Engineering Commons^™

Tribological Studies Of Thick Polytetrafluoroethylene Coatings Enhanced By Polydopamine And Nanoparticles, Sujan Kumar Ghosh

Graduate Theses and Dissertations

Polytetrafluoroethylene (PTFE) is a popular low friction solid lubricant with high chemical and thermal stability. Thick PTFE coatings have the potential for many tribological applications, such as replacing Tin-based Babbitt materials in journal bearings. However, the weak bonding strength to the substrate and the high wear rate of PTFE coatings are current limiting factors. The lack of understanding of their tribological properties and wear mechanisms in oil-lubricated conditions and how coating thickness affects the tribological performance further hindered the use of PTFE coatings. In this dissertation, polydopamine (PDA), a bio-inspired adhesive, is used as an underlayer for or as a …

Development Of Novel Battery Materials For Lithium-Ion Batteries And Beyond, Jiyu Cai

Graduate Theses and Dissertations

As fossil fuels are depleting and causing environmental issues, it becomes imperative to widely implement renewable energies (e.g., solar and wind power). In this context, electrical energy storage (EES) systems are essential to accommodate the intermittent supply and uneven distribution of renewable energies. To this end, high-energy-density EES devices are highly demanded, such as rechargeable batteries. This dissertation presents my efforts in developing novel battery materials for lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and solidstate lithium batteries (SSLBs). These efforts include electrochemical evaluations of battery materials, surface modifications of electrodes via atomic layer deposition (ALD), and advanced characterizations of batteries …

Phase-Field Modeling Of The Polymer Membrane Formation Process For Micro- And Ultra-Filtration, Michael Rosario Cervellere

Graduate Theses and Dissertations

Porous polymer membrane filters are widely used in separation and filtration process. Micro- and ultra-filtration membranes are commonly used in biopharmaceutical applications such as filtering viruses and separating proteins from a carrier solution. The formation of these membrane filters via phase inversion is a complex and interconnected process where varying casting conditions can have a wide variety of effects on the final membrane morphol- ogy. Tailoring membrane filters for specific performance characteristics is a tedious and time consuming process. The time and length scales of membrane formation make it extremely difficult to experimentally observe membrane formation. Modeling the membrane formation …

Influence Of Extracellular Matrix Stiffness And Topography On Neuronal Cell Behavior And Neurite Outgrowth, Mohan Yasodharababu

Graduate Theses and Dissertations

The focus of regeneration therapy for traumatic brain injuries and Alzheimer's disease is on the promotion and growth of neuronal cells. In vitro research attempts to improve this by modifying the stiffness and topography of the extracellular matrix (ECM). However, the limitations of in vitro experiments make it difficult to control the individual factors influencing neuronal cell growth. A computational model can be used to decouple individual factors and study them individually to gain a better understanding of the mechanics between the neuronal cell and ECM, which will aid in the design of in vitro experimental studies.

This study develops …

The Influence Of Participation In A Multi-Disciplinary Collaborative Service Learning Project On The Effectiveness Of Team Members In A 100-Level Mechanical Engineering Class, Stacie I. Ringleb, Pilar Pazos, Julia Noginova, Francisco Cima, Orlando Ayala, Krishnanand Kaipa, Jennifer Kidd, Kristie Gutierrez

Mechanical & Aerospace Engineering Faculty Publications

Engineers need to develop professional skills, including the ability to work successfully in teams and to communicate within and outside of their discipline, in addition to required technical skills. A collaborative multi-disciplinary service learning project referred to as Ed+gineering was implemented in a 100-level mechanical engineering course. In this collaboration, mechanical engineering students, primarily in the second semester of their freshman year or first semester of their second year, worked over the course of a semester with education students taking a foundations course to develop and deliver engineering lessons to fourth or fifth graders. Students in comparison engineering classes worked …

Review: Factors Affecting Composite Laminates Against Lightning Strikes, Aaryan Manoj Nair

