Mechanical Engineering Commons^™

Mechanistic Undrestanding Of Amorphization In Iron-Based Soft Magnetic Materials, Taban Larimian

ETD Archive

Iron-based magnetic alloys possess very good magnetic and mechanical properties. Among these alloys Fe-Si-B-based alloys show outstanding saturation magnetization and coercivity which makes them great candidates for many industrial applications. Addition of certain elements to the Fe-Si-B base is proven to improve the homogeneity and fineness of microstructure as well as enhance the magnetic behavior of these alloys. In this research work, we have studied the effect of adding copper and niobium to the Fe-Si-B base alloy. Previous studies have shown that magnetic alloys show better magnetic properties when their microstructure consists of nanocrystals embedded in an amorphous matrix. In …

Understanding Thermal Comfort Impact And Air Movement Around Open Stairs Through The Use Of Cfd Modeling, Ethan Davidson

Graduate Theses and Dissertations

The air exchange between two floors of a building has an impact on thermal comfort. The present research attempts to quantify this impact and identify the contributing factors disrupting the thermal comfort on and around stairs. Various heating and cooling scenarios were analyzed, using CFD modeling, in a simple two-story building separated by a single staircase. The research examines a single building layout with a fixed inlet and outlet configuration. In addition, the study investigated the short-term impact on thermal comfort. As a result, the duration of the simulations varies from two and half minutes to ten minutes, consistent with …

Development Of An Accelerated Life Testing Method For Reliability Assessment Of Wire Bonded Interconnects Subjected To Mechanical And Electromigratory Stresses, Whit Vinson

Graduate Theses and Dissertations

Power electronic advancement trends indicate that device power density will continue to increase as a result of increased power requirements and desired device form factor reduction in order to reduce weight and material costs and increase ease of integration into next-generation power systems. With these advancements come concerns regarding device reliability. The compounded effects of increased power density and form factor reduction in electrical conductors will yield amplified joule heating effects in addition to the already increasing device temperature profiles resulting from the incorporation of wide bandgap technology into power systems. Joule heating effects can lead to a variety of …

The Development And Characterization Of Piezoelectric- Magnetostrictive Smart Self-Sensing Composites, George Relebohile Qhonosheane

Mechanical and Aerospace Engineering Dissertations - Archive

The composites industry is expanding due to the growing global demand for high-performance materials. How do you ensure the production of composites is as smooth and effective as possible while maintaining the high quality of the material? The key issues in composites include crack occurrence, sticking to molds in the production process, and durability differences during their operation. However, monitoring such cases can be challenging. The industry is in need of a smart solution to be able to obtain accurate data from the raw material. This work focuses on the development of smart composite materials. The word composite comes from …

Assessment Of Contaminant Flowpaths In Airside Economization And Analysis Of Thermal Performance At Tank And Server Level For Single-Phase Immersion Cooled Data Centers, Satyam Saini

Mechanical and Aerospace Engineering Dissertations - Archive

The last two decades of 2000 have seen an explosion of utilization and reliance on digital technologies and platforms. During this time, electronic devices have undergone intense miniaturization and a corresponding rise in power densities. In parallel to these developments, data center proliferation has been driven by the increasing utility of revolutionary technologies such as Machine Learning, Artificial Intelligence, e-commerce and, the Internet of Things. Data centers, thus, have become the core of the modern digital age. The primary bottleneck, however, due to extensive device miniaturization and data center proliferation has always been thermal management. Many of the aforementioned technologies …

Development Of An Electro-Pneumatic Servo Clutch And Industry-Level Controller, Timothy Stevens

Mechanical and Aerospace Engineering Theses - Archive

This thesis covers the simulation and development of an electro-pneumatic servo clutch used on an FSAE racecar. This project utilizes a sophisticated simulation and various techniques to increase performance such as utilizing pulse-width and pulse-frequency modulation and the use of a 36V supply with constant current limiting to drive the solenoids. The clutch is actuated using a pneumatic cylinder with the internal pressure modulated using commercially available CNG fuel injectors. This thesis also describes the development of the electronic controller designed using analog circuits, as well as the integration of digital circuits to control operations such as launch control and …

Computational Reliability Analysis Of Blind Micro-Via With 3d And Axisymmetric Multi-Layer Pcb, Jayendra Bazaru

