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Full-Text Articles in Mechanical Engineering

Surface Treatments To Tailor The Wettability Of Carbon Nanotube Arrays, Lvmeng He Jan 2015

Surface Treatments To Tailor The Wettability Of Carbon Nanotube Arrays, Lvmeng He

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Carbon nanotubes (CNTs) have gained great attention due to their excellent mechanical, electrical, and thermal properties. Carbon nanotube (CNT) arrays attached to solid substrates resemble a nano-carpet and have potentials in a variety of devices. In this study, the focus is to investigate the surface modification approaches of CNT carpets on flat (compressed) graphite. Wettability, or permeation of a liquid such as water into the CNT strands, may play very significant roles in many applications where a CNT-coated device may be used in aqueous environment. Short-term microwave plasma treatments were used in this project to functionalize CNT carpets for wettability. …


An Experimental Investigation On Friction And Scuffing Failure Of Lubricated Point Contacts, Sai Goutham Soma Jan 2015

An Experimental Investigation On Friction And Scuffing Failure Of Lubricated Point Contacts, Sai Goutham Soma

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Scuffing failure is a catastrophic thermal failure mode induced by the extreme surface temperature of the contacting components. As two mechanical elements roll against each other with high sliding motion, the frictional heat flux elevates the surface temperature to exceed the critical limit, resulting in the welding of the surfaces. The relative motion then tears the welded surfaces apart, causing the damage. Scuffing failure has been an important failure mode for rolling machine elements such as bearings and gears in aerospace applications, owing to the very high operating speeds. Recently, this failure mode has extended to the automotive field, where …


High Temperature Transient Creep Analysis Of Metals, Sara Mirmasoudi Jan 2015

High Temperature Transient Creep Analysis Of Metals, Sara Mirmasoudi

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The ability to design vehicles capable of reaching hypersonic speeds has become a necessity to satisfy industry requirements, hence requiring the need for better understanding of creep behavior of materials. Although the steady state creep of metals has been analyzed rigorously, there is little known about transient creep of many metals. Understanding transient creep behavior of metals is crucial in analysis and design of short term hypersonic flight applications. Hence, a transient creep analysis of 304SS, Al7075-T6, Al2024-T6, Inconel 625, Inconel 718, and Rene N4 is carried out focusing on the microstructural behavior of these metals undergoing high temperature operating …


A Distributed Surrogate Methodology For Inverse Most Probable Point Searches In Reliability Based Design Optimization, James Davidson Jan 2015

A Distributed Surrogate Methodology For Inverse Most Probable Point Searches In Reliability Based Design Optimization, James Davidson

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Surrogate models are commonly used in place of prohibitively expensive computational models to drive iterative procedures necessary for engineering design and analysis such as global optimization. Additionally, surrogate modeling has been applied to reliability based design optimization which constrains designs to those which provide a satisfactory reliability against failure considering system parameter uncertainties. Through surrogate modeling the analysis time is significantly reduced when the total number of evaluated samples upon which the final model is built is less than the number which would have otherwise been required using the expensive model directly with the analysis algorithm. Too few samples will …