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ASU Electronic Theses and Dissertations


This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.


Date Range
2014 2018


The United States Department of Energy (DOE) has always held the safety and reliability of the nation's nuclear reactor fleet as a top priority. Continual improvements and advancements in nuclear fuels have been instrumental in maximizing energy generation from nuclear power plants and minimizing waste. One aspect of the DOE Fuel Cycle Research and Development Advanced Fuels Campaign is to improve the mechanical properties of uranium dioxide (UO2) for nuclear fuel applications. In an effort to improve the performance of UO2, by increasing the fracture toughness and ductility, small quantities of oxide materials have been added to samples to act …

Contributors
McDonald, Robert Edward, Peralta, Pedro, Rajagopalan, Jagannathan, et al.
Created Date
2014

The flow of liquid PDMS (10:1 v/v base to cross-linker ratio) in open, rectangular silicon micro channels, with and without a hexa-methyl-di-silazane (HMDS) or poly-tetra-fluoro-ethylene (PTFE) (120 nm) coat, was studied. Photolithographic patterning and etching of silicon wafers was used to create micro channels with a range of widths (5-50 μm) and depths (5-20 μm). The experimental PDMS flow rates were compared to an analytical model based on the work of Lucas and Washburn. The experimental flow rates closely matched the predicted flow rates for channels with an aspect ratio (width to depth), p, between one and two. Flow rates …

Contributors
Sowers, Timothy Wayne, Rajagopalan, Jagannathan, Herrmann, Marcus, et al.
Created Date
2014

The stability of nanocrystalline microstructural features allows structural materials to be synthesized and tested in ways that have heretofore been pursued only on a limited basis, especially under dynamic loading combined with temperature effects. Thus, a recently developed, stable nanocrystalline alloy is analyzed here for quasi-static (<100 s-1) and dynamic loading (103 to 104 s-1) under uniaxial compression and tension at multiple temperatures ranging from 298-1073 K. After mechanical tests, microstructures are analyzed and possible deformation mechanisms are proposed. Following this, strain and strain rate history effects on mechanical behavior are analyzed using a combination of quasi-static and dynamic strain …

Contributors
Turnage, Scott Andrew, Solanki, Kiran N, Rajagopalan, Jagannathan, et al.
Created Date
2017

This study uses Computational Fluid Dynamics (CFD) modeling to analyze the dependence of wind power potential and turbulence intensity on aerodynamic design of a special type of building with a nuzzle-like gap at its rooftop. Numerical simulations using ANSYS Fluent are carried out to quantify the above-mentioned dependency due to three major geometric parameters of the building: (i) the height of the building, (ii) the depth of the roof-top gap, and (iii) the width of the roof-top gap. The height of the building is varied from 8 m to 24 m. Likewise, the gap depth is varied from 3 m …

Contributors
Kailkhura, Gargi, Huang, Huei-Ping, Rajagopalan, Jagannathan, et al.
Created Date
2017

The study of response of various materials to intense dynamic loading events, such as shock loading due to high-velocity impacts, is extremely important in a wide variety of military and industrial applications. Shock loading triggers extreme states, leading to high pressures and strain rates, and neglecting strength is a typical approximation under such conditions. However, recent results have shown that strength effects are larger than expected, so they must be taken into account. Recently, hydrodynamic instabilities, the most common being the Rayleigh-Taylor (RTI) and Richtmyer-Meshkov (RMI) instabilities, have been used to infer the dynamic strength of materials at high pressure …

Contributors
Gopalakrishnan, Ashish, Peralta, Pedro, Rajagopalan, Jagannathan, et al.
Created Date
2017

The Very High Temperature Reactor (VHTR) is one of six conceptual designs proposed for Generation IV nuclear reactors. Alloy 617, a solid solution strengthened Ni-base superalloy, is currently the primary candidate material for the tubing of the Intermediate Heat Exchanger (IHX) in the VHTR design. Steady-state operation of the nuclear power plant at elevated temperatures leads to creep deformation, whereas loading transients including startup and shutdown generate fatigue. A detailed understanding of the creep-fatigue interaction in Alloy 617 is necessary before it can be considered as a material for nuclear construction in ASME Boiler and Pressure Vessel Code. Current design …

