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Thermodynamic Evaluation And Modeling Of Grade 91 Alloy And Its Secondary Phases Through Calphad Approach, Andrew Logan Smith Mr. 2018 Florida International University

Thermodynamic Evaluation And Modeling Of Grade 91 Alloy And Its Secondary Phases Through Calphad Approach, Andrew Logan Smith Mr.

FIU Electronic Theses and Dissertations

Grade 91 (Gr.91) is a common structural material used in boiler applications and is favored due to its high temperature creep strength and oxidation resistance. Under cyclic stresses, the material will experience creep deformation eventually causing the propagation of type IV cracks within its heat-affected-zone (HAZ) which can be a major problem under short-term and long-term applications. In this study, we aim to improve this premature failure by performing a computational thermodynamic study through the Calculation of Phase Diagram (CALPHAD) approach. Under this approach, we have provided a baseline study as well as simulations based on additional alloying elements ...


Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials, Xingeng Yang 2018 University of Arkansas, Fayetteville

Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials, Xingeng Yang

Theses and Dissertations

In this research, nanomaterial-based packaging materials for photovoltaic (PV) panels are investigated. A hydrophobic/anti-reflective surface coating which not only repels water from the top glass of a PV panel but at the same time reduces its light reflectance is investigated. COMSOL simulation results indicate that taller ellipsoid rod (aspect ratio = 5) reflects less light than shorter rod (aspect ratio = 0.5) in the desired spectrum for solar energy harvest from 400nm-700nm. The addition of a polymer layer on these ellipsoid rods broadens the light incident angle from 23° to 34°, from which light can be efficiently absorbed. Based on ...


Hawai'i Wildlife Fund V. County Of Maui, Lowell J. Chandler 2018 Alexander Blewett III School of Law at the University of Montana

Hawai'i Wildlife Fund V. County Of Maui, Lowell J. Chandler

Public Land & Resources Law Review

In Hawai’i Wildlife Fund v. County of Maui, the Ninth Circuit held that the plain language of the Clean Water Act provides jurisdiction over indirect discharges of pollutants from a point source into groundwater that is shown to be connected to navigable waters. The court found that studies confirmed pollutants entering the Pacific Ocean were fairly traceable to the County of Maui’s sewage disposal wells. In affirming the district court’s ruling, the Ninth Circuit held that Maui County violated the Clean Water Act by discharging pollutants into a navigable water without the required permit. The court also ...


A True Self-Supportive Structure, Connor Kaldor 2018 Kent State University

A True Self-Supportive Structure, Connor Kaldor

Undergraduate Research Symposium

Self-supportive concrete shells are a harmonious mix of utilitarian materiality and inspiring form. Structurally stable, beautiful, and easy to conceptualize; Most shells structures can be derived from simplistic exercises and accurately represented by scaled models. These structures are something truly special but despite the great achievements of lightweight shell structures, they still require one unfortunate necessity. A shell structure often requires intensive form work or scaffolding to facilitate the construction process. Some solutions exist like cable-stayed key stones or streamlined versions of what we know as scaffolding. While nominally effective, these solutions fall short of the achievements of what they ...


Manufacturing Process Simulation – On Its Way To Industrial Application, Dennis Otten, Tobias A. Weber, Jan-Christoph Arent 2018 University of Applied Sciences Augsburg

Manufacturing Process Simulation – On Its Way To Industrial Application, Dennis Otten, Tobias A. Weber, Jan-Christoph Arent

International Journal of Aviation, Aeronautics, and Aerospace

Manufacturing process simulation (MPS) has become more and more important for aviation and the automobile industry. A highly competitive market requires the use of high performance metals and composite materials in combination with reduced manufacturing cost and time as well as a minimization of the time to market for a new product. However, the use of such materials is expensive and requires sophisticated manufacturing processes. An experience based process and tooling design followed by a lengthy trial-and-error optimization is just not contemporary anymore. Instead, a tooling design process aided by simulation is used more often. This paper provides an overview ...


