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Structure, Thermophysical Properties Of Liquids, And Their Connection With Glass Formability, Rongrong Dai 2020 Washington University in St. Louis

Structure, Thermophysical Properties Of Liquids, And Their Connection With Glass Formability, Rongrong Dai

Engineering and Applied Science Theses & Dissertations

Metallic glasses have drawn significant attention due to their unique properties, such as high strength, excellent elastic energy storage capacity, and versatile processability. However, why some liquids can easily form metallic glasses while others donմ is still unclear. Since metallic glasses are formed when liquids are cooled fast enough to bypass crystallization, we hope to better understand glass formation by investigating the structural evolution and thermophysical properties of the liquids as they are cooled toward the glass transition. Multiple molecular dynamics simulations suggest a crossover temperature for the dynamics near the liquidus temperature, which corresponds to the onset of cooperative ...


Development Of Multi-Axial Fatigue Retrofits For Lock Gate Components, Logan Verkamp 2020 University of Arkansas, Fayetteville

Development Of Multi-Axial Fatigue Retrofits For Lock Gate Components, Logan Verkamp

Theses and Dissertations

Lock gates are essential infrastructure components to the United State (US) supply chain. They create large cost savings and environmental benefits when compared with traditional methods of transport (freight and rail). Because of the large quantity of goods and dependence on these shipping chains, the US economy can be drastically affected by an unexpected gate closure. Unfortunately, many lock gates within the US have reached or exceeded their designed life. Due to the intensity of cyclic loads and the environment, fatigue cracks have become a prominent issue. Developed cracks near the pintle region (a joint which the gate rotates and ...


Impact Resistance Of Fiber-Reinforced Composites Using Computational Simulations, Maitham Alabbad 2020 The University of Maine

Impact Resistance Of Fiber-Reinforced Composites Using Computational Simulations, Maitham Alabbad

Electronic Theses and Dissertations

Composite materials are widely used in aerospace, automotive and wind power industries due to their high strength-to-weight and stiffness-to-weight ratios and their improved mechanical properties compared to metals. The damage resistance of composite materials due to low velocity impact depends on fiber breakage, matrix cracking and delamination between the interfaces. In this research, a numerical investigation of low velocity impact response of a multidirectional symmetric carbon-epoxy composite laminate is carried out and presented. Two different finite element models are developed for composite laminates made of non-crimp fabric to investigate their behavior under different levels of impact energy. In the first ...


Nucor Steel Storage Rack Design, Mac Hanson, Hannah Cataldo, Jason Ziganto, Robert Wozek 2020 Olivet Nazarene University

Nucor Steel Storage Rack Design, Mac Hanson, Hannah Cataldo, Jason Ziganto, Robert Wozek

Scholar Week 2016 - present

The goal of this design project was to build effective steel storage racks for Nucor Steel Kankakee. The important criteria that the design team needed to meet was that the rack was adjustable, could fit all of the manufactured products that Nucor makes, and could fit various lengths of product. Nucor needs a new rack system because their current process makes the shipping process very inefficient.


The Effect Of Oxygen On Properties Of Zirconium Metal, Jie ZHAO 2020 University of Massachusetts Amherst

The Effect Of Oxygen On Properties Of Zirconium Metal, Jie Zhao

Doctoral Dissertations

The influence of oxygen on the thermophysical properties of zirconium has been investigated using MSL-EML (Material Science Laboratory Electromagnetic Levitator) on ISS (International Space Station) in collaboration with NASA (National Aeronautics and Space Administration), ESA (European Space Agency), and DLR (German Aerospace Center). Zirconium samples with different oxygen concentrations was subjected to multiple melt cycles during which the thermophysical properties, such as density, viscosity and surface tension, have been measured at various undercooled and superheated temperatures. Also, there are melt cycles for verifying the solidification mechanism. Similar samples were found to show anomalous nucleation of the solid for certain ranges ...


Fatigue Behavior Of An Advanced Melt-Infiltrated Sic/Sic Composite With Environmental Barrier Coating At 1200°C In Air And In Steam, Thaddeus M. Williams 2020 Air Force Institute of Technology

Fatigue Behavior Of An Advanced Melt-Infiltrated Sic/Sic Composite With Environmental Barrier Coating At 1200°C In Air And In Steam, Thaddeus M. Williams

Theses and Dissertations

Advanced aerospace applications such as aircraft turbine engine components, hypersonic flight vehicles, and spacecraft reentry thermal protection systems require structural materials that have superior long-term mechanical properties under high temperature, high pressure, and varying environmental factors, such as moisture. Because of their low density, high strength and fracture toughness at high temperatures SiC fiber-reinforced SiC matrix composites are being evaluated for aircraft engine hot-section components. In these applications the composites will be subjected to various types of mechanical loadings at elevated temperatures in oxidizing environments. Because their constituents are intrinsically oxidation-prone, the most significant problem hindering SiC/SiC composites is ...


