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Studies On Stable Crack Growth, Mohammed Juma Humaid Al-Ghafri 2017 United Arab Emirates University

Studies On Stable Crack Growth, Mohammed Juma Humaid Al-Ghafri

Theses

The goal of this work is to experimentally investigate the stable crack growth (SCG) fracture behavior of AISI 4340 alloy steel. A series of mode I and mixed mode SCG fracture tests were carried out on 8 mm thick compact tension (CT) specimens subjected to quasistatic loading. The wire cutting technique was used to introduce a pre-notch/ pre-crack of 0.05 mm root radius to the specimen. Five different loading angles Ψ between the loading axis and the crack surface were employed; 90° (mode I), 75°, 65°, 60° and 50°. Five different ratios of original crack length to specimen width ...


Simulations Of A New Continuous Steelmaking Process, Jorg Annie Peter, Kent D. Peaslee, D. G. C. Robertson 2017 Missouri University of Science and Technology

Simulations Of A New Continuous Steelmaking Process, Jorg Annie Peter, Kent D. Peaslee, D. G. C. Robertson

D. G. C. Robertson

A new continuous steelmaking process has been designed in an effort to reduce meltshop costs and increase productivity beyond the possibilities of current EAF-LMF-CC meltshops. This paper discusses possible operational performance based on industrially-verified kinetic, thermodynamic, and heat-transfer models. Dynamic simulations predict variations in steel chemistry and temperature, resulting from steel treatment and upsets. Savings in costs are projected because of increased metallic yield, lower energy requirements, more efficient use of deoxidants and alloys, fewer man-hours per ton, and decreased capital investment.


Simple Apparatus For Producing Single Liquid Drops, Dhiren Panda, D. G. C. Robertson 2017 Missouri University of Science and Technology

Simple Apparatus For Producing Single Liquid Drops, Dhiren Panda, D. G. C. Robertson

D. G. C. Robertson

A simple experimental apparatus has been used to produce individual mercury and sodium amalgam drops in the size range of 0.3-2.5 mm diam. A high resistance to the flow of liquid was provided by a capillary tube. The cross section consisted of a 0.20 mm o.d. tungsten wire placed in a 0.25 mm capillary bore. By this method, flow rates of 1 μl/s and lower were obtained, which enabled the formation of drops as small as 1 mm diam in a time interval of 20 s. The drops were formed at a plastic tip ...


Detection Of 4-Point Bend Induced Micro-Cracks In Cfrp Laminates Via Coda Wave Nde, Richard Livings, Dan Barnard, Vinay Dayal 2017 Iowa State University

Detection Of 4-Point Bend Induced Micro-Cracks In Cfrp Laminates Via Coda Wave Nde, Richard Livings, Dan Barnard, Vinay Dayal

Vinay Dayal

Although coda wave NDE has been shown to have some sensitivity to realistic damage in concrete structures, the technique’s capability for detecting micro-cracks in fibrous composite materials has yet to be evaluated. This paper reports on the first investigation of realistic damage, specifically micro-cracks, in fibrous composite materials using coda wave differential signal features. Micro-cracks were generated in CFRP samples using the 4-point bending configuration shown in Fig. 1. The damage was monitored during loading with Acoustic Emission, and the loading was stopped after each significant damage event. The damage was then examined with coda wave NDE, immersion UT ...


Development Of Starch-Polyvinyl Alcohol (Pva) Biodegradable Film: Effect Of Cross-Linking Agent And Antimicrobials On Film Characteristics, Aniket Satish More, Chandani Sen, Madhusweta Das 2017 Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur

Development Of Starch-Polyvinyl Alcohol (Pva) Biodegradable Film: Effect Of Cross-Linking Agent And Antimicrobials On Film Characteristics, Aniket Satish More, Chandani Sen, Madhusweta Das

Journal of Applied Packaging Research

To satisfy the need of developing eco-friendly flexible antimicrobial packaging film with minimum use of synthetic chemical ingredients, the present study examined the efficacy of citric acid (CA) as cross-linking agent and essential oils (EOs), viz., cinnamon essential oil (CEO) and oregano essential oil (OEO) as natural antimicrobials in corn starch-polyvinyl alcohol (CS-PVA) film. Compared to film prepared from filmogenic solution (FS) containing 75 kg CS+8.75 kg PVA+24.6 kg glycerol per m3 FS, film additionally containing CA at 0.07 kg/kg CS indicated 95% higher ultimate tensile strength (UTS) and 27% lower water vapor ...


