives for human consumption. Plasticizer weakly bonds to the long polymerized chains of the polymer lattice decreasing the modulus of the composite material. By adding excessive amounts of plasticizer, the bonding sites of these long carbon chains …

Mechanics Modeling Of Non-Rigid Origami: From Qualitative To Quantitative Accuracy, Jiayue Tao

All Dissertations

Origami, the ancient art of paper folding, has recently evolved into a design and fabrication framework for various engineering systems at vastly different scales: from large-scale deployable airframes to mesoscale biomedical devices to small-scale DNA machines. The increasingly diverse applications of origami require a better understanding of the fundamental mechanics and dynamics induced by folding. Therefore, formulating a high-fidelity simulation model for origami is crucial, especially when large amplitude deformation/rotation exists during folding.

The currently available origami simulation models can be categorized into three branches: rigid-facet models, bar-hinge models, and finite element models. The first branch of models assumes that …

Multiple Heat Exchanger Cooling System For Automotive Applications – Design, Mathematical Modeling, And Experimental Observations, Zaker Syed

All Dissertations

The design of the automotive cooling systems has slowly evolved from engine-driven mechanical to computer-controlled electro-mechanical components. With the addition of computer-controlled variable speed actuators, cooling system architectures have been updated to maximize performance and efficiency. By switching from one large radiator to multiple smaller radiators with individual flow control valves, the heat rejection requirements may be precisely adjusted. The combination of computer regulated thermal management system should reduce power consumption while satisfying temperature control objectives. This research focuses on developing and analyzing a multi-radiator system architecture for implementation in ground transportation applications. The premise is to use a single …

Infusing Kirigami Principles Into Design Of Mechanical Properties, Hesameddin Khosravi

All Dissertations

The emergence of mechanical metamaterials — which derive their properties primarily from the underlying architecture rather than the constituent material — has unleashed a new era of material design and functionalities. To fully materialize the promising potentials of metamaterials, it is crucial to develop versatile, scalable, and easy-to-fabricate methods that can both generate and tailor the underlying periodic architecture. To this end, we propose the use of kirigami — a popular recreational art of cutting and manipulating paper — as a platform to create periodicity and super-stretchability. Kirigami has become a design and fabrication framework for constructing metamaterials, robotic tools, …

Development And Characterization Of Forcespinning® Mesquite Gum Nanofibers, Cristobal Rodriguez, Victoria Padilla, Karen Lozano, Alexa Villarreal, Luis A. Materon, Robert Gilkerson

Mechanical Engineering Faculty Publications

In this study, nanofibers incorporating Prosopis glandulosa mesquite gum (MG) exudate combined with biodegradable polymers, pullulan (PL) and chitosan (CH), were produced via the Forcespinning® technique. The nonwoven composite membranes were characterized via scanning electron microscopy followed by thermogravimetric and Fourier-transform infrared spectroscopy analysis. MG nanofiber composites comprised long, continuous fibers with an average fiber diameter of 523 ± 180 nm and 760 ± 225 nm for 18.1 and 28 wt% of MG, respectively. These composite membranes were water-stable after crosslinking via heat treatment with a ∼3 % water absorption capacity, and demonstrated a thermal capability with an increasing …

Review Of Vegetable Nanolubricants For Tribological Applications, Laura Peña-Parás, Martha Rodríguez-Villalobos, Demófilo Maldonado-Cortés, José Andrés González, Ricardo De Jesús Durán, Javier A. Ortega

Mechanical Engineering Faculty Publications

About 40 million tons of lubricants are used every year for various industry purposes and applications, where most of them are petroleum based oils. These oils are difficult and expensive to dispose of, have low biodegradability and are contamination risks. Recent efforts have been focused on reducing the environmental impact of petroleum based lubricants through the use of vegetable oils since they are biodegradable and have good lubricity. A drawback of vegetable oils is their poor thermal stability and oxidation, which causes them to decrease their properties at higher loads. Nanoparticle (NP) additives have been explored for improving the tribological …

Parametric Modeling Of Biomimetic Sharkskin For Wire Edm For Drag Reduction And Hydrophobicity, Joel Maxwell

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

This research sets out to demonstrate the viability of parametric modeling for biomimetic sharkskin in the effort to reduce drag and create a self-cleaning surface. Multiple designs were created to be machined by Wire EDM on stainless steel and titanium and were comparatively tested. Limitations of current manufacturing processes to economically produce naturally occurring structures such as sharkskin, emphasize the need to be able to calculate the most accurate design for a given manufacturing process. By designing a simplified but parametrically consistent model compared to an accurately depicted 3D model of sharkskin, the textured samples produced can be further tested …

Prediction Of Meltpool Depth In Laser Powder Bed Fusion Using In-Process Sensor Data, Part-Level Thermal Simulations, And Machine Learning, Grant King