Contributors
Tahir, Fraaz, Liu, Yongming, Jiang, Hanqing, et al.
Created Date
2017

Uranium Dioxide (UO2) is a significant nuclear fission fuel, which is widely used in nuclear reactors. Understanding the influence of microstructure on thermo-mechanical behavior of UO2 is extremely important to predict its performance. In particular, evaluating mechanical properties, such as elasticity, plasticity and creep at sub-grain length scales is key to developing this understanding as well as building multi-scale models of fuel behavior with predicting capabilities. In this work, modeling techniques were developed to study effects of microstructure on Young’s modulus, which was selected as a key representative property that affects overall mechanical behavior, using experimental data obtained from micro-cantilever …

Contributors
Gong, Bowen, Peralta, Pedro, Rajagopalan, Jagannathan, et al.
Created Date
2015

Nanocrystalline (NC) and Ultrafine-grained (UFG) metal films exhibit a wide range of enhanced mechanical properties compared to their coarse-grained counterparts. These properties, such as very high strength, primarily arise from the change in the underlying deformation mechanisms. Experimental and simulation studies have shown that because of the small grain size, conventional dislocation plasticity is curtailed in these materials and grain boundary mediated mechanisms become more important. Although the deformation behavior and the underlying mechanisms in these materials have been investigated in depth, relatively little attention has been focused on the inhomogeneous nature of their microstructure (particularly originating from the texture …

Contributors
Izadi, Ehsan, Rajagopalan, Jagannathan, Peralta, Pedro, et al.
Created Date
2017

Interstitial impurity atoms can significantly alter the chemical and physical properties of the host material. Oxygen impurity in HCP titanium is known to have a considerable strengthening effect mainly through interactions with dislocations. To better understand such an effect, first the role of oxygen on various slip planes in titanium is examined using generalized stacking fault energies (GSFE) computed by the first principles calculations. It is shown that oxygen can significantly increase the energy barrier to dislocation motion on most of the studied slip planes. Then the Peierls-Nabbaro model is utilized in conjunction with the GSFE to estimate the Peierls …

Contributors
Gholami Bazehhour, Benyamin, Solanki, Kiran N, Liu, Yongming, et al.
Created Date
2018

The exceptional mechanical properties of polymers with heterogeneous structure, such as the high toughness of polyethylene and the excellent blast-protection capability of polyurea, are strongly related to their morphology and nanoscale structure. Different polymer microstructures, such as semicrystalline morphology and segregated nanophases, lead to coordinated molecular motions during deformation in order to preserve compatibility between the different material phases. To study molecular relaxation in polyethylene, a coarse-grained model of polyethylene was calibrated to match the local structural variable distributions sampled from supercooled atomistic melts. The coarse-grained model accurately reproduces structural properties, e.g., the local structure of both the amorphous and …

Contributors
Li, Yiyang, Oswald, Jay, Rajan, Subramaniam, et al.
Created Date
2017

Commercially pure (CP) and extra low interstitial (ELI) grade Ti-alloys present excellent corrosion resistance, lightweight, and formability making them attractive materials for expanded use in transportation and medical applications. However, the strength and toughness of CP titanium are affected by relatively small variations in their impurity/solute content (IC), e.g., O, Al, and V. This increase in strength is due to the fact that the solute either increases the critical stress required for the prismatic slip systems ({10-10}<1-210>) or activates another slip system ((0001)<11-20>, {10-11}<11-20>). In particular, solute additions such as O can effectively strengthen the alloy but with an attendant …

Contributors
Bhatia, Mehul Anoopkumar, Solanki, Kiran N, Peralta, Pedro, et al.
Created Date
2014

In engineering, buckling is mechanical instability of walls or columns under compression and usually is a problem that engineers try to prevent. In everyday life buckles (wrinkles) on different substrates are ubiquitous -- from human skin to a rotten apple they are a commonly observed phenomenon. It seems that buckles with macroscopic wavelengths are not technologically useful; over the past decade or so, however, thanks to the widespread availability of soft polymers and silicone materials micro-buckles with wavelengths in submicron to micron scale have received increasing attention because it is useful for generating well-ordered periodic microstructures spontaneously without conventional lithographic …

Contributors
Ma, Teng, Jiang, Hanqing, Yu, Hongyu, et al.
Created Date
2014