Performance Evaluation Of A Semi-Active Cladding Connection For Multi-Hazard Mitigation, Yongqiang Gong, Liang Cao, Laura Micheli, Simon Laflamme 2018 Iowa State University

Performance Evaluation Of A Semi-Active Cladding Connection For Multi-Hazard Mitigation, Yongqiang Gong, Liang Cao, Laura Micheli, Simon Laflamme

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

A novel semi-active damping device termed Variable Friction Cladding Connection (VFCC) has been previously proposed to leverage cladding systems for the mitigation of natural and man-made hazards. The VFCC is a semi-active friction damper that connects cladding elements to the structural system. The friction force is generated by sliding plates and varied using an actuator through a system of adjustable toggles. The dynamics of the device has been previously characterized in a laboratory environment. In this paper, the performance of the VFCC at mitigating non-simultaneous multi-hazard excitations that includes wind and seismic loads is investigated on a simulated benchmark building ...


Residual Tensile Strength And Bond Properties Of Gfrp Bars After Exposure To Elevated Temperatures, Devon S. Ellis, Habib Tabatabai, Azam Nabizadeh 2018 Ellis Engineering

Residual Tensile Strength And Bond Properties Of Gfrp Bars After Exposure To Elevated Temperatures, Devon S. Ellis, Habib Tabatabai, Azam Nabizadeh

Civil and Environmental Engineering Faculty Articles

The use of fiber reinforced polymer (FRP) bars in reinforced concrete members enhances corrosion resistance when compared to traditional steel reinforcing bars. Although there is ample research available on the behavior of FRP bars and concrete members reinforced with FRP bars under elevated temperatures (due to fire), there is little published information available on their post-fire residual load capacity. This paper reports residual tensile strength, modulus of elasticity, and bond strength (to concrete) of glass fiber reinforced polymer (GFRP) bars after exposure to elevated temperatures of up to 400 C and subsequent cooling to an ambient temperature. The results showed ...


Magnetic Two-Way Valves For Paper-Based Capillary-Driven Microfluidic Devices, Mario Fratzl, Boyce Chang, Stephanie Oyola-Reynoso, Guillaume Blaire, Sarah Delshad, Thibaut Devillers, Thomas Ward, III, Nora M. Dempsey, Jean-Francis Bloch, Martin M. Thuo 2018 Université Grenoble Alpes

Magnetic Two-Way Valves For Paper-Based Capillary-Driven Microfluidic Devices, Mario Fratzl, Boyce Chang, Stephanie Oyola-Reynoso, Guillaume Blaire, Sarah Delshad, Thibaut Devillers, Thomas Ward, Iii, Nora M. Dempsey, Jean-Francis Bloch, Martin M. Thuo

Materials Science and Engineering Publications

This article presents a magnetically actuated two-way, three-position (+, 0, −), paper-based microfluidic valve that includes a neutral position (0)--the first of its kind. The system is highly robust, customizable, and fully automated. The advent of a neutral position and the ability to precisely control switching frequencies establish a new platform for highly controlled fluid flows in paper-based wicking microfluidic devices. The potential utility of these valves is demonstrated in automated, programmed, patterning of dyed liquids in a wicking device akin to a colorimetric assay but with a programmed fluid/reagent delivery. These valves are fabricated using facile methods and thus ...


Magnetostructural Phase Transitions And Magnetocaloric Effect In (Gd5-Xscx)Si1.8ge2.2, Kirk Rudolph, Arjun Pathak, Yaroslav Mudryk, Vitalij K. Pecharsky 2018 Iowa State University and Ames Laboratory

Magnetostructural Phase Transitions And Magnetocaloric Effect In (Gd5-Xscx)Si1.8ge2.2, Kirk Rudolph, Arjun Pathak, Yaroslav Mudryk, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

Future advancements in magnetocaloric refrigeration/heat pumping technologies depend on the discovery of new materials that demonstrate large, tunable magnetocaloric effects (MCEs) in the vicinity of coupled magnetic and structural phase transitions that occur reversibly with minimum hysteresis. With this in mind, we investigate phase transitions, microstructure, magnetic, thermal, magnetocaloric, and transport properties of (Gd5-xScx)Si1.8Ge2.2 compounds. Replacement of magnetic Gd with non-magnetic Sc in Gd5-xScxSi1.8Ge2.2 increases the ferromagnetic to paramagnetic first order phase transition temperature, TC, with only a minor reduction in MCE when x ≤ 0.2. We also demonstrate that hydrostatic pressure further increases ...


