Mechanical Engineering Commons^™

Wrinkling Of Membrane And Thin Film Under Torsion, Tingting Chen

Dissertations and Theses

Membranes and thin film structures are widely used in modern technologies. Applications include solar sails and sunshields in space missions, biological membranes and flexible circuit boards. Wrinkling of membrane or a stiff film on a soft substrate may occur in either desired or unwanted patterns. This work tries to obtain some understanding on the wrinkling phenomenon and provide guidance in avoiding wrinkling or effectively controlling the wrinkle patterns.

Many works have been published about wrinkling in the thin sheets since the 20^th century. However, there is no simple analytical way to systematically characterize the wrinkling in these studies. In …

Dynamics Of A Threshold Shock Sensor: Combining Bi-Stability And Triboelectricity, Daniel S. Nelson, Alwathiqbellah Ibrahim, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

A proof of concept of a triboelectric threshold shock sensor and its characterization are presented. Shock sensors are used in many applications in the automotive, shipping and other industries, mainly to determine if acceleration thresholds are met. Many shock sensors are only mechanical, so the only way to know if the threshold has been reached is to physically check the device. There are noticeable advantages of using triboelectric transduction and bi-stability to create a shock sensor. By combining a buckled-beam structure and a triboelectric generator, we created a proof of concept of a tunable threshold shock sensor. The sensor generates …

Bayesian Model Averaging Based Storage Lifetime Assessment Method For Rubber Sealing Rings, Di Liu, Shaoping Wang, Chao Zhang, Mileta M. Tomovic

Engineering Technology Faculty Publications

Rubber sealing ring is one of the most widely used seals. It is always stored for a period of time before put into use, especially in aeronautic and aerospace applications. It is necessary to evaluate the storage lifetime of rubber sealing rings. However, due to the long storage lifetime of rubber sealing rings, two issues need to be handled, including model uncertainty and lack of storage lifetime data. A Bayesian model averaging based storage lifetime assessment method for rubber sealing rings is proposed in this article. The Gamma distribution model and Weibull distribution model are selected as the candidate models …

Void Fraction Measurements In Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensor And Pressure Transducers- Effect Of Sparger, Afolabi Gabriel Ojo

Dissertations and Theses

The importance of the accurate temporal and spatial measurements of the two-phase flow parameters in bubble columns is very well known. The aim of this research work is to report the spatial measurements of the void fraction distribution in a 30 cm diameter cylindrical bubble column using Wire Mesh Sensor (WMS) tomography and Pressure Transducers. Pair of WMS sensors, with a 64×64 wire configuration of each sensor, were installed which are separated by a distance along the axis of the bubble column. Wire Mesh Sensors and PTs Data were collected for time-averaged and transient with a sampling frequency of 1000 …

The Influence Of Size And Progression Of Intra-Cerebral Hematoma On The Lateral Ventricles, Muhammad J. Ashraf

Dissertations and Theses

Cerebrovascular diseases like intra cerebral hemorrhage are quite deadly and may disturb functioning of the brain, expanding and resulting in formation of an intra cerebral hematoma(ICH). It is imperative to comprehend how hematoma and its expansion inside the brain endangers human life. One of the influences of an ICH inside brain tissue is on the Lateral Ventricles(LV). When the hemorrhage occurs close enough to the lateral ventricles, filled with cerebrospinal fluid(CSF), it disrupts the balance of fluid in LV. A minor pressure change in LV can negatively influence the production of CSF as well as an increase in intracranial pressure. …

Literature Survey Of Wet-Waste And Hydrothermal Carbonization System: A Comparative Evaluation, Ramat Olaide Yusuf

Dissertations and Theses

This thesis describes the process of Hydrothermal carbonization and a comparative assessment on recent work done on the process using different feedstocks such as Raw Apple (RA), Apple chip pomace (ACP), apple juice pomace (AJP), grape pomace (GP), macadamia nut-shell (MNS), Sewage Sludge (SS), Poultry Litter (PL) and Grape Marc (GM). The data obtained from the literature survey was compared with the data obtained by the CCL team on the SWPS gasifier (HTC of poultry litter) to obtain how carbon conversion efficiency, syngas composition, thermal efficiency, char production rate, gas production rate and energy utilization vary with carbonization process conditions, …