Mechanical and Aerospace Engineering Theses - Archive

Micro-via are components that are used to form connections from one layer to another in most Multilayered Printed Circuit Boards (PCBs). The failure of Micro-via has always been a concern of the electronic industry. The failures are exaggerated during the reflow process due to the high thermal loading. Electronic components have become ubiquitous in our society. It is important to take some measures to reduce (or) eliminate the failures at interconnects in the Printed Circuit Board to obtain highly reliable Input/Output (I/O). This work is based on a hypothetical belief that the possible cause of failure is an insufficient or …

Enhancing Stability Of High-Nickel Cathodes For Lithium-Ion Batteries Through Additive Manufacturing Of Cathode Structure, Matthew Sullivan

Mechanical Engineering Undergraduate Honors Theses

Lithium-ion batteries (LIBs) are currently the best method to store electrical energy for use in portable electronics and electronic vehicles. New cathode materials for LIBs are consistently studied and researched, but few are as promising and attainable as nickel-rich transition metal oxides such as LiNi1-x-yMnxCoyO2 (NMC). NMC materials exist with many different mass ratios, but higher nickel content materials provide higher energy density. With this increase in capacity comes a sacrifice with cyclability, as high-nickel NMC variants are prone to structure collapse, transition metal dissolution, and cracks due to volume change. In this report, mechanical modification of the electrode by …

Atomic Force Microscopy Based Dna Sensing And Manipulation, Matthew Shubert

Mechanical Engineering Undergraduate Honors Theses

Sequencing DNA provides a positive impact for the biomedical community by understanding a wide variety of applications such as human genetics, disease, and pathogens. The reason the Arkansas Micro & Nano Systems lab is involved with research in DNA sequencing is due to the current, leading industry method. Nanopore sequencing was developed by Oxford Nanopore Technology in which its sequencing method separates double stranded DNA to electrically characterize individual nucleotides traveling through a charged nanopore. Unfortunately, nanopore sequencing uses biological materials that require a shelf life and drives high cost. Therefore, the Arkansas Micro & Nano Systems lab has developed …

Durability Of Non-Metallic Materials For Additively Manufactured Heat Spreader Fabrication, Rafael Estrella

Mechanical Engineering Undergraduate Honors Theses

Power electronics are necessary to convert power from DC sources for AC applications. As this technology trends toward smaller packaging for denser power loads, the increased electrical losses result in deleterious excess heat. Thermal management devices are required to prevent the effects of thermal runaway from shortening the longevity of these modules. Nonmetallic jet impingement heat spreaders provide several benefits in terms of weight and performance over conventional cold plates while not accentuating EMI from the switches in the power module; however, the polymer makeup of the materials previously used for fabricating these devices raises durability concerns under the high …

Autonomous Aerial Vehicles Distributed Control And Interactive Games, Yusuf Kartal

Mechanical and Aerospace Engineering Dissertations - Archive

As the number of quadrotors and other Unmanned Aerial Vehicles (UAVs) increases in industrial and urban areas, the development of reliable engineering methods to control their behavior as they interact with each other becomes of central interest in control research. With the increase in demand for UAVs to work together, several real-life challenges need to be addressed that include the implementation, test, and validation of the control algorithms in flight test experiments. On the one hand, the interests of UAVs may be in harmony to perform certain tasks such as transportation, surveillance and reconnaissance. On the other hand, the interests …

Small Spacecraft Thermal Control Louvers, James Anthony Mullen

Undergraduate Honors Capstone Projects

Small satellites missions are becoming increasingly complex and are requiring more power. These demands lead to temperature fluctuations on the satellite due to spacecraft layout, sunlight and shadow in orbit, and high-powered instrumentation. Products which provide necessary thermal stability for components on the satellite are desirable to small satellite manufacturers.

