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Full-Text Articles in Mechanical Engineering
Thermal Shock Fracture Behaviors Of Functionally Graded Ceramics, Wenjin Luo
Thermal Shock Fracture Behaviors Of Functionally Graded Ceramics, Wenjin Luo
Electronic Theses and Dissertations
This thesis uses a thermal fracture mechanics model to study the thermal shock fracture behavior of functionally graded ceramics (FGC). The specimen used in this study is a FGC strip with an edge crack on one surface. A severe thermal shock is applied on the cracked surface. The temperature field in a thermally shocked FGC strip is evaluated first using a closed form solution. Thermal stresses, thermal stress intensity factors (TSIF) and critical thermal shocks are evaluated using a thermomechanics and fracture mechanics approach. The effective thermal properties of the FGC specimens are estimated using micromechanics models for conventional composites. …
Photocatalytic Oxidation Of Carbon Monoxide Using Sputter Deposited Molybdenum Oxide Thin Films On A Silicon Dioxide Substrate, Donald Bragg
Photocatalytic Oxidation Of Carbon Monoxide Using Sputter Deposited Molybdenum Oxide Thin Films On A Silicon Dioxide Substrate, Donald Bragg
Electronic Theses and Dissertations
CO contamination is common in hydrogen extraction processes. Proton exchange membrane fuel cells need a source of hydrogen containing less than 10ppm of CO to avoid the irreversible poisoning of the fuel cell’s platinum anode. Platinum metal is commonly used as a catalyst for the purification of hydrogen gas. An effort has been put forth to replace the expensive platinum catalyst with a less expensive alternative. Photocatalytically active metal oxide semiconductors have shown promise as less expensive alternatives to platinum for redox reactions such as the oxidation of CO. This research studies a MoO3 sputter deposited thin film on a …
High Temperature Compression Testing Of Monolithic Silicon Carbide (Sic), Adam L. Mcnaughton
High Temperature Compression Testing Of Monolithic Silicon Carbide (Sic), Adam L. Mcnaughton
Electronic Theses and Dissertations
High temperature compression tests were administered in an oxidizing atmosphere on a commercially available monolithic (un-reinforced) reaction bonded silicon carbide (RBSiC) and an in-house processed silicon carbide based on a pre-ceramic polymer precursor. Ceramics such as silicon carbide have exceptional mechanical properties for both structural and thermal load applications. High tolerance specimen preparation via diamond wheel cutting and grinding to allow for compression testing on both types of silicon carbide ceramic at temperatures ranging from 20°C (68°F) to 1000°C (1832°F) is also addressed. Two types of specimen geometry were chosen due to the high strength and high stiffness of silicon …
Developing Dns Tools To Study Channel Flow Over Realistic Plaque Morphology, Ryan M. Beaumont
Developing Dns Tools To Study Channel Flow Over Realistic Plaque Morphology, Ryan M. Beaumont
Electronic Theses and Dissertations
In a normal coronary artery, the flow is laminar and the velocity is parabolic in nature. Over time, plaques deposit along the artery wall, narrowing the artery and creating an obstruction, a stenosis. As the stenosis grows, the characteristics of the flow change and transition occurs, resulting in turbulent flow distal to the stenosis. To date, direct numerical simulation (DNS) of turbulent flow has been performed in a number of studies to understand how stenosis modifies flow dynamics. However, the effect of the actual shape and size of the obstruction has been disregarded in these DNS studies. An ideal approach …