Mechanical Characterizations Of 3d-Printed
Plla/Steel Particle Composites,
2019
University of Nebraska-Lincoln
Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
The objective of this study is to characterize the micromechanical properties of poly-L-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 μm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus of …
Hemodynamic Interference Of Serial Stenoses And Its
Impact On Ffr And Ifr Measurements,
2019
University of Nebraska-Lincoln
Hemodynamic Interference Of Serial Stenoses And Its Impact On Ffr And Ifr Measurements, Siyeong Ju, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
The hemodynamic interference of serial stenoses poses challenges for identifying the functional severity using the fractional flow reserve (FFR) method. The instantaneous wave-free ratio (iFR), i.e., the distal-to-proximal pressure ratio at 75% of diastole, was recently proposed to overcome the disadvantages of the FFR. However, the underlying mechanism remained ambiguous due to the lack of quantitative definition of hemodynamic interference. The objective of this study is to quantitatively define the hemodynamic interference and then examine its role on the FFR and iFR measurements. Pressure distributions, velocity fields, and Q-criterion which identifies vortices, were obtained through the computational fluid dynamics (CFD) …
Hemodynamics And Wall Mechanics After Surgical
Repair Of Aortic Arch: Implication For Better
Clinical Decisions,
2019
University of Nebraska-Lincoln
Hemodynamics And Wall Mechanics After Surgical Repair Of Aortic Arch: Implication For Better Clinical Decisions, Siyeong Ju, Ibrahim Abdullah, Shengmao Lin, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
Graft repair of aortic coarctation is commonly used to mimic the physiological aortic arch shape and function. Various graft materials and shapes have been adopted for the surgery. The goal of this work is to quantitatively assess the impact of graft materials and shapes in the hemodynamics and wall mechanics of the restored aortic arch and its correlation with clinical outcomes. A three-dimensional aortic arch model was reconstructed from magnetic resonance images. The fluid–structure interaction (FSI) analysis was performed to characterize the hemodynamics and solid wall mechanics of the repaired aortic arch. Two graft shapes (i.e., a half-moon shape and …
Interface Facilitated Reorientation Of Mg Nanolayers In Mg-Nb Nanolaminates,
2019
University of Minnesota, Minneapolis
Interface Facilitated Reorientation Of Mg Nanolayers In Mg-Nb Nanolaminates, Y. Chen, Mingyu Gong, N. A. Mara, Jian Wang
Department of Mechanical and Materials Engineering: Faculty Publications
Mg/Nb nanolaminates synthesized through vapor deposition techniques exhibit high flow strength without conventional twinning in Mg. In this work, we investigated the influence of laminated microstructures on deformation mechanisms of Mg nanolayers. Using molecular dynamics simulations, we explored that (0001)-oriented Mg layers transform or re-orient to {10¯10}-oriented Mg layers through nucleation and growth of {10¯12} twins by atomic shuffling, instead of conventional {10¯12} twinning shear. Such a reorientation accommodates in-plane compressive strain and out-of-plane tensile strain when Mg/Nb laminates are subjected to compression parallel to the Mg/Nb interfaces. The nucleation of {10¯12} twins is promoted at the Mg/Nb interface due …
Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers,
2019
University of Nebraska-Lincoln
Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers, Siavash Jafarzadeh, Florin Bobaru, Ziguang Chen
Department of Mechanical and Materials Engineering: Faculty Publications
In this work, the peridynamic corrosion model is used for 3D simulation of pitting corrosion in stainless steel. Models for passivation and salt layer formation are employed to predict detailed characteristics of pit growth kinetic in stainless steels, such as lacy cover formation on top of the pit, and the diffusion-controlled regime at the pit bottom. The model is validated against an experimentally grown pit on 316L stainless steel in NaCl solution. Lacy covers in this model are formed autonomously during the simulation process. They are remarkably similar to the covers observed on top of the real pits.
Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers,
2019
University of Nebraska-Lincoln
Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers, Siavash Jafarzadeh, Florin Bobaru, Ziguang Chen
Department of Mechanical and Materials Engineering: Faculty Publications
In this work, the peridynamic corrosion model is used for 3D simulation of pitting corrosion in stainless steel. Models for passivation and salt layer formation are employed to predict detailed characteristics of pit growth kinetic in stainless steels, such as lacy cover formation on top of the pit, and the diffusion-controlled regime at the pit bottom. The model is validated against an experimentally grown pit on 316L stainless steel in NaCl solution. Lacy covers in this model are formed autonomously during the simulation process. They are remarkably similar to the covers observed on top of the real pits.
Engineering Of Earth-Abundant Electrochemical Catalysts,
2019
Virginia Commonwealth University
Engineering Of Earth-Abundant Electrochemical Catalysts, Dylan D. Rodene
Theses and Dissertations
Alternative energy research into hydrogen production via water electrolysis addresses environmental and sustainability concerns associated with fossil fuel use. Renewable-powered electrolyzers are foreseen to produce hydrogen if energy and cost requirements are achieved. Electrocatalysts reduce the energy requirements of operating electrolyzers by lowering the reaction kinetics at the electrodes. Platinum group metals (PGMs) tend to be utilized as electrocatalysts but are not readily available and are expensive. Ni1-xMox alloys, as low-cost and earth-abundant transition metal nanoparticles (NPs), are emerging as promising electrocatalyst candidates to replace expensive PGM catalysts in alkaline media. Pure-phase cubic and hexagonal Ni1-x …
Costs And Benefits Of Flood Mitigation In Louisiana,
2018
Louisiana State University and Agricultural and Mechanical College
Costs And Benefits Of Flood Mitigation In Louisiana, Arash Taghi Nezhad Bilandi
LSU Doctoral Dissertations
Assessing the costs and benefits of hazard mitigation efforts is an essential component of disaster management, planning, and resilience assessment. These calculations are particularly important in locations vulnerable to multiple hazards with high frequencies, such as coastal Louisiana. This study aims to provide an improved understanding of the costs and benefits of flood mitigation efforts in Louisiana funded by federal government grants between 2005 and 2015. Project data provided by the Governor’s Office of Homeland Security and Emergency Preparedness (GOHSEP) were summarized and missing values were imputed using robust statistical approaches. Elevation project cost was investigated for prediction by statistical …
Simplified Approach For Structural Evaluation Of Flexible Pavements At The Network Level,
2018
University of Texas at Tyler
Simplified Approach For Structural Evaluation Of Flexible Pavements At The Network Level, Mena Souliman, Stefan Romanoschi, Samer Dessouky
Publications
Currently, there are few available simple procedures to identify structurally weak pavement sections utilizing Falling Weight Deflectometer (FWD) data at the network level (e.g., city, state or province). A simple method is required to determine the structural condition of pavement sections that can be directly implemented and automated in current pavement databases. The objective of this research study is to develop a simple analysis method to determine the structural condition of pavement sections utilizing the currently available non-destructive testing (NDT) deflection measurement devices at the network level that can be directly implemented and automated in the database of a typical …
Metal Segregation During The Solidification Of Titanium-Aluminum Alloys For 3d Printing Applications,
2018
Louisiana Tech University
Metal Segregation During The Solidification Of Titanium-Aluminum Alloys For 3d Printing Applications, Jwala Parajuli
Master's Theses
Titanium-Aluminum alloys are one of the widely used alloys in multiple engineering applications. They are highly preferred in Selective Laser Melting (SLM) processes due to their low density, high melting temperature, and good strength. Segregation occurs during the solidification of most alloys and produces a non-uniform distribution of atoms. In SLM, segregation may depict the type of adhesion between the two deposited interfacial layers and the strength between the interphase between an already solidified layer and a new one, and overall, the quality of the printed part. In order to avoid segregation, the understanding of the segregation behavior at atomistic …
Effective Magnetic And Electric Response Of Composite Materials,
2018
Louisiana Tech University
Effective Magnetic And Electric Response Of Composite Materials, Mona Hassan Alsaleh
Doctoral Dissertations
Metamaterials (MMs) are nanocomposite materials consisting of metal-dielectric resonators much smaller in size than the wavelength of the incident light. Common examples of metamaterials are based on split ring resonators (SRRs), parallel wires or strips and fishnet structures. These types of materials are designed and fabricated in order to provide unique optical responses to the incident electromagnetic radiation that are not available in naturally existing materials. The MMs can exhibit unusual properties such as strong magnetism at terahertz (THz) and optical frequencies. Additionally, negative index materials (NIMs) can provide negative index of refraction which can be used in many applications …
System And Methods For Ventilation Through A Body Cavity,
2018
Boulder , CO
System And Methods For Ventilation Through A Body Cavity, Mark A. Borden, Benjamin S. Terry
Department of Mechanical and Materials Engineering: Faculty Publications
A system and methods for the delivery of oxygen through a body cavity of a subject using oxygen microbubbles . Through circulation of oxygen microbubbles through the body cavity , oxygen and carbon dioxide exchange may occur . Overall improvement in extending survival rate time during emergency situations caused by pulmonary or similar oxygen - intake restricting injury and / or failure may be achieved through use of the invented system and methods .
