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The Mechanism Of Radiation-Induced Nanocluster Evolution In Oxide Dispersion Strengthened And Ferritic-Martensitic Alloys, Matthew John Swenson 2017 Boise State University

The Mechanism Of Radiation-Induced Nanocluster Evolution In Oxide Dispersion Strengthened And Ferritic-Martensitic Alloys, Matthew John Swenson

Boise State University Theses and Dissertations

The objective of this study is to evaluate the mechanism of irradiation-induced nanoparticle evolution in a model Fe-9%Cr oxide dispersion strengthened steel and commercial ferritic-martensitic alloys HCM12A and HT9. Each alloy is irradiated with Fe2+ ions, protons, or neutrons to doses ranging from 1-100 displacements per atoms at 500°C. The morphology of nanoclusters are characterized using atom probe tomography. The evolution of clusters in each alloy are notably different with each irradiating particle, and the competing effects of ballistic dissolution and radiation-enhanced, diffusion-driven growth are attributed to the respective differences in cluster evolution. A phase evolution model ...


Mitigation And Evaluation Of Alkali-Silica Reaction (Asr) And Freezing And Thawing In Concrete Transportation Structures, Richard Albert Deschenes Jr. 2017 University of Arkansas, Fayetteville

Mitigation And Evaluation Of Alkali-Silica Reaction (Asr) And Freezing And Thawing In Concrete Transportation Structures, Richard Albert Deschenes Jr.

Theses and Dissertations

An evaluation of alkali-silica reaction (ASR) and freezing and thawing (F/T) in concrete transportation structures is presented along with mitigation methods for slowing the rate of deterioration in concrete. A combination of field and laboratory testing confirms ASR deterioration is exacerbated by exposure to F/T. Laboratory testing indicates an aggregate previously deemed inert to ASR, caused ASR deterioration in several concrete pavement and transportation structures. Existing standard test methods deem this aggregate safe for use in concrete. A modified test method shows the concrete can deteriorate rapidly when subjected to cycles of conditions promoting ASR and F/T ...


Optimization Of Concrete Mixtures For Use In Structural Elements, Waleed Almutairi 2017 University of Arkansas, Fayetteville

Optimization Of Concrete Mixtures For Use In Structural Elements, Waleed Almutairi

Theses and Dissertations

Portland cement is an essential ingredient in concrete. The use of cement is to enhance the strength as well as other hardened properties of concrete mixtures. Determining the accurate amount of cement is important because the required strength may not be achieved if not enough cement is used. By contrast, when using too much cement, concrete cracking may occur that leads to reducing durability. Researchers at the University of Arkansas (UA) have shown that many bridge decks achieve their 28 day design strength of 4000 psi by 7 days of age. Bridge decks having high strength may experience cracking, which ...


Deformation Behavior Of Al/A-Si Core-Shell Nanostructures, Robert Andrew Fleming 2017 University of Arkansas, Fayetteville

Deformation Behavior Of Al/A-Si Core-Shell Nanostructures, Robert Andrew Fleming

Theses and Dissertations

Al/a-Si core-shell nanostructures (CSNs), consisting of a hemispherical Al core surrounded by a hard shell of a-Si, have been shown to display unusual mechanical behavior in response to compression loading. Most notably, these nanostructures exhibit substantial deformation recovery, even when loaded much beyond the elastic limit. Nanoindentation measurements revealed a unique mechanical response characterized by discontinuous signatures in the load-displacement data. In conjunction with the indentation signatures, nearly complete deformation recovery is observed. This behavior is attributed to dislocation nucleation and annihilation events enabled by the 3-dimensional confinement of the Al core. As the core confinement is reduced, either ...


A Large-Area Strain Sensing Technology For Monitoring Fatigue Cracks In Steel Bridges, Xiangxiong Kong, Jian Li, William Collins, Caroline Bennett, Simon Laflamme, Hongki Jo 2017 University of Kansas

A Large-Area Strain Sensing Technology For Monitoring Fatigue Cracks In Steel Bridges, Xiangxiong Kong, Jian Li, William Collins, Caroline Bennett, Simon Laflamme, Hongki Jo

Civil, Construction and Environmental Engineering Publications

This paper presents a novel large-area strain sensing technology for monitoring fatigue cracks in steel bridges. The technology is based on a soft elastomeric capacitor (SEC), which serves as a flexible and large-area strain gauge. Previous experiments have verified the SEC's capability to monitor low-cycle fatigue cracks experiencing large plastic deformation and large crack opening. Here an investigation into further extending the SEC's capability for long-term monitoring of fatigue cracks in steel bridges subject to traffic loading, which experience smaller crack openings. It is proposed that the peak-to-peak amplitude (pk–pk amplitude) of the sensor's capacitance measurement ...


