Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 7 of 7
Full-Text Articles in Mechanical Engineering
Computer Simulation Of Pore Migration Due To Temperature Gradients In Nuclear Oxide Fuel, Ian Wayne Vance
Computer Simulation Of Pore Migration Due To Temperature Gradients In Nuclear Oxide Fuel, Ian Wayne Vance
Graduate Theses and Dissertations
A phase-field simulation model is being presented that captures the thermal-gradient-driven migration of pores in oxide fuel associated with fuel restructuring. The model utilizes a Cahn-Hilliard equation supplemented with an advection term to describe the vapor transport of fuel material through the pore interior due to gradients in vapor pressure. In addition, the model also captures changes in a migrating pores’ morphology. Simulations demonstrate that the model successfully predicts pore migration towards the hottest portion of the fuel, the centerline. The simulations also demonstrate changes in pore shape that are in agreement with previous experimental observations. Initially isotropic pores are …
Characterization Of Plastic Deformation Evolution In Single Crystal And Nanocrystalline Cu During Shock By Atomistic Simulations, Mehrdad Mirzaei Sichani
Characterization Of Plastic Deformation Evolution In Single Crystal And Nanocrystalline Cu During Shock By Atomistic Simulations, Mehrdad Mirzaei Sichani
Graduate Theses and Dissertations
The objective of this dissertation is to characterize the evolution of plastic deformation mechanisms in single crystal and nanocrystalline Cu models during shock by atomistic simulations. Molecular dynamics (MD) simulations are performed for a range of particle velocities from 0.5 to 1.7 km/s and initial temperatures of 5, 300 and 600 K for single crystal models as well as particle velocities from 1.5 to 3.4 km/s for nanocrystalline models with grain diameters of 6, 11, 16 and 26 nm. For single crystal models, four different shock directions are selected, <100>, <110>, <111> and <321>, and dislocation density behind the shock wave …
The Effect Of Process Parameters And Surface Condition On Bond Strength Between Additively Manufactured Components And Polymer Substrates, Bharat Bhushan Chivukula
The Effect Of Process Parameters And Surface Condition On Bond Strength Between Additively Manufactured Components And Polymer Substrates, Bharat Bhushan Chivukula
Graduate Theses and Dissertations
Additive patching is a process in which printers with multiple axes deposit molten material onto a pre-defined surface to form a bond. Studying the effect of surface roughness and process parameters selected for printing auxiliary part on the bond helps in improving the strength of the final component. Particularly, the influence of surface roughness, as established by adhesion theory, has not been evaluated in the framework of additive manufacturing (AM). A full factorial design of experiments with five replications was conducted on two levels and three factors, viz., layer thickness, surface roughness, and raster angle to examine the underlying effects …
Crack Growth Behavior Under Creep-Fatigue Conditions Using Compact And Double Edge Notch Tension-Compression Specimens, Santosh B. Narasimha Chary
Crack Growth Behavior Under Creep-Fatigue Conditions Using Compact And Double Edge Notch Tension-Compression Specimens, Santosh B. Narasimha Chary
Graduate Theses and Dissertations
The American Society for Testing and Materials (ASTM) has recently developed a new standard for creep-fatigue crack growth testing, E 2760-10, that supports testing compact specimens, C(T), under load controlled conditions. C(T) specimens are commonly used for fatigue and creep-fatigue crack growth testing under constant-load-amplitude conditions. The use of these specimens is limited to positive load ratios. They are also limited in the amount of crack growth data that can be developed at high stress intensity values due to accumulation of plastic and/or creep strains leading to ratcheting in the specimen. Testing under displacement control can potentially address these shortcomings …
Silica Nanoparticle-Based Coatings With Superhydrophilic And Superhydrophobic Properties, Robert Andrew Fleming
Silica Nanoparticle-Based Coatings With Superhydrophilic And Superhydrophobic Properties, Robert Andrew Fleming
Graduate Theses and Dissertations
Superhydrophilic and superhydrophobic surfaces have potential for implementation into a variety of fields, including self-cleaning surfaces, anti-fogging transparent materials, and biomedical applications. In this study, sandblasting, oxygen plasma treatments, silica nanoparticle films, and a low surface energy fluorocarbon film were employed to change the natural surface wettability of titanium, glass, and polyethylene terephthalate (PET) substrates, with an aim to produce superhydrophilic and superhydrophobic behavior. The effects of these surface modifications are characterized by water contact angles (WCAs), surface wetting stability, surface morphology and roughness, surface elemental composition, and optical transmittance measurements. The results show that stable superhydrophilic and superhydrophobic surfaces …
Design, Fabrication, Testing Of Cnt Based Isfet And Characterization Of Nano/Bio Materials Using Afm, Zhuxin Dong
Design, Fabrication, Testing Of Cnt Based Isfet And Characterization Of Nano/Bio Materials Using Afm, Zhuxin Dong
Graduate Theses and Dissertations
A combination of Carbon Nanotubes (CNTs) and Ion Selective Field Effect Transistor (ISFET) is designed and experimentally verified in order to develop the next generation ion concentration sensing system. Micro Electro-Mechanical System (MEMS) fabrication techniques, such as photolithography, diffusion, evaporation, lift-off, packaging, etc., are required in the fabrication of the CNT-ISFET structure on p-type silicon wafers. In addition, Atomic Force Microscopy (AFM) based surface nanomachining is investigated and used for creating nanochannels on silicon surfaces. Since AFM based nanomanipulation and nanomachining is highly controllable, nanochannels are precisely scratched in the area between the source and drain of the FET where …
Surface Wetting And Friction Studies Of Nano-Engineered Surfaces On Copper Substrate, Julius Sheldon Morehead
Surface Wetting And Friction Studies Of Nano-Engineered Surfaces On Copper Substrate, Julius Sheldon Morehead
Graduate Theses and Dissertations
Nano-engineered-textures on a material surface can dramatically improve the wetting and non-wetting properties of a surface, and they also show promise to address friction issues that affect surfaces in contact. In this work, aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) was used to produce nano-textures on copper (Cu) substrates. A study was performed to examine the effects of changing the annealing conditions and a-Si thickness on nano-texture formation. The creation of various nano-topographies and chemically modifying them using octafluorocyclobutane (C4F8) was performed to control hydrophilicity, hydrophobicity, and oil affinity of nano-textured surfaces. A video-based contact angle measurement system was used …