Void Fraction Measurements In A Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensors And Pressure Transducers: Effect Of Spargers, Afolabi G. Ojo

Dissertations and Theses

The importance of the accurate temporal and spatial measurements of the two-phase flow parameters in bubble columns is very well known. The aim of this research work is to report the spatial measurements of the void fraction distribution in a 30 cm diameter cylindrical bubble column using Wire Mesh Sensor (WMS) tomography and Pressure Transducers. Pair of WMS sensors, with a 64×64 wire configuration of each sensor, were installed which are separated by a distance along the axis of the bubble column. Wire Mesh Sensors and PTs Data were collected for time-averaged and transient with a sampling frequency of 1000 …

Development Of Electromagnetic Friction Dampers For Improving Seismic Performance Of Civil Structures, Mohsen Amjadian

Dissertations and Theses

Energy dissipation is critical to limiting damage to civil structures subjected to extreme natural events such as earthquakes. Friction is one of the most reliable mechanisms of energy dissipation that has been utilized extensively in friction dampers to improve seismic performance of civil structures. Friction dampers are well-known for having a highly nonlinear hysteretic behavior caused by stick-slip motion at low velocities, a phenomenon that is inherent in friction and increases the acceleration response of the structure under control unfavorably, in spite of the fact that the displacement is generally reduced because of the energy dissipation. This increase in acceleration …

Experimental Analysis Of Protective Headgear Used In Defensive Softball Play, John Scott Strickland

UNF Graduate Theses and Dissertations

Every year in the United States, an estimated 1.6 to 3.8 million people sustain sports-related traumatic brain injuries (TBIs), with an appreciable number of these injuries coming from the sport of softball. Several studies have analyzed the impact performance of catcher’s masks within the context of baseball; however, virtually no studies have been performed on fielder’s masks within the context of softball. Thus, the main objective of the present work was to evaluate the protective capabilities of softball fielder’s masks. To better understand the injury mechanisms and frequency associated with softball head/facial injuries, epidemiological data from a national database was …

Landing-Gear Impact Response: A Non-Linear Finite Element Approach, Tuan H. Tran

UNF Graduate Theses and Dissertations

The primary objective of this research is to formulate a methodology of assessing the maximum impact loading condition that will incur onto an aircraft’s landing gear system via Finite Element Analysis (FEA) and appropriately determining its corresponding structural and impact responses to minimize potential design failures during hard landing (abnormal impact) and shock absorption testing. Both static and dynamic loading condition were closely analyzed, compared, and derived through the Federal Aviation Administration’s (FAA) airworthiness regulations and empirical testing data.

In this research, a nonlinear transient dynamic analysis is developed and established via NASTRAN advanced nonlinear finite element model (FEM) to …

Numerical And Experimental Validation For The Optimization Of Directed Energy Deposition Processing Parameters, Luis Nunez

Graduate Research Theses & Dissertations

In order to capitalize on the cost effectiveness of Metal Additive Manufacturing (MAM) it is critical to understand how to build components with consistency and high quality. Directed Energy Deposition (DED) is a MAM method for creating parts layer by layer through the use of a moving heat source and powder material inserted into the melt pool generated on the substrate. DED like most MAM processes are highly complex due to the rapid thermal gradients experienced during processing. These thermal gradients are determined by a variety of processing parameters which include laser power, powder feed rate, travel speed, layer height …

Static Load Bolted Joint Elastic Resilience Testing Methodology, Paul Melino

Electronic Theses and Dissertations

Elastic resilience is the ratio of deformation over force an object experiences when under stress. Knowing the how much the bolt and clamped part deform under load is critical when determining fasteners for a bolted joint. VDI 2230 is the internationally recognized bolt sizing standard and contains the equations used to determine each of the bolted joint component’s resilience as well as values for embedment estimates based on component surface roughness. Embedment is the local plastic deformation due to uneven contact over the contact planes of a bolt-clamped interface (Bolt head to plate, plate to plate, plate to nut, and …