Ionic Liquid‐Assisted Microwave Synthesis Of Solid Solutions Of Perovskite Sr1‐Xbaxsno3 For Photocatalytic Applications, Tarek Alammar, Igor Slowing, Jim Anderegg, Anja Mudring 2017 Iowa State University

Ionic Liquid‐Assisted Microwave Synthesis Of Solid Solutions Of Perovskite Sr1‐Xbaxsno3 For Photocatalytic Applications, Tarek Alammar, Igor Slowing, Jim Anderegg, Anja Mudring

Igor I. Slowing

Nanocrystalline Sr1−xBaxSnO3 (x=0, 0.2, 0.4, 0.8, 1) perovskite photocatalysts were prepared by microwave synthesis in an ionic liquid (IL) and subsequent heat-treatment. The influence of the Sr/Ba substitution on the structure, crystallization, morphology, and photocatalytic efficiency was investigated and the samples were fully characterized. On the basis of X-ray diffraction results, as the Ba content in the SrSnO3 lattice increases, a symmetry increase was observed from the orthorhombic perovskite structure for SrSnO3 to the cubic BaSnO3 structure. The analysis of the sample morphology by SEM reveals that the Sr1−xBaxSnO3 samples favor the formation ...


Nonlinear Optical Studies Of Defects And Domain Structures In Perovskite-Type Dielectric Ceramics, David J. Ascienzo 2017 The Graduate Center, City University of New York

Nonlinear Optical Studies Of Defects And Domain Structures In Perovskite-Type Dielectric Ceramics, David J. Ascienzo

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

In order to improve future generations of dielectric capacitors a deeper understanding of voltage-induced dielectric breakdown and electrical energy storage limitations is required. This dissertation presents the use of far-field optical second harmonic generation (SHG) polarimetry for probing structural defects and polar domains in linear and nonlinear perovskite dielectric ceramics. We investigated the formation of electric field-induced structural distortions at pristine Fe-doped SrTiO3 (Fe:STO) electrode interfaces, structural defect and strain formation due to oxygen vacancy migration in electrodegraded Fe:STO single crystals, and mixed tetragonal and rhombohedral phase domains in ferroelectric Zr-doped BaTiO3 (BZT) films ...


Effects Of Lignin As A Stabilizer Or Antioxidant In Polyolefins, Afsana S. Kabir 2017 The University of Western Ontario

Effects Of Lignin As A Stabilizer Or Antioxidant In Polyolefins, Afsana S. Kabir

Electronic Thesis and Dissertation Repository

Lignin, a major component of biomass, is an attractive alternative to hindered phenol-based antioxidants for polymers due to its renewable nature and naturally occurring hindered phenolic structure. In this study, for the first time, lignin de-polymerization was explored as a promising approach to improve the reactivity of the lignin-based antioxidants for polymers (polyethylene, PE and polypropylene, PP). A proprietary hydrolytic de-polymerization process was utilized to increase the antioxidant activity of two types of technical lignin: kraft lignin, KL (a by-product from the pulp and paper industry) and hydrolysis lignin, HL (a by-product from the pre-treatment processes in cellulosic ethanol plants ...


58th Annual Rocky Mountain Conference On Magnetic Resonance, 2017 University of Denver

58th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 58th annual meeting of the Rocky Mountain Conference on Magnetic Resonance, co-endorsed by the Colorado Section of the American Chemical Society and the Society for Applied Spectroscopy. Held in Breckenridge, Colorado, July 17-21, 2016.


57th Annual Rocky Mountain Conference On Magnetic Resonance, 2017 University of Denver

57th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 57th annual meeting of the Rocky Mountain Conference on Magnetic Resonance, co-endorsed by the Colorado Section of the American Chemical Society and the Society for Applied Spectroscopy. Held in Snowbird, Utah, July 26-31, 2015.


56th Annual Rocky Mountain Conference On Magnetic Resonance, 2017 University of Denver

56th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 56th annual meeting of the Rocky Mountain Conference on Magnetic Resonance, co-endorsed by the Colorado Section of the American Chemical Society and the Society for Applied Spectroscopy. Held in Copper Mountain, Colorado, July 13-17, 2014.