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

The goal of this thesis is the prevention of flaw formation in laser powder bed fusion additive manufacturing process. As a step towards this goal, the objective of this work is to predict meltpool depth as a function of in-process sensor data, part-level thermal simulations, and machine learning. As motivated in NASA's Marshall Space Flight Center specification 3716, prediction of meltpool depth is important because: (1) it can serve as a surrogate to estimate process status without the need for expensive post-process characterization, and (2) the meltpool depth provides an avenue for rapid qualification of microstructure evolution. To achieve the …

The Effect Of Zonation, Biofouling, And Corrosion Products On Cathodic Protection Design For Offshore Monopiles, Caglar Erdogan

Theses and Dissertations

Cathodic protection (CP) is required to prevent corrosion of the submerged steel for offshore wind monopile foundations in the marine environment. The design of these systems depends on the environmental conditions, including temperature, salinity, pH, dissolved oxygen, depth, micro- and macro-organisms, and water flow rates. The standards utilized to design cathodic protection systems consider only some of these conditions. This research identified the gaps in knowledge for the design of corrosion prevention systems for offshore wind monopile foundations and investigated the changes in cathodic current densities due to macro-galvanic cells, fouling communities and corrosion products established on uncoated vertical steel …

Assembly Of Ceramic Particles In Aqueous Suspensions Induced By High-Frequency Ac Electric Field, James E. John Iv

Mechanical & Aerospace Engineering Theses & Dissertations

Ceramic materials processed using colloidal methods have been the focus of a great deal of research aimed at tailoring the final structure and microstructure of the finished ceramic sample. To this end, various external field effects have been investigated to modify the suspension microstructure without manipulating the ceramic particles directly. In a previous work in the field of ice templating it has been shown that AC electric fields are able to produce microstructural changes in ice templated ceramics that have significantly improved the final mechanical properties. However, the mechanisms for this process are still not well understood in ceramics.

To …

Tympanostomy Tubes In Children: A Fem Study Of Adverse Effects, Manuel Nicolas Jaramillo Bucheli

Theses and Dissertations

Background: The current study investigates if tympanic (myringotomy) tubes affect hearing by comparing the harmonic displacement response to sound excitation within the hearing frequency range for healthy vs. surgically-treated pediatric tympanic membranes. The use of ear myringotomy tubes has proven an effective method for combating recurrent ear infections in infants and children. These tubes are placed in the tympanic membrane through an incision and connect the middle ear to the external ear, thereby allowing fluid drainage and middle-ear ventilation. While this treatment has been proven beneficial in alleviating urgent pus accumulation in the middle ear, recent research shows that it …

Multi-Fidelity Predictions For Control Allocation On The Nasa Ikhana Research Aircraft To Minimize Drag, Justice T. Schoenfeld

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Optimal control settings (camber scheduling) can be used by aircraft to minimize drag at various operating conditions during flight. In this work, camber schedules for minimum drag on the NASA Ikhana are obtained over a range of lift coefficients. A modern numerical lifting-line algorithm is used to predict the lift and drag of the aircraft as a function of operating condition and wing section shape (airfoil camber). The SLSQP optimization algorithm is used to solve for the camber schedule that minimizes drag for a given operating condition. The process is repeated, varying the number of control sections to evaluate the …

Linearized Rigid-Body Static And Dynamic Stability Of An Aircraft With A Bio-Inspired Rotating Empennage, Austin J. Kohler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The United States Air Force (USAF) will likely seek to remove the vertical tail of next-generation fighter aircraft. This work seeks to characterize the static and dynamic stability and handling qualities of a vertical-tailless aircraft concept that would satisfy the USAF’s goal. This concept aircraft, one modified with a Bio-Inspired Rotating Empennage (BIRE), does not have a vertical tail, and is instead capable of rotating the horizontal tail about the fuselage axis for maneuvering. The dynamic characteristics of the BIRE-modified aircraft are compared to a baseline unmodified aircraft, similar to the F16, with a traditional vertical tail. Linearized aerodynamic models …

Developing A Methane Detector For Aerospace Applications, Michael A. Kirk

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Greenhouse gasses in the atmosphere are raising the global temperature and causing adverse side effects. Of these greenhouse gasses, methane is one of the most impactful, second only to carbon dioxide. One of the methods for determining the concentration of methane in the atmosphere is taking images of the earth from space. The purpose of this project is to further a new imaging technology for detecting methane leaks called FINIS (Filter Incidence Narrow-band Infrared Spectrometer), thus improving our capability to detect and locate methane leaks and reduce greenhouse gas emissions. FINIS has been developed in various stages since 2018 and …

Solar Chimney Power Plants: A Mini Review, Ahmed Reda, Waseem Salah, Ahmed Suwailem, Shehab Eldin Ahmed, Omar Lasheen, Amira Elkodama, Moustafa R. Shousha, Amr Ismaiel, Anas A. Rahman

Future Engineering Journal

The main investigations of a novel solar thermal application known as SCPP are summarized in this paper. It is a method of producing electricity from solar energy that relies on the fact that air rises when it is heated. An adequate position within a tall chimney can be utilized to position a turbine to turn it, creating an updraft that can be used to generate power. This system's specifications, design, construction, and use are all covered in the paper along with experimental and analytical research related to it. It also emphasizes the development and execution of SCPP programs.