Publications and Research

Lightning strike protection (LSP) have recently been a newly developing field particularly with the emergence of graphene thin film integration into carbon fiber composite structures. This technology has a widespread application in airplanes, wind turbines, and other instruments which are susceptible to frequent lightning strikes. Electrical discharge of the instrument in a safe manner is vital for the safety of the passengers (in the case of flights) as well as the integrity of the aircraft structures because of their specific mechanical and structural properties, which are essential for their functioning. The purpose of the study is to fabricate graphene thin …

Anisotropic Plasticity Modeling Of Thin Sheets And Its Application To Micro Channel Forming Of Steel Foils, Jie Sheng

Mechanical Engineering Research Theses and Dissertations

Thin sheet metals and ultrathin metal foils produced by industrial rolling processes are textured polycrystalline materials and their mechanical behaviors may depend strongly on the orientation of applied loading. Consideration of such plastic anisotropy in advanced modeling of these materials is of the paramount importance in designing optimal manufacturing processes for automotive and other applications using finite element methods. This research addresses several critical issues in anisotropic plasticity modeling and its applications in analyzing micro channel forming of ultrathin stainless-steel foils. An experimental study has first been carried out on the accuracy and sensitivity of measuring the plastic strain ratios …

Handwriting Correction System Using Wearable Sleeve With Optimal Tactor Configuration, Dhanya Nair, Grant Stankaitis, Sean Duback, Robert Geoffrion, Justin B. Jackson

Engineering Faculty Articles and Research

Handwriting remains an elusive skill with practice worksheets being the common method of learning. Since these worksheets provide only visual feedback and no quantitative feedback, it can often be a challenge to improve. For children with learning disabilities, learning handwriting skills is one of the most difficult tasks. We propose a handwriting training system that uses off-the-shelf webcam, a pen tracking software and a haptic sleeve which provides active feedback to the user based on their deviation from the original pattern. The sleeve has 4 individual motors that vibrate at different intensities based on the direction (right, left, up or …

Scalability Of The Size Of Patterns Drawn Using Tactile Hand Guidance, Dhanya Nair

Engineering Faculty Articles and Research

Haptic feedback for handwriting training has been extensively studied, but with primary focus on kinematic feedback. We provide vibrotactile feedback through a wrist worn sleeve to guide the user to recreate unknown patterns and study the impact of vibrational duration (1, 2, 3 seconds) on pattern scaling. User traces a line at 90° angles, while attempting to maintain a constant speed, in the direction of the motor activated till a different motor activation is perceived. Shape and size are two features of good letter formation. Study performed on three subjects showed the ability to utilize four vibrotactile motors to guide …

High Temperature Degradation In Gan-Based Hall Effect Sensors, Alexis Anne Krone

Graduate Theses and Dissertations

This research focuses on understanding the effects of accelerated aging through temperature and environment on novel gallium nitride-based Hall effect magnetic field sensors and determining device reliability under electric vehicle operating conditions. The device reliability was modeled using accelerated aging for the temperatures of 200 °C, 350 °C, 450 °C, and 600 °C under various time steps unique to each temperature and either air, which is identical to operating circumstances, or argon, which would model the hermetic packaging environment. Using a high temperature furnace and oven, devices underwent high temperature storage tests at a chosen temperature and time step. Afterwards, …

Interrelation Of Thermal Stimulation With Haptic Perception, Emotion, And Memory, Mehdi Hojatmadani

USF Tampa Graduate Theses and Dissertations

Haptics is an interdisciplinary field of science that deals with how humans perceive and respond to different sensory cues perceived through touch. Thermal haptics as a branch deals with how humans perceive the temperature sensation and respond to that. The process in which thermal perception occurs is well known to researchers. What seems missing in the literature is how temperature interacts or sometimes intervenes in other physiological and psychological aspects of our lives. In this research, a series of studies are presented where the main focus was how temperature and brain interact with each other to impede or enhance our …

Event-Triggered Control Architectures For Scheduling Information Exchange In Uncertain And Multiagent Systems, Stefan Ristevski

USF Tampa Graduate Theses and Dissertations

Despite the numerous advantages that networked controlled systems provide, potential network overload in these systems can severely degrade their performance and even cause catastrophic failures. To this end, the work presented in this dissertation provides a neat solution on reducing network utilization in uncertain networked controlled systems using an adaptive event-triggered control approach predicated on a novel dynamical threshold and information exchange methodology while guaranteeing closed-loop system stability.