Systematic Assessment Of The Influence Of Mo Concentration On The Oxygen Ingress In Ti–Mo System During High Temperature Oxidation, P. Samimi, D.A. Brice, Iman Ghamarian, Yue Liu, Peter C. Collins 2017 Iowa State University

Systematic Assessment Of The Influence Of Mo Concentration On The Oxygen Ingress In Ti–Mo System During High Temperature Oxidation, P. Samimi, D.A. Brice, Iman Ghamarian, Yue Liu, Peter C. Collins

Peter Collins

To understand the role of composition in the oxidation behavior of Ti–Mo system and to evaluate the extent of oxygen ingress into the metal substrate during high temperature exposure, a compositionally graded Ti–xMo specimen (0 ≤ x ≤ 12 wt% Mo) was prepared using an additive manufacturing technique, solutionized and then subjected to oxidation tests at 650 °C for different exposure times. The depth of oxygen diffusion, across the composition range, was assessed via change in the local hardness and the results were coupled with quantitative measurement of the oxygen concentration. The concentration of O in the α phase was ...


Characterizing The Nano-Structure And Defect Structure Of Nano-Scaled Non-Ferrous Structural Alloys, Iman Ghamarian, Peyman Samimi, Yue Liu, Behrang Poorganji, Vijay K. Vasudevan, Peter C. Collins 2017 Iowa State University

Characterizing The Nano-Structure And Defect Structure Of Nano-Scaled Non-Ferrous Structural Alloys, Iman Ghamarian, Peyman Samimi, Yue Liu, Behrang Poorganji, Vijay K. Vasudevan, Peter C. Collins

Peter Collins

The presence and interaction of nanotwins, geometrically necessary dislocations, and grain boundaries play a key role in the mechanical properties of nanostructured crystalline materials. Therefore, it is vital to determine the orientation, width and distance of nanotwins, the angle and axis of grain boundary misorientations as well as the type and the distributions of dislocations in an automatic and statistically meaningful fashion in a relatively large area. In this paper, such details are provided using a transmission electron microscope-based orientation microscopy technique called ASTAR™/precession electron diffraction. The remarkable spatial resolution of this technique (~ 2 nm) enables highly detailed characterization ...


A Constitutive Equation Relating Composition And Microstructure To Properties In Ti-6al-4v: As Derived Using A Novel Integrated Computational Approach, Iman Ghamarian, P. Samimi, Vikas Dixit, Peter C. Collins 2017 University of North Texas

A Constitutive Equation Relating Composition And Microstructure To Properties In Ti-6al-4v: As Derived Using A Novel Integrated Computational Approach, Iman Ghamarian, P. Samimi, Vikas Dixit, Peter C. Collins

Peter Collins

While it is useful to predict properties in metallic materials based upon the composition and microstructure, the complexity of real, multi-component, and multi-phase engineering alloys presents difficulties when attempting to determine constituent-based phenomenological equations. This paper applies an approach based upon the integration of three separate modeling approaches, specifically artificial neural networks, genetic algorithms, and Monte Carlo simulations to determine a mechanism-based equation for the yield strength of α+βprocessed Ti-6Al-4V (all compositions in weight percent) which consists of a complex multi-phase microstructure with varying spatial and morphological distributions of the key microstructural features. Notably, this is an industrially important ...


Developing A Phenomenological Equation To Predict Yield Strength From Composition And Microstructure In Β Processed Ti-6al-4v, Iman Ghamarian, B. Hayes, Peyman Samimi, B.A. Welk, H.L. Fraser, Peter C. Collins 2017 Iowa State University

Developing A Phenomenological Equation To Predict Yield Strength From Composition And Microstructure In Β Processed Ti-6al-4v, Iman Ghamarian, B. Hayes, Peyman Samimi, B.A. Welk, H.L. Fraser, Peter C. Collins

Peter Collins

A constituent-based phenomenological equation to predict yield strength values from quantified measurements of the microstructure and composition of β processed Ti-6Al-4V alloy was developed via the integration of artificial neural networks and genetic algorithms. It is shown that the solid solution strengthening contributes the most to the yield strength (~80% of the value), while the intrinsic yield strength of the two phases and microstructure have lower effects (~10% for both terms). Similarities and differences between the proposed equation and the previously established phenomenological equation for the yield strength prediction of the α+β processed Ti-6Al-4V alloys are discussed. While the ...


On The Influence Of Alloy Composition On The Oxidation Performance And Oxygen-Induced Phase Transformations In Ti–(0–8) Wt%Al Alloys, P. Samimi, D.A. Brice, R. Banerjee, M.J. Kaufman, Peter C. Collins 2017 Iowa State University

On The Influence Of Alloy Composition On The Oxidation Performance And Oxygen-Induced Phase Transformations In Ti–(0–8) Wt%Al Alloys, P. Samimi, D.A. Brice, R. Banerjee, M.J. Kaufman, Peter C. Collins

Peter Collins

Adopting a high-throughput combinatorial approach, a compositionally graded Ti–xAl (0 ≤ x ≤ 8 wt%) specimen was prepared to conduct a rapid systematic investigation of the influence of composition and exposure time on the oxidation performance of the titanium-rich section of the binary Ti–Al system. The compositionally graded specimen was solution heat treated and subjected to oxidation tests at 650 °C for different exposure times. The morphology, structure, and composition of the oxide scale as well as the microstructural changes in the base material were studied across the entire composition range, using a suite of characterization techniques. The observations ...