Propeller Design Requirements For Quadcopters Utilizing Variable Pitch Propellers, Ian R. McAndrew, Elena Navarro, Ken Witcher 2018 Embry-Riddle Aeronautical University

Propeller Design Requirements For Quadcopters Utilizing Variable Pitch Propellers, Ian R. Mcandrew, Elena Navarro, Ken Witcher

Publications

Unmanned aerial vehicles, UAV, has increases in the drastically in these past several years since their costs reduced. This research is based and built upon previous research presented in a conference. With the advent of commercial Quadcopters, four propeller systems, are used, being designed and used to operate the advantages of both flight and hovering. The basic design of their propeller blades has not evolved from the early days of manned flight when wooden fixed blades were used. In this paper that expands upon previous findings and discussions it explores the historical developments. Furthermore, how the expansion and reduction in ...


Effects Of Microstructure And Crystallography On Mechanical Properties Of Cold-Rolled Sae1078 Pearlitic Steel, Y. Liu, C. D. Yang, M. Liu, C. H. Wang, Y. C. Dai, X. Li, Alan M. Russell, C. X. Zhang, Z. H. Zhang, G. H. Cao 2018 Shanghai University

Effects Of Microstructure And Crystallography On Mechanical Properties Of Cold-Rolled Sae1078 Pearlitic Steel, Y. Liu, C. D. Yang, M. Liu, C. H. Wang, Y. C. Dai, X. Li, Alan M. Russell, C. X. Zhang, Z. H. Zhang, G. H. Cao

Materials Science and Engineering Publications

The evolution of the microstructure and crystallography in SAE1078 pearlitic steel sheets under different cold-rolling reductions of up to 90% were quantified using transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). The mechanical properties were determined by tensile testing at room temperature. TEM analysis showed that the pearlite structure was obviously refined with the interlamellar spacing decreasing to about 57 nm at the rolling reduction of 90%. EBSD investigations indicated that the ferrite exhibited a {001}texture in the 90% cold-rolled pearlitic steel. The dislocations were mainly concentrated during cold rolling between the 10% and 70 ...


A Microstructure-Based Model Validated Experimentally For Quantification Of Short Fatigue Crack Growth In Three-Dimensions, Pei Cai 2018 University of Kentucky

A Microstructure-Based Model Validated Experimentally For Quantification Of Short Fatigue Crack Growth In Three-Dimensions, Pei Cai

Theses and Dissertations--Chemical and Materials Engineering

Built on the recent successes in understanding the crystallographic mechanism for short fatigue crack (SFC) growth across a grain boundary (GB) and developing an experimental method to quantify the GB resistance against short crack growth, a microstructure-based model was developed in this study to simulate the growth behaviors of SFCs in 3-D, by taking into account both the driving force and resistance along at each point along the crack front in an alloy. It was found that the GB resistance was a Weibull function of the minimum twist angle of crack deflection at the boundary in AA2024-T3 Al alloys. In ...


Assisted Development Of Mesophase Pitch With Dispersed Graphene And Its Resulting Carbon Fibers, Aaron Owen 2018 University of Kentucky

Assisted Development Of Mesophase Pitch With Dispersed Graphene And Its Resulting Carbon Fibers, Aaron Owen

Theses and Dissertations--Mechanical Engineering

The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and ...


Detection Of Buried Non-Metallic (Plastic And Frp Composite) Pipes Using Gpr And Irt, Jonas Kavi 2018 West Virginia University

Detection Of Buried Non-Metallic (Plastic And Frp Composite) Pipes Using Gpr And Irt, Jonas Kavi

Graduate Theses, Dissertations, and Problem Reports

This research investigated alternative strategies for making buried non-metallic pipes (CFRP, GFRP, and PVC) easily locatable using Ground Penetrating Radar (GPR). Pipe diameters up to 12" and buried with up to 4 ft. of soil cover were investigated. The findings of this study will help address the detection problem of non-metallic pipelines and speed the adoption of composite pipes by the petroleum and natural gas industry. The research also investigated the possibility of locating buried pipes transporting hot fluids using Infrared Thermography (IRT).

Results from the study have shown that, using carbon fabric and aluminum tape overlay on non‑metallic ...


Nondestructive Evaluation Of Salvage White Spruce, Tyler Hovde 2018 Michigan Technological University

Nondestructive Evaluation Of Salvage White Spruce, Tyler Hovde

Dissertations, Master's Theses and Master's Reports

Knowledge of wood quality in dead standing trees is an important topic with recent increases in defoliation across North America. Obtaining wood quality information for defoliated trees would help stakeholders in the timber products industry sort and sell salvaged material for the highest possible value. This research investigates the ability to measure wood quality of white spruce (Picea glauca) after spruce budworm (Choristoneura fumiferana) attack using acoustic nondestructive evaluation. We compared stress wave velocities measured on standing trees to trees’ visual appearance. After harvest and processing of selected trees into bolts, standing-tree stress wave velocities were compared to bolt acoustic ...


