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Thermography Detection On The Fatigue Damage, Bing Yang
Thermography Detection On The Fatigue Damage, Bing Yang
Doctoral Dissertations
It has always been a great temptation in finding new methods to in-situ “watch” the material fatigue-damage processes so that in-time reparations will be possible, and failures or losses can be minimized to the maximum extent. Realizing that temperature patterns may serve as fingerprints for stress-strain behaviors of materials, a state-of-art infrared (IR) thermography camera has been used to “watch” the temperature evolutions of both crystalline and amorphous materials “cycle by cycle” during fatigue experiments in the current research.
The two-dimensional (2D) thermography technique records the surface-temperature evolutions of materials. Since all plastic deformations are related to heat dissipations, thermography …
Effects Of Environment And Frequency On The Fatigue Behavior Of The Spallation Neutron Source (Sns) Target Container Material - 316 Ln Stainless Steel, Hongbo Tian
Doctoral Dissertations
As the candidate target container material of the new Spallation Neutron Source (SNS) being designed and constructed at the Oak Ridge National Laboratory (ORNL), 316 low-carbon nitrogen-added (LN) stainless steel (SS) will operate in an aggressive environment, subjected to intense fluxes of high-energy protons and neutrons while exposed to liquid mercury. The SNS is an accelerator-based neutron source that provides pulsed beams of spallation neutrons by bombarding a mercury target with 1 GeV protons. The function of the SNS is to convert a short pulse (< 1 ms, 60 Hz, 17 kJ/pulse), high-average-power (1 MW), 1-GeV proton beam into 18 lower-energy (< 1eV), short-pulsed (~ tens of ms) neutron beams optimized for use by neutron-scattering instruments.
The current project is oriented toward materials studies regarding the effects of test environment …
Integrated Field Emission Electron Guns With Single Vertically Aligned Carbon Nanofiber Cathodes, Michael Alberto Guillorn
Integrated Field Emission Electron Guns With Single Vertically Aligned Carbon Nanofiber Cathodes, Michael Alberto Guillorn
Doctoral Dissertations
Nanostructured carbon-based materials hold great promise as field emission (FE) cathodes for integrated FE devices. These materials display remarkable FE properties as a consequence of their unique chemical and physical properties. Among this class of materials, the vertically aligned carbon nanofiber (VACNF) is exceptional in that its synthesis can be deterministically controlled. This has enabled the characterization of the FE properties of individual VACNF grown on Si substrates. The results of these studies indicate that the VACNF is an excellent candidate for integrated FE electron sources where the generation of a focused electron beam from a microscale structure is required. …
Rheology Of Lyocell Solutions From Different Cellulosic Sources And Development Of Regenerated Cellulosic Microfibers, Zuopan Li
Doctoral Dissertations
The primary goals of the study were to develop manufactured cellulosic fibers and microfibers from wood pulps as well as from lignocellulosic agricultural by-products and to investigate alternative cellulosic sources as raw materials for lyocell solutions. A protocol was developed for the lyocell preparation from different cellulose sources. The cellulose sources included commercial dissolving pulps, commercial bleached hardwood, unbleached hardwood, bleached softwood, unbleached softwood, bleached thermomechanical pulp, unbleached thermomechanical pulp, bleached recycled newsprint, unbleached recycled newsprint, bagasse and kudzu.
The rheological behavior of solutions was characterized. Complex viscosities and effective elongational viscosities were measured and the influences of parameters such …