Additive Manufacturing Process Of 3d Polyaniline Transducers Via Direct Ink Writing, Frederick Benjamin Holness 2017 The University of Western Ontario

Additive Manufacturing Process Of 3d Polyaniline Transducers Via Direct Ink Writing, Frederick Benjamin Holness

Electronic Thesis and Dissertation Repository

Electroactive polymers exhibit a change in properties, typically size or shape, in response to electrical stimuli. One class of electroactive polymer of particular interest are the conjugated polymers, whose conjugated backbone structure imparts electrical conductivity. However, this structure imposes processing limitations restricting their form to 2D structures. To overcome this, we develop specially formulated polyaniline- based blends via counter-ion induced thermal doping for the fabrication of 3D conductive structures via direct ink writing. This approach employs multi-material extrusion for the production of structures with passive and active features, rapid device fabrication, and improved design freedom. A model of the thermal ...


Fifty-Plus-Year Postflight Analysis Of First Fluid Experiment Aboard A Spacecraft, Mark M. Weislogel, Yongkang Chen, William J. Masica, Fred J. Kohl, Robert D. Green 2017 Portland State University

Fifty-Plus-Year Postflight Analysis Of First Fluid Experiment Aboard A Spacecraft, Mark M. Weislogel, Yongkang Chen, William J. Masica, Fred J. Kohl, Robert D. Green

Mark M. Weislogel

This year marks the 55th anniversary of the first fluid physics experiment performed aboard a spacecraft during the Mercury-Atlas 7 mission. Since then, NASA has conducted over 80 fluids physics experiments aboard a variety of spacecraft, many of which have enhanced the understanding of large-length-scale capillary phenomena relevant to liquid management in the weightless state. As both celebration and demonstration, the Mercury-Atlas 7 fluids experiment is revisited in light of the current understanding of large-length-scale capillary fluidics. Employing a modern numerical tool, a rich variety of experimental outcomes are discovered that were not observed during the flight experiment. Interestingly, experimental ...


Plasticization And Reinforcement In A Boron Cage Compound Polyurethane Nanocomposite: A Dielectric Study, J. Liu, X. Zhang, D. E. Bowen, Nicola Bowler 2017 Iowa State University

Plasticization And Reinforcement In A Boron Cage Compound Polyurethane Nanocomposite: A Dielectric Study, J. Liu, X. Zhang, D. E. Bowen, Nicola Bowler

Nicola Bowler

In order to control and modify the physical properties of nanocomposite systems, it is essential to understand the nano-filler/polymer structure–property relationships. Boron cage compounds (BCCs) are a class of icosahedral, closed cage molecules that are of interest due to their high boron content, their inherent neutron absorbing/shielding properties, their potential ability to act as molecular nano-particles and their ability to significantly improve the thermal stability of polymers in which they have been incorporated. When the BCC n-hexylcarborane is blended with a polybutadiene (PBD)/polyurethane (PU) segmented copolymer (EN8) an increase in the glass transition (Tg) temperature of ...


Single-Step, Atmospheric Pressure Chemical Vapor Deposition Of Methylammonium Bismuth Iodide Thin Films, Xiao Chen 2017 Washington University in St. Louis

Single-Step, Atmospheric Pressure Chemical Vapor Deposition Of Methylammonium Bismuth Iodide Thin Films, Xiao Chen

Engineering and Applied Science Theses & Dissertations

Lead halide perovskites (CH3NH3PbI3 and its variants) are promising solar cell absorber materials. Though the reported power conversion efficiencies of lead halide perovskite solar cells (up to 21%) are competitive with commercial silicon solar cells, lead toxicity in these perovskites present a challenge to further scale-up and eventual commercialization. Recently, bismuth (Bi3+) based organic halide perovskite has drawn attention as a substitution for lead-free perovskites, since it is a non-toxic 6p-block element, isoelectronic with Pb2+. Methylammonium bismuth iodide ((CH3NH3)3Bi2I9) is reported for its non-toxic constituents ...


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