In particular, consider a system consisting of an operator (e.g, a ground station) and an uncertain controlled dynamical system (e.g., a vehicle equipped with feedback control algorithm), where the aim of the …

Optimization Of 3d Printed Mold Performance For Injection Molding Via Hollow Infill Patterns, Alan Fong

University Honors Theses

The applicability of hollow infill patterns has been explored for its applications in making 3D printed polymer-based injection molds in the additive manufacturing industry. Hollow infill patterns offer a significant reduction in material costs as well as the opportunity for reducing the cooling times via pumping a coolant fluid through the hollow cavity in a similar fashion to traditional conformal cooling channels. A 3D Jacks Support Hollow mold model was determined to be the best performing design. FEA analysis was conducted to determine the maximum reduction in internal volume (percentage of material saved) that could be achieved without exceeding the …

Bioinspired Fabrication Of Reconfigurable Elastomeric Cementitious Structures Using Self-Healing Mechanical Adhesives Interfaces, Vanessa Restrepo, Ramses V. Martinez

Purdue University Libraries Open Access Publishing Fund

Modern construction technologies are in high demand of new highly customizable and easy-to-assemble structural materials with enhanced mechanical performance and the capability to self-repair autonomously. This article describes the simple and cost-effective manufacturing of Self-Healing Elastomeric/Cementitious/Mechanical Adhesive Structures (SECMAS). SECMAS are comprised of cementitious bricks joined by mechanical adhesive interfaces and organized in nacre-inspired, brick-and-mortar structures. This scalable staggered design provides SECMAS with the capability to concentrate the formation and propagation of cracks along the mechanical adhesive interfaces, which efficiently distribute loading forces and accommodate deformation. The periodic distribution of elastomeric reinforcing layers inside the SECMAS facilitates its elastic self-recovery …

Jme 4110: Vibratory Parts Feeder, Adin Stambolic, Patrick Edward Vastola, Noah Herrin

Washington University / UMSL Mechanical Engineering Design Project JME 4110

Design an inexpensive, modular and tunable vibratory feeder to move different size particles from one place to another. The feeder can change according to the shape and size of the particles while in use.

Jme 4110: Extended Hole Punch, Lucas Mennemeier, Jason Zobrist

Washington University / UMSL Mechanical Engineering Design Project JME 4110

DESIGN AND DEVELOP A WORKING PROTOTYPE OF A SINGLE-HAND, SINGLE-HOLE PUNCH WITH AN EXTENDED THROAT THAT WILL BE ABLE TO REACH FURTHER INTO A SHEET OF PAPER THAN A STANDARD SINGLE-HOLE PUNCH. THIS CAN BE A PUNCH ATTACHMENT OR A STAND-ALONE DEVICE. EITHER DESIGN CHOSEN WILL ALSO BE ABLE TO BE CONVERTED INTO AN EMBOSSING TOOL FOR EMBOSSING SEALS INTO DOCUMENTS

Jme 4110: Mass Production Of Multi-Sphere Approximated Parts, Christopher Hartley, Chad Gorski, Matthew Brady

Washington University / UMSL Mechanical Engineering Design Project JME 4110

For this project, the team needs to design a mass production manufacturing process. The product of the process will be parts that represent, as closely as possible, approximations of parts developed using Discrete Element Modelling (DEM) software. Since the software uses spheres to efficiently model complex parts, the manufacturing process must also utilize spheres as the building blocks for the approximated parts. As a proof of concept, this project uses river pebbles as the parts being approximated by the software and modeled by the multi-sphere production process.