Hemodynamics And Pathology Of An Enlarging Abdominal Aortic Aneurysm Model In Rabbits,
2018
Zhengzhou University & Zhengzhou Central Hospital Affiliated to Zhengzhou University
Hemodynamics And Pathology Of An Enlarging Abdominal Aortic Aneurysm Model In Rabbits, Hongmei Chen, Yonghua Bi, Siyeong Yu, Linxia Gu, Xiaoyan Zhu, Xinwei Han
Department of Mechanical and Materials Engineering: Faculty Publications
Hemodynamics may play an essential role in the initiation and progression of abdominal aortic aneurysm (AAA). We aimed to study the mechanism of self-healing process by the changes of hemodynamics and pathology in an enlarging AAA in rabbits. Seventy-two rabbits were randomly divided into three groups. Rabbits underwent extrinsic coarctation and received a 10-minute elastase incubation in Group A and Group B. Absorbable suture used in Group A was terminated by balloon dilation at week 4. Diameter was measured after 1, 3, 5, and 15 weeks, computational fluid dynamics analysis was performed at week 3 and week 15. Rabbits were …
Techniques To Stimulate And Interrogate Cell–Cell Adhesion Mechanics,
2018
University of Nebraska-Lincoln
Techniques To Stimulate And Interrogate Cell–Cell Adhesion Mechanics, Ruiguo Yang, Joshua A. Broussard, Kathleen J. Green, Horacio D. Espinosa
Department of Mechanical and Materials Engineering: Faculty Publications
Cell–cell adhesions maintain the mechanical integrity of multicellular tissues and have recently been found to act as mechanotransducers, translating mechanical cues into biochemical signals. Mechanotransduction studies have primarily focused on focal adhesions, sites of cell-substrate attachment. These studies leverage technical advances in devices and systems interfacing with living cells through cell–extracellular matrix adhesions. As reports of aberrant signal transduction originating from mutations in cell–cell adhesion molecules are being increasingly associated with disease states, growing attention is being paid to this intercellular signaling hub. Along with this renewed focus, new requirements arise for the interrogation and stimulation of cell–cell adhesive junctions. …
Modeling Sulfate Attack In Modern Concrete For Building Sustainable And Resilient Infrastructure,
2018
Texas A&M University
Modeling Sulfate Attack In Modern Concrete For Building Sustainable And Resilient Infrastructure, Zachary Grasley
Publications
External sulfate attack is a complex phenomenon and is manifested in the form of large expansion, cracking, and spalling depending on the exposure solution and material constituent properties. Several models were developed in the past to demonstrate sulfate attack mechanisms that account for the diffusion of sulfate ions into the porous concrete and the successive deformation triggered by the chemical reaction and precipitation of expansive agents. However, none of these models accounts for the effect of the migration of solvent water from the low solute concentration solution to high solute concentration solution driven by the osmotic pressure. Osmotic pressure is …
Nanoflower-Like Bi2moo6/Ag3po4 In Water Treatment,
2018
University of Nevada, Las Vegas
Nanoflower-Like Bi2moo6/Ag3po4 In Water Treatment, Xavier Morgan-Lange, Jaeyun Moon, Kaleab Ayalew
McNair Poster Presentations
• Environmental issues continue to intensify causing natural resources such as clean water to become increasingly scarce while demand only continues to grow. • Some of the most effective measures taken appear to be bioremediation tactics and their synthetic counterparts. • A critical area of interest are semi-conducting photocatalytic nanomaterials that take advantage of the photo-electric effect and use the introduction of ultra violet (UV) and visible light to induce oxidation and reduction reaction in p-type semiconductors. This results in the decomposition of certain pollutants and/or deactivates certain microbes in water. • These materials have the potential to operate using …