Synthesis,Structure And Properties Of Ruthenium Polypyridyl Metalloligand Based Metal-Organic Frameworks, Mamatha Polapally 2017 Western Kentucky University

Synthesis,Structure And Properties Of Ruthenium Polypyridyl Metalloligand Based Metal-Organic Frameworks, Mamatha Polapally

Masters Theses & Specialist Projects

Metal-organic frameworks (MOFs) have been extensively studied because of their amazing applications in gas storage, purification, photocatalysis, chemical sensing, and imaging techniques. Ruthenium polypyridyl complexes have been broadly considered as photosensitizers for the conversion of solar energy and photoelectronic materials. With this aspect, we have synthesized three new ruthenium polypyridyl based MOFs ([Ru(H2bpc)Cu(bpc)(Hbpc)2(H2O)]·5H2O (1), [Ru(H2bpc)(Fe(bpc)(Hbpc)2(H2O)2]·6H2O (2) and [Ru(H2bpc)Ni(bpc)(Hbpc)2(H2O)2]·6H2O (3)) from ruthenium(III) chloride, bpc (2,2’- bipyridine-4,4’-dicarboxylic acid) ligand, and 3d M(II) metal ions ...


A Study In The Use Of Elastic Materials In Expandable Containment Units, Andrew J. Eisenman, Joby Anthony III, David Satagaj 2017 Liberty University

A Study In The Use Of Elastic Materials In Expandable Containment Units, Andrew J. Eisenman, Joby Anthony Iii, David Satagaj

Montview Liberty University Journal of Undergraduate Research

The rigidity of materials in conjunction with the aspect of elasticity has been a concern of modern technologies and construction in recent centuries because of the advantages that expandable storage would bring to the fields of containment units with respect to population growth and space exploration. The world population is currently growing at an exponential rate, and as our population grows, the more important it will become to have containment units that can both contain large volumes of material as well as minuscule amounts of material without wasting space. In order accomplish this, we will need a new type of ...


Characterization Of Slm Printed 316l Stainless Steel And Investigation Of Microlattice Geometry, Finley H. Marbury 2017 California Polytechnic State University, San Luis Obispo

Characterization Of Slm Printed 316l Stainless Steel And Investigation Of Microlattice Geometry, Finley H. Marbury

Materials Engineering

The goal of this project was firstly to characterize Cal Poly’s SLM printed 316L stainless steel. SEM analysis showed Cal Poly’s as-printed 316L material to have a cellular dendritic microstructure containing mostly austenite and a small amount of δ-ferrite. After being heat treated to eliminate warp, its yeild and ultimate tensile strength were on par with the literature, however higher modulus and lower elongation were observed. XRD analysis confirmed residual stresses in the material, and that grains are preferentially oriented in both heat treated and non heat treated samples. The amount of porosity in the material was found ...


Development Of Low Cost Braze Alloys For Aerospace Applications, Alyssa M. Elliott, Sandy Babich, Blake Whitmee 2017 California Polytechnic State University, San Luis Obispo

Development Of Low Cost Braze Alloys For Aerospace Applications, Alyssa M. Elliott, Sandy Babich, Blake Whitmee

Materials Engineering

Non-precious metal braze alloys can help lower the cost of brazing, which is a commonly-used joining process in the aerospace industry. A-286, a stainless steel superalloy, and Inconel© 718, a nickel-based superalloy, are both commonly used alloys at Aerojet Rocketdyne. Both alloys were brazed into butt joints using nickel-based braze alloys: AMS 4776, 4777, and 4778. The brazed samples were machined into a modified version of the ASTM E8 subsize specimen samples and tensile tested to compare the strength and calculated elongation of the brazed samples to the base metals’ properties. All of the brazed samples fractured at the joint ...