Computational Modeling Of Laminated Veneer Bamboo (Lvb) Dowel Joints, Niloufar Khoshbakht 2020 University of Massachusetts Amherst

Computational Modeling Of Laminated Veneer Bamboo (Lvb) Dowel Joints, Niloufar Khoshbakht

Doctoral Dissertations

Laminated veneer bamboo (LVB) is a sustainable building material that has been gaining interest in the construction industry of late. As a relatively new product, little is known about its connection performance, specifically, its failure behavior in dowel type joints and possible similarities it may have to engineered wood products in terms of failure mechanisms. Research is needed to aid in the understanding of LVB dowel connection failure behavior and to quantify the failure mechanism and key factors associated with LVB dowel connection strength. Modeling, as conducted in this research, is a valuable tool to help devise safe standards and ...


Detection Of Surface Cracks In Ferromagnetic Materials By C-Scan Mapping Of Residual Stresses Using Barkhausen Emissions, Neelam Prabhu-Gaunkar, David C. Jiles, G. V. Prabhu Gaunkar 2020 Iowa State University

Detection Of Surface Cracks In Ferromagnetic Materials By C-Scan Mapping Of Residual Stresses Using Barkhausen Emissions, Neelam Prabhu-Gaunkar, David C. Jiles, G. V. Prabhu Gaunkar

Electrical and Computer Engineering Publications

Surface cracks can develop in components due to residual stresses, fatigue, stress corrosion cracking, corrosion fatigue, etc, during service exposure. Different non-destructive testing (NDT) methods are employed to detect and monitor such cracks. Magnetic Barkhausen Noise (MBN) analysis is one such technique that is used for in situ examination of microstructural anomalies or stress patterns. In the present work, we study the applicability of MBN for the detection of surface cracks. A part through surface crack was created by controlled fatigue loading of a martensitic stainless steel plate. The surface of the sample was scanned for BN emissions in incremental ...


Ideal Lacrosse Stick, Josh Beck, Tyler Skoloda, Noah Reed, Stanley Dembosky 2020 The University of Akron

Ideal Lacrosse Stick, Josh Beck, Tyler Skoloda, Noah Reed, Stanley Dembosky

Williams Honors College, Honors Research Projects

This project is focused on the design of a new and innovative lacrosse stick. Our main points of focus will be the strength and durability of the head. As well as solving some of the problems that exist in existing equipment. These problems were identified by interviewing experienced players at the college level. Benefits would include a stronger head that is easier to use for a player on the field to do things like pass, catch, shoot, and field ground balls in an optimal manner. Normally players will have to purchase new heads every season as a result of warping ...


Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications, Hashim Al Mahmud 2020 Michigan Technological University

Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications, Hashim Al Mahmud

Dissertations, Master's Theses and Master's Reports

Significant research effort has been dedicated for decades to improve the mechanical properties of aerospace polymer-based composite materials. Lightweight epoxy-based composite materials have increasingly replaced the comparatively heavy and expensive metal alloys used in aeronautical and aerospace structural components. In particular, carbon fibers (CF)/graphene nanoplatelets (GNP)/epoxy hybrid composites can be used for this purpose owing to their high specific stiffness and strength. Therefore, this work has been completed to design, predict, and optimize the effective mechanical properties of CF/GNP/epoxy composite materials at different length scales using a multiscale modeling approach. The work-flow of modeling involves a ...


Multi-Well Plate Channel Device With Reversible Seals, Haipeng Zhang, Timothy Wei, Sangjin Ryu 2020 University of Nebraska - Lincoln

Multi-Well Plate Channel Device With Reversible Seals, Haipeng Zhang, Timothy Wei, Sangjin Ryu

Mechanical & Materials Engineering Faculty Publications

Atherosclerosis is a cardiovascular disease which causes over 26,000 yearly deaths in the United States. This disease involves accumulation of substances in arterial walls (or plaques) that occurs frequently to arterial regions experiencing low shear stress, such as bends and bifurcations. A possible reason of plaque growth in arterial walls is the change of endothelial cell (EC)’s shape, which is related to fluid shear stresses tangentially acting on intimal layer (the EC surface) of the arterial wall. Lambert et al. studied the relationship between EC shape and shear stress (Lambert et al., 2019) using a BioFlux system (Fluxion ...