In September of 2015, Dr. Allison Evans of the NASA Goddard Space Flight Center filed a patent for an innovative louver system configured for small satellite applications. The design was sized for satellites with a 1U form factor and utilized bimetallic springs to lift the louver flaps. The design was …

Ng-Torque/Tension Testing Of Bolts With Epoxy Primer, Gabrielle Van Brunt

Undergraduate Honors Capstone Projects

This capstone project is in conjunction with Northrop Grumman (NG). The goal of the project is for NG to apply an epoxy in the future to aerospace structures that they produce. This epoxy is meant to prevent corrosion of threaded joints in the structures. Although NG has the epoxy and has no issues procuring it, NG does not know the properties of the epoxy; it cannot be used until the epoxy’s nut factor is experimentally determined. The epoxy nut factor will be used for design and drawing purposes on various projects. To determine the nut factor, the Aggiepoxy team created …

Calibration Procedure For Dic Strain Measurements During Vibration-Based Fatigue Testing, Benjamin D. Hill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Vibration-based fatigue testing is fast and effective method for determining failure characteristics of a material. Often, a small electrical device called a strain gage is bonded to a rectangular plate specimen to measure the deformation of the plate during a test. However, these strain gages break before the plate does, so an alternative method would improve the results obtained from the test. As an alternative to strain gages, Digital Image Correlation (DIC) is a non-contacting, camera-based technique that measures the deformation of an object by comparing digital images taken before and after the object is deformed. During a vibration-based fatigue …

Thermodynamic Analysis Of A Novel Cycle For Nuclear Smr And Heat Transfer Performance Validation Of The Related Supercritical Working Fluids, Benjamin M. Pepper

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Currently, all operating nuclear power facilities in the U.S. follow the same general design and process: light-water reactors boil water into steam using bundles of nuclear fuel rods as a heat source, pumping that steam through a turbine which powers a generator to produce clean year-round electricity. Water is an effective coolant, but other facilities around the world have demonstrated the ability to use non-water-based coolants in nuclear reactor designs, which consequently have their own trade-offs. Some positive consequences of using different reactor designs include enhanced safety, better economics, and cheaper clean consumer energy. The work described in this paper …

Modeling Energy Efficiency Of Solar Thermal Powered Batch Reverse Osmosis, Lahiri Chitturi

Discovery Undergraduate Interdisciplinary Research Internship

Batch reverse osmosis is the most energy efficient water desalination method and when powered by renewable energy, suggests promise for a cost-effective, low-carbon solution. One abundant energy source on Earth is solar energy which can be implemented using solar panels which have an established maximum efficiency of 25%, or solar thermal engines which can outperform solar photovoltaic systems by achieving higher efficiencies between 20% and 40% according to market research. Here, an approach to model and quantify the energy efficiency of a direct-drive solar thermal powered batch reverse osmosis system is presented to indicate the feasibility of pursuing this technology. …

Managing Humidity In Electronics Using Water Vapor-Selective Membranes, Songhao Wu, Andrew J. Fix, Allison Mou, David M. Warsinger, James Braun

Discovery Undergraduate Interdisciplinary Research Internship

Abstract: As outdoor electronics have become prevalent in every aspect of daily life, handling humidity in them is an emerging issue for reliable devices. As water vapor enters the electronics enclosure, there is a risk of condensation, which could prevent the electronics from functioning and further damage the device. Traditionally, the humidity removal for electronics is usually done by heating the air within the enclosure, which can be energy-intensive and less efficient. Vapor selective membrane systems are promising alternatives for air heating dehumidification as they do not require heating energy for water vapor removal. It allows water vapor transport through …

Material Synthesis And Additive Manufacturing Of Ceramics, Elsa Bramasco-Rivera

Open Access Theses & Dissertations

This research is divided into two main topics: vitrimer polymers and alumina ceramics. Additive manufacturing is an emerging technology. In this research, two main methods of additive manufacturing are used: material extrusion and vat photopolymerization. The hypothesis of self-healing and mechanochromism functionalities was tested through the synthesis of vitrimers, a novel material combining properties of both thermosets and thermoplastics. These vitrimers were 3D printed using material extrusion. Casted vitrimers showed stiffening effects after submergence in water. Lithography based ceramics have gained attention in recent years due to their wide range of applications. Alumina ceramics were additively manufactured using digital light …

Large Eddy Simulation Of The Wakes Of Three Urban Air Mobility Vehicles, Denis-Gabriel Caprace, Andrew Ning