Introduction For The Special Issue On Beyond The Hypes Of Geospatial Big Data: Theories, Methods, Analytics, And Applications, Qianxing Wang, Allison Kealy, Shengjie Zhai

Mechanical Engineering Faculty Research

We live in the era of ‘Big Data’. In particular, Geospatial data, whether captured through remote sensors (e.g., satellite imagery) or generated from large-scale simulations (e.g., climate change models) have always been significantly large in size. Over the last decade however, advances in instrumentation and computation has seen the volume, variety, velocity, and veracity of this data increase exponentially. Of the 2.5 quintillion (1018) bytes of data that are generated on a daily basis across the globe, a large portion (arguably as much as 80%) is found to be geo-referenced. Therefore, this special issue is dedicated to the innovative theories, …

Analysis Of Radiation Damage In Electronics Of Unmanned Aerial And Ground Robotic Platforms, Monia Kazemeini, Alex Barzilov, Woosoon Yim, Jean Chagas Vaz

Graduate & Professional Student Association Research Forum

• Radiation measurements are necessary for a routine monitoring of nuclear facilities and during emergencies, such as the Fukushima Daiichi nuclear power plant accident

• Robotic platforms are utilized to carry radiation sensors to allow for remote sensing and sampling operations

• Unmanned Aerial Systems (UAS) and Unmanned Ground Vehicle (UGV)

• Robots might be exposed to the ionizing radiation (high dose levels are possible)

• Irradiation causes defects in devices and components leading to malfunctions and limiting the robot capabilities, decreasing its operational time

• The goal is to complete scheduled tasks while the robot is being irradiated

• …

Infection Control In Total Knee Replacement Prosthesis Using Nitric Oxide Releasing Biomaterials, Ashley Widing

Master's Theses

Replacing a weight-bearing joint is accompanied by long procedures, even longer recovery times, and intensive monitoring. This burden increases after infection; a complication requiring revision surgeries and therefore extensive additional recovery time. Infection can present itself at any time during the process, making it hard to predict. Currently, a two-part revision surgery is completed by removing all infected tissue and implanting an antibiotic spacer. The spacer fills the joint gap and is removed prior to the revision total knee replacement. A revision total knee replacement follows the same procedure as the initial surgery. Not only is this detrimental to patient …

Effect Of Perturbations On The Dominant Flow Structures In A Rectangular Lid-Driven Cavity With Particle Suspensions, Siva Bolisetty

Graduate Research Theses & Dissertations

The lid-driven cavity is a canonical problem in the field of analytical and computational fluid dynamics. This work is focused on a 2-D rectangular cavity with a length twice the size of its width and consists of an incompressible fluid with a moving upper wall/lid while the rest of the wall boundaries are subjected to fixed, no-slip, zero-velocity boundary conditions. The objective is to investigate the effect of perturbations resulting from particle drag and particle collisions on dominant flow structures of the fluid within this cavity. The dominant flow structures in a rectangular lid-driven cavity constitute a primary vortex, a …

The Characterization And Fatigue Life Impact From Surface Roughness On Structurally Relevant Features Produced Using Additive Manufacturing, Eric-Paul Daniel Tatman

Browse all Theses and Dissertations

Additive manufacturing (AM) produces rough surfaces that are detrimental to the mechanical performance of the part. In this work, downward-facing surfaces were fabricated in alloy 718 using laser powder bed fusion and investigated with surface characterization and axial fatigue testing. Coupons with downward-facing surfaces at 45°, 60°, and 75° and flat axial fatigue bars with as-built and machined holes were built. Both specimens were fabricated with three levels of downskin laser power and the coupons with three levels of downskin laser speed. Surface characterization showed roughness increased as the downward-facing angle decreased. Fatigue testing with digital image correlation showed localized …

A Tunable Electrostatic Mems Pressure Switch, Mark Pallay, Ronald N. Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