Nanothermomechanical And And Or Logic Gates, Ahmed Hamed, Sidy Ndao 2020 University of Nebraska - Lincoln

Nanothermomechanical And And Or Logic Gates, Ahmed Hamed, Sidy Ndao

Mechanical & Materials Engineering Faculty Publications

Today’s electronics cannot perform in harsh environments (e.g., elevated temperatures and ionizing radiation environments) found in many engineering applications. Based on the coupling between near-field thermal radiation and MEMS thermal actuation, we presented the design and modeling of NanoThermoMechanical AND, OR, and NOT logic gates as an alternative, and showed their ability to be combined into a full thermal adder to perform complex operations. in this work, we introduce the fabrication and characterization of the first ever documented Thermal AND and OR logic gates. Theresults show thermal logic operations can be achieved successfully through demonstrated and easy-to- manufacture ...


Three-Dimensional Characterization Of Peripapillary Retinal Pigment Epithelium-Basement Membrane Layer In Patients Following Lumbar Puncture, Junfei Tong, Pengfei Dong, Sachin Kedar, Deepta Ghate, Linxia Gu 2020 University of Nebraska - Lincoln

Three-Dimensional Characterization Of Peripapillary Retinal Pigment Epithelium-Basement Membrane Layer In Patients Following Lumbar Puncture, Junfei Tong, Pengfei Dong, Sachin Kedar, Deepta Ghate, Linxia Gu

Mechanical & Materials Engineering Faculty Publications

Purpose: To develop and test an innovative semi-automatic method for quantifying the three-dimensional morphology of the peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer, with application to lumbar puncture (LP) patients. Methods: Nineteen patients undergoing LP were recruited. The optic nerve head images of both eyes were acquired in 12 radial directions using optical coherence tomography (OCT) before and after LP. For each OCT image, the ppRPE/BM layer was automatically segmented with manual corrections by independent graders when necessary. The linear regression model of the ppRPE/BM layer was fitted using the least squares approach, and the ppRPE/BM ...


Additive Manufacturing Of Magnesium Alloys, Rakeshkumar Karunakaran, Sam Ortgies, Ali Tamayol, Florin Bobaru, Michael P. Sealy 2020 University of Nebraska - Lincoln

Additive Manufacturing Of Magnesium Alloys, Rakeshkumar Karunakaran, Sam Ortgies, Ali Tamayol, Florin Bobaru, Michael P. Sealy

Mechanical & Materials Engineering Faculty Publications

Magnesium alloys are a promising new class of degradable biomaterials that have a similar stiffness to bone, which minimizes the harmful effects of stress shielding. Use of biodegradable magnesium implants eliminates the need for a second surgery for repair or removal. There is a growing interest to capitalize on additive manufacturing's unique design capabilities to advance the frontiers of medicine. However, magnesium alloys are difficult to 3D print due to the high chemical reactivity that poses a combustion risk. Furthermore, the low vaporization temperature of magnesium and common biocompatible alloying elements further increases the difficulty to print fully dense ...


Passivation Of Defects In Perovskite Materials For Improved Solar Cell Efficiency And Stability, Jinsong Huang, Xiaopeng Zheng 2020 Lincoln, NE

Passivation Of Defects In Perovskite Materials For Improved Solar Cell Efficiency And Stability, Jinsong Huang, Xiaopeng Zheng

Mechanical & Materials Engineering Faculty Publications

Semiconductor devices, and methods of forming the same, include a cathode layer, an anode layer, and an active layer disposed between the cathode layer and the anode layer, wherein the active layer includes a perovskite layer. A passivation layer is disposed directly on a surface of the active layer between the cathode layer and the active layer, the passivation layer including a layer of material that passivates both cationic and anionic defects in the surface of the active layer.


Jominy Hardenability Tester With In-Situ Heating, Luke Allen 2020 The University of Akron

Jominy Hardenability Tester With In-Situ Heating, Luke Allen

Williams Honors College, Honors Research Projects

This project centers on building a Jominy Hardenability tester with In-Situ heating for the manufacturing lab at the University of Akron. A new process and setup will be designed using engineering concepts in order to make the testing more efficient and safer for the teaching and testing of metal hardness. The current Jominy testing setup has efficiency issues within the transfer of specimen from induction heater to testing rig. Our design will simplify the design by creating a test rig that removes the traveling aspect of the specimen which will limit the amount of premature cooling done and will be ...


