Browsing by Subject "high temperature"
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Item Advanced Induction Motor End Ring Design Features for High Speed Applications(IEEE, 2005-05) Caprio, M.T.; Lelos, V.; Herbst, J.D.; Upshaw, J.L.This paper presents advancements in induction motor endring design to overcome mechanical limitations and extend the operating speed range and joint reliability of induction machines. A novel endring design met the challenging mechanical requirements of this high speed, high temperature, power dense application, without compromising electrical performance. Analysis is presented of the advanced endring design features including a non uniform cross section, hoop stress relief cuts, and an integrated joint boss, which reduced critical stress concentrations, allowing operation under a broad speed and temperature design range. A generalized treatment of this design approach is presented comparing the concept results to conventional design techniques. Additionally, a low temperature joining process of the bar/end ring connection is discussed that provides the required joint strength without compromising the mechanical strength of the age hardened parent metals. A description of a prototype 2 MW, 15,000 rpm flywheel motor generator embodying this technology is presentedItem Characterization of a 50kW Inductively Coupled Plasma Torch for Testing of Ablative Thermal Protection Materials Using Non-Air Gases(2018-05) Cha, Han All; Clemens, NoelThermal protection systems have been a major area of study since the advent of space flight, but recent efforts towards crewed spaceflight missions have placed a new importance on the development of such systems. The 50 kW Inductively Coupled Plasma (ICP) Torch Facility at The University of Texas at Austin allows for rapid testing of high-temperature aerospace materials essential to the development of thermal protection systems in planetary re-entry applications. This ICP Torch Facility has been previously characterized using air as the test gas. However, planets of interest for future exploration have atmospheric compositions that differ from air, so testing heat shield materials in the presence of other gases is critical. To address this disparity between tested and actual environment, the current work characterizes the torch using various combinations of argon, CO2, and N2 by determining its operational range at various power settings, mass flow rates, and mixtures these gases. At each setting, the cold-wall heat flux is also measured to determine the range the torch is able to provide. Measurements indicate that using pure Ar gives the torch the largest operating range with regard to power setting and gas injection mass flow rate, and mixing argon into other gases drastically increases the stable operating range compared to the pure gas. Pure CO2 does not form a stable plasma discharge, but a mixture of 50% argon and 50% CO2 (by mass) provides stable operation up to 40 slpm total gas flow rate with a maximum heat flux of 98 W/cm2. Smaller percentages of CO2 allow the cold-wall heat flux to be increased to 110 W/cm2. Pure N2 forms a stable plasma discharge, but the operating range is very limited, providing stable operation up to 20 slpm total gas flow rate with a maximum heat flux of 110 W/cm2.Item Development of Novel High Temperature Laser Powder Bed Fusion System for the Processing of Crack-Susceptible Alloys(University of Texas at Austin, 2018) Caprio, L.; Chiari, G.; Demir, A.G.; Previtali, B.In the industrial panorama, Laser Powder Bed Fusion (LPBF) systems enable for the near net shaping of metal powders into complex geometries with unique design features. This makes the technology appealing for many industrial applications, which require high performance materials combined with lightweight design or conformal cooling channels. However, many of the alloys that would be ideal for the realisation of these functional components are classified as difficultly weldable due to their cracking sensitivity. Currently, industrial SLM systems employ baseplate preheating to minimise these effects although this solution is limitedly effective along the build direction and often does not achieve high enough temperatures for the realisation of crack-free specimen. In this work, the design and implementation of a novel inductive high temperature LPBF system is presented. Furthermore, preliminary results regarding depositions of Titanium Aluminide alloy with and without preheating are reported, showing the potential of the solution developed.Item Elevated Temperature Mechanical and Microstructural Characterization of SLM SS304L(University of Texas at Austin, 2019) Hecht, G.R.; Isanaka, S.P.; Newkirk, J.W.SLM built SS304L was annealed and water quenched to minimize residual stress and avoid carbide precipitation. Mini-tensile characterization of strength and elongation at temperature conditions up to 800˚ C, along with observations of the associated microstructural transformations were utilized to understand the changes produced in SLM SS304L. As-built and annealed specimens were found to exhibit decreasing strength and elongation with increasing temperature as expected. Carbide precipitates appeared after short times at high temperatures within both as-built and annealed specimens for all cases, but no brittle intermetallic phase development was observed for any of the temperatures investigated. While the lack of Sigma, Chi or Laves phases were anticipated, the premature formation of carbides is unexpected behavior for this composition of SS 304L. It is an indication of higher sensitivity of SLM made material. An additional change in the etch response was also observed between as-built and annealed specimens. It is theorized that annealing caused all ferritic and other residual phases present in as-built SLM SS 304L to fully transform into austenite. The cellular structure observed in the as-built specimen was also dissolved due to annealing and water quenching possibly leading to the strength loss observed.