We demonstrate a tunable air pressure switch. The switch detects when the ambient pressure drops below a threshold value and automatically triggers without the need for any computational overhead to read the pressure or trigger the switch. The switch exploits the significant fluid interaction of a MEMS beam undergoing a large oscillation from electrostatic levitation to detect changes in ambient pressure. If the oscillation amplitude near the resonant frequency is above a threshold level, dynamic pullin is triggered and the switch is closed. The pressure at which the switch closes can be tuned by adjusting the voltage applied to the …

State Estimation For An Agonistic‐Antagonistic Muscle System, Thang Tien Nguyen, Holly Warner, Hung La, Hanieh Mohammadi, Daniel J. Simon, Hanz Richter

Electrical and Computer Engineering Faculty Publications

Research on assistive technology, rehabilitation, and prosthetics requires the understanding of human machine interaction, in which human muscular properties play a pivotal role. This paper studies a nonlinear agonistic‐antagonistic muscle system based on the Hill muscle model. To investigate the characteristics of the muscle model, the problem of estimating the state variables and activation signals of the dual muscle system is considered. In this work, parameter uncertainty and unknown inputs are taken into account for the estimation problem. Three observers are presented: a high gain observer, a sliding mode observer, and an adaptive sliding mode observer. Theoretical analysis shows the …

Paddle Mixer-Extrusion Reactor For Torrefaction And Pyrolysis, Stas Zinchik

Dissertations, Master's Theses and Master's Reports

This work is focused on the fundamental understanding and the development of paddle mixer reactors (or modified screw augers). This work will contribute to the effort of the thermal conversion of biomass and wastes. We developed and studied two paddle systems (i) 25-mm lab-scale (up to 1 kg/hr) and (ii) 101-mm pilot-scale (up to 100 kg/hr). Thermal behavior of the two systems was studied and it was estimated that the lab-scale system has a high heating rate of up to 530 °C/s. Residence times were thoroughly measured and were determined as a function of rotation frequency and volume fraction. We …

Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang

Theses and Dissertations--Chemistry

Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with …

Direct Polymer Grafting As A Method Of Maintaining The Mechanical Properties Of Cellulose Nanocrystals In The Presence Of Moisture, Mary Elizabeth Breen-Lyles

Graduate Research Theses & Dissertations

Cellulose nanocrystals (CNCs) are a distinctive nanomaterial derived from cellulose, the most abundant natural polymer on Earth, and the primary reinforcing structural component of cellulose fibrils found within the plant cell wall. These nanocrystals exhibit mechanical properties comparable to synthetic aramid fibers but are advantageous as they are biodegradable, renewable, and can be produced sustainably as they are predominantly extracted from naturally occurring cellulosic materials. These qualities make it a sustainable, highly renewable and environmentally friendly material to be used in place of synthetic materials in a variety of applications. With their high surface area to volume ratio, low level …

Studying The Effect Of Vacancies On The Thermal Conductivity Of Metal-Coated Carbon Nanotubes Using Molecular Dynamics Atomistic Simulations, Ravindra Sunil Dhumal

Graduate Research Theses & Dissertations

Breakthroughs in nanotechnology have made it possible for the size of electronic gadgets to be scaled down to micro/nano level. What follows however, is the side effect of high power densities and overheating as the heat dissipation is restricted to very small surface area. Thus, the need of an effective thermal management system is central to these developments. One way to counter this problem is to use Thermal Interface Materials (TIMs) which promote heat transfer between heat source and sink.

Owing to their high thermal conductivity (up to 6000 W/mK), Carbon Nanotubes (CNTs) are thought of as strong candidates for …

Steady Flows In Annular Wedge Lid-Driven Cavities, Anandan Ganapathy

Graduate Research Theses & Dissertations

The lid-driven cavity is a well-known canonical problem in the field of analytical and computational fluid dynamics. It is comprised of a square domain of an incompressible fluid with its upper lid has a specified velocity and the remaining wall boundaries are subjected to fixed, no-slip, zero-velocity constraints. There are numerous examples found in the literature that address the well-known, stable behavior of this system, which includes a primary recirculating vortex, secondary corner vortices, and a velocity profile through the center midpoint y-axis that is shown to be dependent on the Reynolds number. In this investigation, the shape of the …