Low-Cost, Low-Weight Test Rig Design For A Laboratory-Scale Twin Rotor Wind Turbine, Ahmed Ayoub, Ahmed Elzeedy, Mahmoud Elkordy, Eslam Ayad, Mohamed Waleed, Amira Elkodama, Amr Ismaiel

Future Engineering Journal

Multi-Rotor Wind Turbine (MRWT) has been proven advantageous over Single-Rotor Wind Turbine (SRWT) in many aspects. In order to study the performance of MRWT over SRWT, this work presents a low-cost and low-weight design for a test rig for laboratory-scale wind turbine configurations. The configurations under study are a single-rotor, and a twin-rotor of the same size with a diameter of 30 cm. Aerodynamic loads have been calculated using the Blade Element Momentum (BEM) method, then the loads were used for stress analysis over the test rig proposed. The test rig is designed on Solidworks and the aerodynamic and inertial …

Performance Comparison Of Several Control Algorithms For Tracking Control Of Pantograph Mechanism, Laylaa Mahmoud Eng, Mohamed Shamseldin Dr, Mohamed Sallam Dr, Abdelghany Mohamed Prof

Future Engineering Journal

A sort of parallel manipulator known as a pantograph robot mechanism was created primarily for industrial requests that required high precision and satisfied speed. While tracking a chosen trajectory profile requires a powerful controller. Because it has four active robot links and one robot passive link in place of just two links like the open chain does, it can carry more loads than the open chain robot mechanism while maintaining accuracy and stability. The calculated model for a closed chain pantograph robot mechanism presented in this paper takes into account the boundary conditions. For the purpose of simulating the dynamics …

Relative Rate Observer Self-Tuning Of Fuzzy Pid Virtual Inertia Control For An Islanded Microgrid, Ahmed H. Mohamed, Helmy M. El Zoghby, Mohiy Bahgat, A. M. Abdel Ghany

Future Engineering Journal

Expanding the usage of renewable energy in islanded microgrids leads to a reduction in its total inertia. Low inertia microgrids have difficulties in voltage and frequency control. That affected saving its stability and preventing a blackout. To improve low inertia islanded microgrids' dynamic response and save their stability, this paper presented relative rate observer self-tuning fuzzy PID (RROSTF-PID) based on virtual inertia control (VIC) for an islanded microgrid with a high renewable energy sources (RESs) contribution. RROSTF-PID based on VIC's success in showing remarkable improvement in the microgrid's dynamic response and enhancement of its stability. Moreover, it handles different contingency …

Characterization Of Materials Properties In Additively Manufactured Aisi-420 Martensitic Steel Deposited By Laser Engineered Net Shaping, Md Mehadi Hassan

Nanoscience and Microsystems ETDs

Metal additive manufacturing (AM) is a disruptive technology enabling the fabrication of complex and near-net-shaped parts by adding material layer-wise. It offers reduced lead production time. AM processes are finding applications in many industrial sectors such as aerospace, automotive, biomedical, and mold tooling. Despite the tremendous advantages of AM, some challenges still prevent this technology's adoption in high-standard applications. Anisotropy and inhomogeneity in the mechanical properties of the as-built parts and the existence of pores and lack-of-fusion defects are considered the main issues in directed energy deposition (L-DED) parts. Laser-engineered net shaping LENS® offers excellent possibilities to fabricate metal tools …

Backpack Effects On Two-Dimensional Gait Spatiotemporal And Kinematic Parameters, Nardo Rizaldy, Alvin Alvin, Wirawan Lingga, Ethan B.W. Goeij, F. Ferryanto

Journal of Mechanical Engineering Science and Technology (JMEST)

Loads could affect the body gait in various ways. Backpacks, sling bags, suitcases, and even trolleys could hugely affect human gait without us realizing it. The effects of these loads have been scientifically researched in biomechanics and sports science for the past few years. For instance, the comparison of walking with and without a backpack could easily reveal significant differences in body segments, which could be utilized for therapy and medicine development. The aim of this research is to determine the differences of the spatiotemporal kinematic parameters between a conventional human gait and a backpackloaded gait. Some parameters to be …