Jme 4110: Water Reservoir Energy Storage, Kristen Grace, Supapan Thammanok, Leticia Zoratto Lunge

Washington University / UMSL Mechanical Engineering Design Project JME 4110

The goal of this project was to create a demonstrative model of a Pumped Hydroelectric Storage System (PHS). A PHS stores energy by draining water from an upper reservoir through a turbine to generate electricity. This water is then pumped from a lower reservoir to the original upper reservoir to restart the system cycle. Using existing PHS applications, a small-scale prototype was built using an aquarium pump and mini turbine, along with PVC and plastic containers. When water is run through the system, a multimeter can be used to show the power output of the system. In addition to functionality, …

Jme 4110: Drag Line Wind Energy Generator, David Gengenbacher, Mouhamadou Bamba Kane, Brian Bakula

Washington University / UMSL Mechanical Engineering Design Project JME 4110

The goal of this project was to develop a prototype capable of power a 10 watt light bulb using only the energy from wind.

Jme 4110: Lego-Lock Block, Diana Engelhardt, Dmitriy Kornyukhov, Chelsea Borders

Washington University / UMSL Mechanical Engineering Design Project JME 4110

Design a building block device that assembles similarly to a LEGO brick, but also has the capability to lock an assembly state between two bricks. Scale (size) not critical for this proof of concept (standard LEGO blocks may be too small for this first attempt).

Jme 4110: Portable Car Wash, Coleman Kaufman, Sara Wilson

Washington University / UMSL Mechanical Engineering Design Project JME 4110

We met with our target customer to understand their needs for the ideal portable car wash. Their key needs included use by any sized passenger vehicle, washing the car as good as a community car wash, and must be portable. We started by researching current products that could match these needs, and then we sketched four of our own designs to match our customer’s needs. With these design sketches we used a metrics tool to determine which design was the best. From there we did engineering calculations to analyze the trouble spots in our design, such as the water pressure …

Jme 4110: Data Cooling Center, Christopher Schmidt, Brennan Fogarty, Suruchi Aryal

Washington University / UMSL Mechanical Engineering Design Project JME 4110

The group will design a way to efficiently move heat within a framework of using dielectric fluid as a heat transfer medium. The heat will be removed from a data center or a simulated data center. The group will evaluate the best possible design with the understanding that cooling data centers generate a large amount of heat. The design will also be constructed in such a manner that it can be scaled up to a larger size. Dielectric fluid will be used due to its efficiency compared to that of an air cooled system or a compressed refrigerant system. Account …

The Effects Of Noise On Parametrically Excited Systems With Nonlinear Damping, Donghao Li

Theses and Dissertations

Parametric oscillators are a class of resonating systems in which a parameter, such as stiffness in a mechanical system or capacitance in an electrical system, is periodically modulated in order to alter the system response in a desired manner. A resonance effect occurs when the pump frequency is near twice of resonant frequency. Such systems are said to be “parametrically pumped,” and this pump can, above a certain amplitude threshold, destabilize the system in the absence of nonlinearities. Parametric resonance is widely observed in nature and has been employed in a large variety of engineered systems, most notably in micro-electro-mechanical …

Analysis Of A Non-Equilibrium Vortex Pair As Aircraft Trailing Vortices, Manuel Ayala

Mechanical & Aerospace Engineering Theses & Dissertations

Shortly after the roll-up evolution of the vortex sheet behind the wings of an aircraft, a coherent counter-rotating vortex pair emerges. Presence of this vortex pair in the downstream of an aircraft, creates unsafe conditions for other aircraft, especially near airport runways. Fundamental knowledge of the physics that govern the formation, duration and dissipation of aircraft wake vortices is desirable in order to improve aircraft operational safety. This study uses non-equilibrium pressure theory to develop an accurate model describing the physical behavior of the vortex pair created by an aircraft in the early to mid-field vortex regime. An isolated aircraft …

The Effect Of Through Thickness Reinforcement On Debonding Behavior Of Skin/Stringer Configuration, Yogaraja Sridhar