Liquid Interaction With Non-Wettable Surfaces Structured With Macroscopic Ridges, Mehran Abolghasemibizaki 2018 Virginia Commonwealth University

Liquid Interaction With Non-Wettable Surfaces Structured With Macroscopic Ridges, Mehran Abolghasemibizaki

Theses and Dissertations

Self-cleaning, anti-corrosion, anti-icing, dropwise-condensation, and drag-reduction are some applications in which superhydrophobic surfaces are implemented. To date, all the studies associated with superhydrophobic surfaces have been dedicated to understanding the liquid interaction with surfaces that are macroscopically smooth. The current study investigates the solid-liquid interaction of such surfaces which are fully decorated with macroscopic ridges (ribbed surfaces). In particular, the drop motion and impact on our newly designed non-wettable ribbed surface have been investigated in this work. Our experimental investigations have shown that liquid drops move faster on the ribbed surfaces due to lower friction induced by such a surface ...


Development And Verification Of A Confined Discretized Solid Flame Model For Calculating Heat Flux On Concrete Tunnel Liners, Kyle James Root 2018 Lehigh University

Development And Verification Of A Confined Discretized Solid Flame Model For Calculating Heat Flux On Concrete Tunnel Liners, Kyle James Root

Theses and Dissertations

Road tunnels are susceptible to severe fire-induced heat flux due to the constant presence of vehicular traffic combined with the likelihood of accidents and subsequent combustion. Rapid assessment of thermal demands is a necessity to calculate appropriate design limit states and to better understand risk potential in a multitude of underground environments. A proposed approach is developed which allows for rapid assessment of thermal demands using models that are validated and informed through computationally intensive numerical assessment, experimental data, and semi-empirical relationships based on first principles. Utilizing Rhino and Grasshopper, the discretized solid flame model is adapted to account for ...


Evaluation Of The Effect Of Tack Coat Type, Application Rate, And Surface Type On Interlayer Shear Strength, Chamika Prashan Dharmarathna 2018 South Dakota State University

Evaluation Of The Effect Of Tack Coat Type, Application Rate, And Surface Type On Interlayer Shear Strength, Chamika Prashan Dharmarathna

Electronic Theses and Dissertations

Tack coat is an asphaltic material applied between asphalt pavement layers. Since pavement is a multilayered structure, it is highly important to make proper bond between the layers to achieve a monolithic behavior. Hence, inadequate bond due to application of inadequate amount of tack coat may lead to poor structural behavior and premature failure. Also, applying excessive amount of tack coat may lead to layer slippage and binder migration. Therefore, it is highly important to apply an optimum amount of tack coat between layers. Over the past decades several studies have been conducted to determine the optimum tack coat application ...


The Formation Mechanism Of Α-Phase Dispersoids And Quantification Of Fatigue Crack Initiation By Experiments And Theoretical Modeling In Modified Aa6061 (Al-Mg-Si-Cu) Alloys, Gongwang Zhang 2018 University of Kentucky

The Formation Mechanism Of Α-Phase Dispersoids And Quantification Of Fatigue Crack Initiation By Experiments And Theoretical Modeling In Modified Aa6061 (Al-Mg-Si-Cu) Alloys, Gongwang Zhang

Theses and Dissertations--Chemical and Materials Engineering

AA6061 Al alloys modified with addition of Mn, Cr and Cu were homogenized at temperatures between 350 ºC and 550 ºC after casting. STEM experiments revealed that the formation of α-Al(MnFeCr)Si dispersoids during homogenization were strongly affected by various factors such as heating rate, concentration of Mn, low temperature pre-nucleation treatment and homogenization temperature. Through analysis of the STEM results using an image software Image-Pro, the size distributions and number densities of the dispersoids formed during different annealing treatments were quantitatively measured. It was revealed that increasing the heating rate or homogenization temperature led to a ...


High Pressure Phase Transformations Revisited, Valery I. Levitas 2018 Iowa State University

High Pressure Phase Transformations Revisited, Valery I. Levitas

Aerospace Engineering Publications

High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The ...


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