Faculty Publications

Recent advances in urban air mobility have driven the development of many new VTOL concepts. These vehicles often feature original designs and futuristic shapes. Due to their novelty, the wake characteristics of such aircraft are unknown. However, large wake-induced velocities, should they exist, may be dangerous for any other vehicle evolving in their close proximity. Therefore, improved knowledge about the wakes of VTOL vehicles is needed to guarantee the safety of urban air mobility operations. In this work, we study the wake of three VTOL aircraft in cruise by means of large eddy simulation. We present a two-stage numerical procedure …

Corrosion Assessment Of Biodegradable Metal Implants For Orthopedic Applications, Wendy B. Reynoso-Diaz

Honors Theses

Magnesium alloys are the most promising materials to be used as biodegradable implants mainly due to their superior biocompatibility and lower specific density compared to other biodegradable metals (i.e., zinc and iron-based alloys). This study is investigating the effect of two different manufacturing methods and purity levels on the corrosion rates of a novel Mg-Zn-Ca-Mn-based alloy. Experimental in vitro corrosion tests were conducted on the biocompatible Mg-Zn-Ca-Mn-based alloy fabricated using conventional casting and hot rolling with low and high purity levels. The experimental research conducted, assessed the corrosion rates of the following Mg-1.2Zn-0.5Ca-0.5Mn-based alloys: Hot Rolled High Purity, As-Cast High …

Rheological Behavior Of Dspc-, Dbpc-, And Dppc-Oxygen Microbubbles And Their Effectiveness In Improving Survival In A Rat Model Of Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome, Riaz Ur Rehman Mohammed

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

Acute respiratory distress syndrome (ARDS) causes 75,000 deaths in the U.S., annually. It is characterized by hypoxemia and damage to the lung alveoli. ARDS Management strategies involve extracorporeal membrane oxygenation (ECMO) and mechanical ventilation, but none of these methods improve the mortality rates. Oxygen microbubbles (OMBs) consist of a lipid shell with an oxygen core and have potential to augment oxygenation to manage ARDS. Previous studies demonstrated significant improvements in systemic oxygenation and mortality upon administering OMBs.

We replicated an ARDS rat model by intratracheal administration of lipopolysaccharide at a 24 mg/kg dose. After inducing the disease in rats, the …

Design Of Path Correction For Improved Gait Rehabilitation, Zvonimir Pusnik

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

Following a serious neurological injury or disease, such as a spinal cord injury or multiple sclerosis, many patients develop impaired gait (the ability to walk). There are many different pieces of equipment to help rehabilitate people with impaired gait, ranging from over ground walking with exoskeletons to treadmills with partial bodyweight support. Since the 1990s and 2000s, elliptical trainers have entered the rehabilitative field as a machine with low impact forces and gait-like motion. This led researchers at Madonna Rehabilitation Hospitals to collaborate with the University of Nebraska-Lincoln to create the Intelligently Controlled Assistive Rehabilitation Elliptical (ICARE).

While the ICARE …

Quantifying Shear Stresses In Tissue Engineered Aortic Heart Valves, Raj Nitin Dave

All Theses

Present heart valve prosthesis have limitations such as capability to grow, repair and remodel post implantation. Tissue engineering offers to be a promising alternative to overcome these limitations. Maturation of seeded human cells on the valve subjected to favorable growth conditions in the bioreactor is critical to the success of tissue engineered heart valves. Mechanical stress and strain which results from the pressure and flow conditions in the bioreactor plays a critical role on the developing valve tissue and are currently unknown. The goal of this research is to relate the magnitude of wall shear stress (WSS) within the heart …

Investigating The Effects Of Sic Abrasive Particles On Friction Element Welding, Gaurav Awate

All Theses

The growing demands on reducing the harmful emissions from automobiles have forced automakers to reduce the weight of the vehicle. The increasing demands on improving the fuel economy also has challenged automotive manufacturers to make the vehicle as lightweight as possible. However, the challenge is also to ensure that the vehicle meets safety standards. For the vehicle to meet these standards, it needs to be of adequate strength as well. Automotive manufacturers have adopted a strategy of using multi-material construction to achieve the target. But with multi-material construction comes the requirement of advanced joining techniques that are capable of joining …

An Experimental Analysis Of Thin Sheet Metal Bending By Ultrafast Laser Peen Forming, Bryce J. Tessmann