Mechanical & Aerospace Engineering Theses & Dissertations

Investigation of this study is to the determine the crack propagation and disbonding in the bonded region of the skin and stringer specimen. An adhesive layer has been used to bond the skin and stringer by using a heat press operation. After the bonding, a drilling method has been adopted to install the through thickness reinforcement in the specimen. The key role of the through thickness reinforcement is to increase the stiffness and strength of the panels and to prevent the crack propagation or disbonding of the panels. The reinforcement was installed in pure (Pristine) samples and in defect samples …

Modeling Interactions In Concentrated Ceramic Suspensions Under Ac Electric Field, Naga Bharath Gundrati

Mechanical & Aerospace Engineering Theses & Dissertations

Colloidal processing of ceramics manipulates the interaction forces using additives or external energy field between the suspending particles to fabricate complex structures. Under AC electric field, mutual dielectrophoretic (DEP) forces between particles create particle chaining. Dielectrophoresis (DEP) is adopted to control ceramic particles in the colloidal suspension, which can benefit from employing DEP forces to externally control the fabrication of ceramic materials with desired porosity and hierarchical structure. To this end, it is crucial to understand the interactions between ceramic particles in aqueous media and AC electric field. The dynamic interactions of ceramic particles under AC electric field are modelled …

Development And Applications Of Adjoint-Based Aerodynamic And Aeroacoustic Multidisciplinary Optimization For Rotorcraft, Ramiz Omur Icke

Mechanical & Aerospace Engineering Theses & Dissertations

Urban Air Mobility (UAM) is one of the most popular proposed solutions for alleviating traffic problems in populated areas. In this context, the proposed types of vehicles mainly consist of rotors and propellers powered by electric motors. However, those rotary-wing components can contribute excessively to noise generation. Therefore, a significant noise concern emerges due to urban air vehicles in or around residential areas. Reducing noise emitted by air vehicles is critically important to improve public acceptance of such vehicles for operations in densely populated areas.

Two main objectives of the present dissertation are: (1) to expand the multidisciplinary optimization to …

Pore-Resolving Simulations To Study The Impacts Of Char Morphology On Zone Ii Combustion And Effectiveness Factor Models, Dongyu Liang, Simcha L. Singer

Mechanical Engineering Faculty Research and Publications

Combustion and gasification of pulverized char often occur under zone II conditions, in which the rate of conversion depends on both heterogeneous reaction and gas transport within the particle's porous structure. The morphology of porous char has a strong influence on intra-particle diffusion, and thus, on the overall conversion rate. Because pulverized coal and biomass char particles are often irregularly shaped and contain pores and voids which can approach the size of the particles themselves, conventional models based on spherical symmetry and coarse-grained, upscaled, effective continuum conservation equations are not applicable or appropriate. A recent 3-D, pore-resolving CFD simulation approach …

Near-Shore Sediment Transport Under Cnoidal Waves Using Particle Image Velocimetry, Jenna Rose Katrina

Theses and Dissertations

With future trends showing a higher percentage of the human population living along the coast, coastal resilience is a significant topic of concern for many researchers. The purpose of this research was to analyze near-shore sediment transport under different wave parameters using the technique of Particle Image Velocimetry (PIV) and laboratory studies for linear and nonlinear cnoidal waves. At the deeper extent of the nearshore profile, waves will tend to be linear, having an Ursell number less than 40, with little or no net sediment transport due to orbital velocities. The velocities are the same under the crest and trough …

Design And Analysis Of A Pipe And Pump System Constructed To Connect Port Canaveral To The Banana River, Nicole Ann Mcclain

Theses and Dissertations

The Indian River Lagoon (IRL) has hosted an extensive array of plants and animals throughout its lifetime, having one of the greatest species’ diversity of all North American estuaries. In addition to the variety of marine wildlife that is supported by the IRL, the system is also a recreational and economic resource for the counties bordering it. The biological integrity of the IRL, however, has shown evidence of decline in the last few decades, due to impaired water quality caused by pollution and disruptions to natural circulation patterns. If far-reaching changes are made to repair the water quality of the …