Synthesis And Characterization Of Material Systems For 3d Printed Smart Structures, Hilda Fontes 2020 University of Texas at El Paso

Synthesis And Characterization Of Material Systems For 3d Printed Smart Structures, Hilda Fontes

Open Access Theses & Dissertations

The silica hollow spheres have demonstrated excellent results in multiple applications such as light-weight composites, and optical applications as a glass coating. This material also exhibits excellent thermal, shock impact, and hydrophilic properties extremely useful for industrial applications. However, a controllable size of the particle is desired to further increase the number of applications of the silica hollow spheres.

This Thesis aims a method to fabricate silica hollow spheres in a single step with a controlled diameter size. A study was developed to demonstrate the particle size change when adjusting the molecular weight of the medium by using different alcohol ...


Electrospun Thymosin Beta-4 Loaded Plga/Pla Nanofiber/ Microfiber Hybrid Yarns For Tendon Tissue Engineering Application, Shaohua Wu, Rong Zhou, Fang Zhou, Philipp N. Streubel, Shaojuan Chen, Bin Duan 2020 University of Nebraska Medical Center

Electrospun Thymosin Beta-4 Loaded Plga/Pla Nanofiber/ Microfiber Hybrid Yarns For Tendon Tissue Engineering Application, Shaohua Wu, Rong Zhou, Fang Zhou, Philipp N. Streubel, Shaojuan Chen, Bin Duan

Mechanical & Materials Engineering Faculty Publications

Microfiber yarns (MY) have been widely employed to construct tendon tissue grafts. However, suboptimal ultrastructure and inappropriate environments for cell interactions limit their clinical application. Herein, we designed a modified electrospinning device to coat poly(lactic-co-glycolic acid) PLGA nanofibers onto polylactic acid (PLA) MY to generate PLGA/PLA hybrid yarns (HY), which had a well-aligned nanofibrous structure, resembling the ultrastructure of native tendon tissues and showed enhanced failure load compared to PLA MY. PLGA/PLA HY significantly improved the growth, proliferation, and tendon-specific gene expressions of human adipose derived mesenchymal stem cells (HADMSC) compared to PLA MY. Moreover, thymosin beta-4 ...


3d Printing Of Multilayered Scaffolds For Rotator Cuff Tendon Regeneration, Xiping Jiang, Shaohua Wu, Mitchell Kuss, Yunfan Kong, Wen Shi, Philipp N. Streubel, Tieshi Li, Bin Duan 2020 University of Nebraska Medical Center

3d Printing Of Multilayered Scaffolds For Rotator Cuff Tendon Regeneration, Xiping Jiang, Shaohua Wu, Mitchell Kuss, Yunfan Kong, Wen Shi, Philipp N. Streubel, Tieshi Li, Bin Duan

Mechanical & Materials Engineering Faculty Publications

Repairing massive rotator cuff tendon defects remains a challenge due to the high retear rate after surgical intervention. 3D printing has emerged as a promising technique that enables the fabrication of engineered tissues with heterogeneous structures and mechanical properties, as well as controllable microenvironments for tendon regeneration. In this study, we developed a new strategy for rotator cuff tendon repair by combining a 3D printed scaffold of polylactic-co-glycolic acid (PLGA) with cell-laden collagen-fibrin hydrogels. We designed and fabricated two types of scaffolds: one featuring a separate layer-by-layer structure and another with a tri-layered structure as a whole. Uniaxial tensile tests ...


Imparities Of Shear Avalanches Dynamic Evolution In A Metallic Glass, Yin Du, Qing Zhou, Qian Jia, Yidi Shi, Haifeng Wang, Jian Wang 2020 Northwestern Polytechnical University

Imparities Of Shear Avalanches Dynamic Evolution In A Metallic Glass, Yin Du, Qing Zhou, Qian Jia, Yidi Shi, Haifeng Wang, Jian Wang

Mechanical & Materials Engineering Faculty Publications

The imparities of shear avalanches dynamic evolution under nanoindentation originating from the soft regions and the stiff matrix were explored in a metallic glass by statistical and dynamic analysis. Upon the continuous indentation process, the dynamic state of the stiff matrix exhibits a transition from a chaotic behavior to a self-organized critical (SOC) behavior, whereas the soft regions are domi-nated by the SOC behavior throughout the indentation process. The mechanism was clarified by the evolution of the cut-off size of shear avalanches. These findings might advance our fundamental understanding of inhomogeneous deformation on microscale.

IMPACT STATEMENT The shear avalanches dynamic ...


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