Bear Minimum: Ultralight Composite Bear Canister, Rama B. Adajian, Adam C. Eisenbarth 2017 California Polytechnic State University, San Luis Obispo

Bear Minimum: Ultralight Composite Bear Canister, Rama B. Adajian, Adam C. Eisenbarth

Mechanical Engineering

The ultralight backpacking community needs a strong, easy to use, safe bear canister that is lighter than current market products for trekking in the backcountry. A full design of the lid for the bear canister is to be completed. This includes the locking mechanism to ensure it is bear proof, the interface between the lid and the canister, and the structure of the lid so it passes the strength and weight specifications. The lid, along with the already designed canister body, is to be manufactured with formal documentation. The lid will initially be tested separately and then with the canister ...


Invariant-Based Method For Improving Efficiency Of Mechanical Testing In Aerospace Certification Of Carbon Fiber-Epoxy Composites, Alyssa Rina Gruezo, Erika Gabrielle Hansen 2017 California Polytechnic State University, San Luis Obispo

Invariant-Based Method For Improving Efficiency Of Mechanical Testing In Aerospace Certification Of Carbon Fiber-Epoxy Composites, Alyssa Rina Gruezo, Erika Gabrielle Hansen

Materials Engineering

The current challenge with qualification of carbon fiber composites in the aerospace industry would be the low efficiency of testing hundreds of samples. The Trace Theory strives to streamline the qualification process by utilizing a material’s Trace to predict properties of composites using Excel programs and basis data. To test this theory, predicted properties from the program, QuickLam, were compared to experimental data. Unidirectional 0° (T1), unidirectional 90° (T2), quasi-isotropic (T3), and hard quasi-isotropic (T4) laminates were made using HexTowR carbon fiber and TC250 resin provided by TenCate Advanced Composites. Tensile and compression tests were done according to ASTM ...


Investigating The Classical And Non-Classical Mechanical Properties Of Gan Nanowires, Mohammad Reza Zamani Kouhpanji 2017 University of New Mexico

Investigating The Classical And Non-Classical Mechanical Properties Of Gan Nanowires, Mohammad Reza Zamani Kouhpanji

Electrical and Computer Engineering ETDs

Study and prediction of classical and non-classical mechanical properties of GaN is crucial due to the potential application of GaN nanowires (NWs) in piezoelectric, probe-based nanometrology, and nanolithography areas. GaN is mainly grown on sapphire substrates whose lattice constant and thermal expansion coefficient are significantly different from GaN. These discrepancies cause mechanical defects and high residual stresses and strains in GaN, which reduce its quantum efficiency.

Specifically, for nanoscale applications, the mechanical properties of materials differ significantly compared to the bulk properties due to size-effects. Therefore, it is essential to investigate the mechanical properties of GaN NWs using the non-classical ...


Study Of Knowledge-Based System (Kbs) And Decision Making Methodologies In Materials Selection For Lightweight Aircraft Metallic Structures, Pashupati R. Adhikari, Reza Mirshams 2017 University of North Texas

Study Of Knowledge-Based System (Kbs) And Decision Making Methodologies In Materials Selection For Lightweight Aircraft Metallic Structures, Pashupati R. Adhikari, Reza Mirshams

Journal of Applied Science & Engineering Technology

This paper presents an overview of knowledge-based system (KBS) in the context of decision making methodologies used in materials selection for the design of light weight aircraft metallic structures. Overall aircraft weight reduction means substantially less fuel consumption and better efficiency. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures in the aircraft. Two distinct multiple criteria decision making (MCDM) methodologies are presented with examples featuring a set of short-listed materials suitable in the design of the structures. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes satisfying ...


Deposition Velocity Dependence On Urban Morphology, Rawand Muzafar Rasheed 2017 Portland State University

Deposition Velocity Dependence On Urban Morphology, Rawand Muzafar Rasheed

Undergraduate Research & Mentoring Program

Understanding the interactions between the atmospheric boundary layer and urban structures provides insights into emerging problems such as green building design as well as dispersion and deposition of pollutants on urban structures. Characterization of deposition velocity dependence through the naphthalene sublimation method on model urban structures is conducted herein where the analogous fundamental transport mechanisms of momentum and mass transport is obtained via mass of naphthalene transferred. Via wind tunnel experiments, results show that deposition velocity of naphthalene from urban structures increases with increased number of urban structures ahead of the point of investigation. This is attributed to the wakes ...