Strong And Tough Continuous Nanofibers,
2018
Lincoln, NE
Strong And Tough Continuous Nanofibers, Yuris Dzenis
Department of Mechanical and Materials Engineering: Faculty Publications
Amethod of fabricating a continuous nanofiber is described . The method includes preparing a solution of one or more polymers and one or more solvents and electrospinning the solution by discharging the solution through one or more liquid jets into an electric field to yield one or more continuous nanofibers . The electrospinning process ( i ) highly orients one or more polymer chains in the one or more continuous nanofibers along a fiber axis of the one or more continuous nanofibers , and ( ii ) suppresses polymer crystallization in the one or more continuous nanofibers . The one …
Development Of Self-Healing Mechanisms For Asphalt Pavements,
2018
Louisiana State University and Agricultural and Mechanical College
Development Of Self-Healing Mechanisms For Asphalt Pavements, Max Abelardo Aguirre Deras
LSU Doctoral Dissertations
Self-healing mechanisms, such as microcapsules or hollow-fibers, filled with an asphalt rejuvenator present an emerging technology that would enhance an asphalt mixture’s resistance to cracking damage caused by vehicular and environmental loading. The objectives of this study were to: (a) Evaluate the effects of asphalt rejuvenators on hot-mix asphalt mixtures in order to test its effects on the fundamental engineering properties of the mixtures at high and intermediate temperatures; (b) Develop a synthesis procedure for production of microcapsules and hollow-fibers containing an asphalt rejuvenator; (c) Evaluate the self-healing efficiency of double-walled microcapsules and hollow-fibers filled with an asphalt rejuvenator, through …
Near-Field Heat Transfer Enabled Nanothermomechanical Memory And Logic Devices,
2018
University of Nebraska-Lincoln
Near-Field Heat Transfer Enabled Nanothermomechanical Memory And Logic Devices, Sidy Ndao, Mahmoud Elzouka
Department of Mechanical and Materials Engineering: Faculty Publications
A thermomechanical memory / logic device is disclosed . In embodiments , the thermomechanical device includes a first thermally controlled terminal ( e . g . , hot terminal ) ; a second thermally controlled terminal ( e . g . , cool terminal / base ) ; a stem or other structure that can be thermally expanded connected to the cool terminal ; and a thermal conductive head coupled to the stem . The head can exchange heat with the hot terminal . The stem and head are between the first thermally controlled terminal and the second thermally controlled …
Prevascularization Of 3d Printed Bone Scaffolds By Bioactive
Hydrogels And Cell Co-Culture,
2018
University of Nebraska Medical Center
Prevascularization Of 3d Printed Bone Scaffolds By Bioactive Hydrogels And Cell Co-Culture, Mitchell Kuss, Shaohua Wu, Ying Wang, Jason B. Untrauer, Wenlong Li, Jung Yul Lim, Bin Duan
Department of Mechanical and Materials Engineering: Faculty Publications
Vascularization is a fundamental prerequisite for large bone construct development and remains one of the main challenges of bone tissue engineering. Our current study presents the combination of 3D printing technique with a hydrogel-based prevascularization strategy to generate prevascularized bone constructs. Human adipose derived mesenchymal stem cells (ADMSC) and human umbilical vein endothelial cells (HUVEC) were encapsulated within our bioactive hydrogels, and the effects of culture conditions on in vitro vascularization were determined. We further generated composite constructs by forming 3D printed polycaprolactone/hydroxyapatite scaffolds coated with cell-laden hydrogels and determined how the co-culture affected vascularization and osteogenesis. It was demonstrated …