Proper Orthogonal Decomposition Analysis Of Lid-Driven Cavity Flows Containing Particle Suspensions., Nitin Katiki

Graduate Research Theses & Dissertations

Previous experiments done on the square lid driven cavity have shown that its stability and transitional behavior, and by extension the behavior of more complex flows, can be greatly modified by introducing systematic disturbances called perturbations to its flow field. In this study, a square lid driven cavity is calculated in two-dimensional space and perturbed by means of particles suspended in the flow. The perturbations manifest as subtle changes in the flow field velocity and overall flow structure, these are caused by the particle-fluid drag interaction and the particle-particle collision interaction. To understand the nature of these changes and their …

Temporal Dynamics Of Human Emotional Response To Aversive Stimuli, Joseph Lawence Kempel

Graduate Research Theses & Dissertations

Emotions are an integral part of human expression and are often communicated nonverbally through behavioral actions. With advancements in electroencephalography (EEG) technology it is now possible to measure the dynamics of emotion generation in an individual on the basis of patterns in their brain activity. This thesis aims to model the temporal dynamics of human emotion generation upon exposure to aversive stimuli and measure the effect of external distractions as a viable emotion regulation strategy.

This research builds on previous work in the literature that has shown that the ability of humans to regulate their emotions intrinsically (based on their …

Implementation Of The Shpb System For Material Property Test Under High Strain Rate Deformation, Jiaqi Zhu

Graduate Research Theses & Dissertations

Since Bertram Hopkinson first raised the concept of Hopkinson pressure bar in 1914, many efforts have been taken by engineers and scholars for developing the system to measure the stress pulse propagation in metal bars for studying the properties of different materials under high strain rate deformation. The Northern Illinois University Material’s Lab has also built two generations of the split Hopkinson pressure bar (SHPB) system with the effort of several senior design teams in history.

The aim of this study is to develop the existing SHPB system of NIU to make it function properly. By redesigning the gun barrel, …

A Computational Fluid Dynamics Analysis Of The Aerodynamic Performance Of Wind Turbine, Ashkan Ostovari

Graduate Research Theses & Dissertations

Renewable energy resources are likely to be a future energy solution. Among them, the wind has gained a lot of interest. Despite the theoretical limitation in wind energy harnessing efficiency, it is, still, one of the most promising renewable resources with utilizing turbines to extract this energy. Wind turbines, based on their axis of rotation are categorized into vertical axis wind turbine (VAWT) and horizontal axis wind turbine (HAWT), which HAWT’s have shown relatively higher efficiency than VAWT’s. The aim of this thesis is first to develop a scaled-down model of a wind turbine in Computational Fluid Dynamics (CFD) environment …

Developing A Commercial Product Using A Consumer Grade 3d Printer, Calvin Smith

All Graduate Theses, Dissertations, and Other Capstone Projects

The development of affordable, quality, consumer grade 3D printers has allowed entrepreneurs to develop new products and start small businesses. As the print quality of consumer grade printers has improved entrepreneurs have been able to develop consumer quality products without the traditional expense of mass manufacturing. This change from mass manufacturing to small scale and custom production has allowed for the growth of small businesses. Websites such as www.etsy.com show hundreds of small businesses based on 3D printing, these businesses showcase thousands of products ranging from useful household items to cosplay. This thesis covers the process of a small business …

Developing A Testing Instrument To Evaluate The Performance Of 3d-Printed Body-Powered Prosthetic Hands, Araz Al-Dawoodi

All Graduate Theses, Dissertations, and Other Capstone Projects

A 3D printed prosthetic hand is an open source technology that became a good substitution for many products in the market. For many reasons, Low-cost, easy made / easy build. As an open source product, 3D printed prosthetic designs are available to anyone around the world, a good option for young children because they need to have a new prosthetic more frequent until they reach the adulthood age. Most families cannot pay a thousand dollars technology. From the research, it found that that there are not enough studies cover the open source wrist body-powered prosthetic. Other studies covered products used …