Effect Of Chain Rigidity On Network Architecture And Deformation Behavior Of Glassy Polymer Networks, Kyler Reser Knowles 2017 University of Southern Mississippi

Effect Of Chain Rigidity On Network Architecture And Deformation Behavior Of Glassy Polymer Networks, Kyler Reser Knowles

Dissertations

Processing carbon fiber composite laminates creates molecular-level strains in the thermoset matrix upon curing and cooling which can lead to failures such as geometry deformations, micro-cracking, and other issues. It is known strain creation is attributed to the significant volume and physical state changes undergone by the polymer matrix throughout the curing process, though storage and relaxation of cure-induced strains remain poorly understood. This dissertation establishes two approaches to address the issue. The first establishes testing methods to simultaneously measure key volumetric properties of a carbon fiber composite laminate and its polymer matrix. The second approach considers the rigidity of ...


Experimental And Computational Investigation Of High Entropy Alloys For Elevated-Temperature Applications, Haoyan Diao 2017 University of Tennessee, Knoxville

Experimental And Computational Investigation Of High Entropy Alloys For Elevated-Temperature Applications, Haoyan Diao

Doctoral Dissertations

To create and design novel structural materials with enhanced creep-resistance, fundamental studies have been conducted on high-entropy alloys (HEAs), using (1) thermodynamic calculations, (2) mechanical tests, (3) neutron diffraction, (4) characterization techniques, and (5) crystal-plasticity finite-element modeling (CPFEM), to explore future candidates for next-generation power plants.

All the constituent binary and ternary systems of the Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr- Fe-Ni systems were thermodynamically modeled within the whole composition range. Comparisons between the calculated phase diagrams and literature data are in good agreement. The AlxCrCuFeMnNi HEAs have disordered [face-centered-cubic (FCC) + body-centered-cubic (BCC)] crystal structures. Excessive alloying of the Al element ...


Multifunctional Transition Metal Oxide Core Shell Magnetic Nanoparticles, Mahmud Reaz 2017 Missouri State University

Multifunctional Transition Metal Oxide Core Shell Magnetic Nanoparticles, Mahmud Reaz

MSU Graduate Theses

Oxide core-shell nanoparticles (CSNPs) have attracted considerable interest for their multifunctional properties. Luminescent ZnO, ferroelectric BaTiO3, and inverse spinel iron oxide can be exploited to develop magneto-luminescent and multiferroic nanomaterials. The novel sonochemical method has been used to synthesize the nanomaterials. Atomic-scale spectroscopy establishes the core-shell nature and multifunctional properties of the nanomaterials. Magnetic hysteresis (coercivity, remnant, and saturation magnetization) and temperature dependent data indicate the key structural difference between the oxidized and reduced ZnO/iron oxide CSNPs. Variation in the coercive field and remnant and saturation magnetization further confirms the presence of different iron oxides in the shell region ...


Analysis Of Tool Wear And Tool Life Of Cutting Tool Inserts Using Statistical Process Control Charts: A Case Study, Evan R. Ferrell 2017 Morehead State University

Analysis Of Tool Wear And Tool Life Of Cutting Tool Inserts Using Statistical Process Control Charts: A Case Study, Evan R. Ferrell

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Business and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Evan R. Ferrell on April 28, 2017.


Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das 2017 University of Nebraska-Lincoln

Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

No abstract provided.


Sub-4 Nm Ptzn Intermetallic Nanoparticles For Enhanced Mass And Specific Activities In Catalytic Electrooxidation Reaction, Zhiyuan Qi, Chaoxian Xiao, Cong Liu, Tian Wei Goh, Lin Zhou, Raghu V. Maligal-Ganesh, Yuchen Pei, Xinle Li, Larry A. Curtiss, Wenyu Huang 2017 Iowa State University

Sub-4 Nm Ptzn Intermetallic Nanoparticles For Enhanced Mass And Specific Activities In Catalytic Electrooxidation Reaction, Zhiyuan Qi, Chaoxian Xiao, Cong Liu, Tian Wei Goh, Lin Zhou, Raghu V. Maligal-Ganesh, Yuchen Pei, Xinle Li, Larry A. Curtiss, Wenyu Huang

Chemistry Publications

Atomically ordered intermetallic nanoparticles (iNPs) have sparked considerable interest in fuel cell applications by virtue of their exceptional electronic and structural properties. However, the synthesis of small iNPs in a controllable manner remains a formidable challenge because of the high temperature generally required in the formation of intermetallic phases. Here we report a general method for the synthesis of PtZn iNPs (3.2 ± 0.4 nm) on multiwalled carbon nanotubes (MWNT) via a facile and capping agent free strategy using a sacrificial mesoporous silica (mSiO2) shell. The as-prepared PtZn iNPs exhibited ca. 10 times higher mass activity in both acidic ...


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