All Theses

This study demonstrates the viability of femtosecond laser peen forming for bidirectional sheet metal bending. Ultrafast laser forming is a valuable method thanks to its flexibility, negation of springback, no need for a confining or protective layer, and minimalization of thermal degradation in comparison to other forming processes. However, femtosecond lasers have traditionally been believed to be unsuitable for laser forming in comparison to nanosecond lasers, particularly bidirectional bending, because the induced shock waves were expected to be weak. Conversely, in this study it is elucidated that the femtosecond laser-induced shock waves are extremely strong (several hundred GPa) but the …

Examining The Different Snap-Through Characteristics Of Bistable Cfrp Composite Laminates, Vishrut Deshpande

All Theses

Bistable carbon fiber composites, whose bistability arises from having asymmetric fiber layouts in different layers, have shown immense potential for use in shape morphing and adaptive structure applications. While many studies in this field focus on these composite laminates’ external shapes at the two stable states, their snap-through behavior of shifting from one stable shape to the other remains a critical aspect to be investigated in complete detail. Moreover, symmetric loading conditions have been extensively studied based on the classical lamination theory, but the asymmetric loading conditions received far less attention. Therefore, this study examines an asymmetric, localized point load …

Additive Manufacturing Of Variable Contrast Computed Tomography Anatomical Phantoms Using A Single Feedstock In Fused Filament Fabrication, Cory J. Darling

LSU New Orleans Theses and Dissertations

Anatomical phantoms used in biomedical education and training benefit greatly from Fused filament fabrication’s (FFF) ability to rapidly produce complex and unique models. Current materials and methods used in FFF have limited ability to accurately produce phantoms that can mimic the radiological properties of multiple biological tissues. This research demonstrates that the CT contrast of FFF produced models can be modified by varying the concentration of bismuth oxide in acrylonitrile butadiene styrene (ABS) filaments and a tunable CT contrast that mimics the CT contrast ranging from fatty tissue to cortical bone using a single composite filament without introducing artificial image …

Strain-Based Design Of Steel-Polymer-Steel Composite Pipes, Vul Thang

LSU New Orleans Theses and Dissertations

Many offshore single-wall pipelines and structural failures have occurred in the past. As a result, lives were lost, and billions of dollars were spent. In addition, natural disasters such as earthquake fault zones can cause a large volume of soil movement. This can easily damage single-wall pipelines or piles of fixed offshore platforms in the earthquake fault zone.

Currently, the single-wall pipelines are used for the offshore and onshore oil and gas industry. This research investigated the use of double-wall composite pipe steel-polymer-steel (SPS) in place of single-wall pipe to prevent such failures. The double-wall composite pipe has a larger …

Properties Of 25cr7ni Stainless Steel Fabricated Through Laser-Powder Bed Fusion., Arulselvan Arumugham Akilan

Electronic Theses and Dissertations

Stainless steel is a low carbon high alloyed system with higher concentrations of Cr& Ni, which impart high corrosion resistance to them. Alloys with approximately 25% Cr & 7% Ni in their chemical composition are commercially referred to as ‘Super Duplex Stainless Steel’. They have a unique phase composition of approximately 50% ferrite & 50% austenite, yielding a robust combination of high mechanical strength & corrosion resistance. They find extensive interest & application in the fields which demand a longer service life under intense mechanical / corrosive environment such as offshore oil rigs & pipelines in nuclear power plants. Traditional …

Quantum Dynamics Effects On Amplitude-Frequency Response Of Superharmonic Resonance Of Second-Order Of Electrostatically Actuated Nems Circular Plates, Dumitru Caruntu, Julio S. Beatriz

Mechanical Engineering Faculty Publications

This work deals with the effects of Casimir and/or van der Waals forces (quantum dynamics phenomena) on the amplitude-frequency response of the superharmonic resonance of second-order of axisymmetric vibrations of electrostatically actuated nanoelectromechanical systems (NEMS) clamped circular plates. Electrostatic actuation consists of alternating current (AC) voltage of magnitude to produce hardexcitationsandoffrequencynearonefourththenaturalfrequencyoftheclamped circular plate. The intermolecular forces Casimir and van der Waals, damping force, and electrostatic force are the forces acting on the NEMS plate. Six Reduced Order Models (ROMs) with one and up to 6 modes of vibration are used. The ROM with one mode of vibration is solved using …