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  • Other Sources  (47)
  • MECHANICAL ENGINEERING  (27)
  • Spacecraft Design, Testing and Performance  (16)
  • Chemistry and Materials (General)
  • 2005-2009  (19)
  • 1990-1994  (21)
  • 1985-1989  (7)
  • 1
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    Cryogenic mechanisms for scanning and interchange of the Fabry-Perot interferometers in the ISO long wavelength spectrometer (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Infrared Space Observatory (ISO) is an ESA cornerstone mission for infrared astronomy. Schedules for launch in 1993, its four scientific instruments will provide unprecedented sensitivity and spectral resolution at wavelengths which are inaccessible using ground-based techniques. One of these, the Long Wavelength Spectrometer (LWS), will operate in the 45 to 180 micron region (Emery et. al., 1985) and features two Fabry-Perot interferometers mounted on an interchange mechanism. The entire payload module of the spacecraft, comprising the 60 cm telescope and the four focal plane instruments, is maintained at 2 to 4 K by an onboard supply of liquid helium. The mechanical design and testing of the cryogenic interferometer and interchange mechanisms are described.
    Keywords: MECHANICAL ENGINEERING
    Type: JPL, The 25th Aerospace Mechanisms Symposium; p 151-159
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  • 2
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    Robotic control and inspection verification (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Three areas of possible commercialization involving robots at the Kennedy Space Center (KSC) are discussed: a six degree-of-freedom target tracking system for remote umbilical operations; an intelligent torque sensing end effector for operating hand valves in hazardous locations; and an automatic radiator inspection device, a 13 by 65 foot robotic mechanism involving completely redundant motors, drives, and controls. Aspects concerning the first two innovations can be integrated to enable robots or teleoperators to perform tasks involving orientation and panal actuation operations that can be done with existing technology rather than waiting for telerobots to incorporate artificial intelligence (AI) to perform 'smart' autonomous operations. The third robot involves the application of complete control hardware redundancy to enable performance of work over and near expensive Space Shuttle hardware. The consumer marketplace may wish to explore commercialization of similiar component redundancy techniques for applications when a robot would not normally be used because of reliability concerns.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA, Washington, Technology 2000, Volume 2; p 298-307
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  • 3
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    Enhanced rotor modeling tailored for rub dynamic stability analysis and simulation (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: New methods are presented that allow straightforward application of complex nonlinearities to finite element based rotor dynamic analyses. The key features are: (1) the methods can be implemented with existing finite element or dynamic simulation programs, (2) formulation is general for simple application to a wide range of problems, and (3) implementation is simplified because nonlinear aspects are separated from the linear part of the model. The new techniques are illustrated with examples of inertial nonlinearity and torquewhirl which can be important in rubbing turbomachinery. The sample analyses provide new understanding of these nonlinearities which are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA, Lewis Research Center, Rotordynamic Instability Problems in High-Performance Turbomachinery, 1988; p 431-444
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  • 4
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    Incorporating general race and housing flexibility and deadband in rolling element bearing analysis (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Methods for including the effects of general race and housing compliance and outer race-to-housing deadband (clearance) in rolling element bearing mechanics analysis is presented. It is shown that these effects can cause significant changes in bearing stiffness characteristics, which are of major importance in rotordynamic response of turbomachinery and other rotating systems. Preloading analysis is demonstrated with the finite element/contact mechanics hybrid method applied to a 45 mm angular contact ball bearing.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA, Lewis Research Center, Rotordynamic Instability Problems in High-Performance Turbomachinery, 1988; p 373-387
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  • 5
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    Large-gap magnetic positioning system having advantageous configuration (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: A magnetic configuration was devised in which the positioned object is maintained in a stable orientation and position on one side of an opaque plane surface entirely by means of magnetic components on the other side of the plane. The system is effective with or without gravity, and can operate in any orientation. In this system, the positioned object need only contain a simple dipole magnet. The positioning components consist of a group of permanent magnets creating a magnetic field configuration which stabilizes the levitated dipole in all but one degree of freedom, and a magnetic position sensing and force feedback system to actively stabilize the object in the one unstable direction. The system utilizes very low power at equilibrium and can maintain gaps of 50 mm.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Research Center, International Symposium on Magnetic Suspension Technology, Part 2; p 941-953
    Format: text
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  • 6
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    Coarse-fine residual gravity cancellation system with magnetic levitation (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Aircraft flight along parabolic trajectories have been proposed and executed in order to achieve low cost, near free fall conditions of moderate duration. This paper describes a six degree of freedom experiment isolation system designed to cancel out residual accelerations due to mechanical vibrations and errors in aircraft trajectory. The isolation system consists of a fine motion magnetic levitator whose stator is transported by a conventional coarse motion stage. The levitator uses wide gap voice coil actuators and has the dual purpose of isolating the experiment platform from aircraft vibrations and actively cancelling residual accelerations through feedback control. The course motion stage tracks the levitated platform in order to keep the levitator's coils centered within their matching magnetic gaps. Aspects of system design, an analysis of the proposed control strategy and simulation results are presented. Feasibility experiments are also discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Research Center, International Symposium on Magnetic Suspension Technology, Part 1; p 473-492
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  • 7
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    Evaluation of Superplastic Forming and Weld-brazing for Fabrication of Titanium Compression Panels (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The two titanium processing procedures, superplastic forming and weld brazing, are successfully combined to fabricate titanium skin stiffened structural panels. Stiffeners with complex shapes are superplastically formed using simple tooling. These stiffeners are formed to the desired configuration and required no additional sizing or shaping following removal from the mold. The weld brazing process by which the stiffeners are attached to the skins utilize spot welds to maintain alignment and no additional tooling is required for brazing. The superplastic formed/weld brazed panels having complex shaped stiffeners develop up to 60 percent higher buckling strengths than panels with conventional shaped stiffeners. The superplastic forming/weld brazing process is successfully scaled up to fabricate full size panels having multiple stiffeners. The superplastic forming/weld brazing process is also successfully refined to show its potential for fabricating multiple stiffener compression panels employing unique stiffener configurations for improved structural efficiency.
    Keywords: MECHANICAL ENGINEERING
    Type: Welding, Bonding and Fastening, 1984; p 253-270
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  • 8
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    Eccentricity effects upon the flow field inside a whirling annular seal (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The flow field inside a whirling annular seal operating at a Reynolds number of 24,000 and a Taylor number of 6600 has been measured using a 3-D laser Doppler anemometer system. Two eccentricity ratios were considered, 0.10 and 0.50. The seal has a diameter of 164 mm, is 37.3 mm long, and has a clearance of 1.27 mm. The rotor was mounted eccentrically on the shaft such that the whirl ratio is 1.0 and the rotor follows a circular orbit. The mean axial velocity is not uniform around the circumference of the seal; near the inlet a region characterized by high velocity of the seal. By the exit, another region of high axial velocity is not uniform around the circumference of the seal; near the inlet a region characterized by high velocity of the seal. By the exit, another region of high axial velocity has developed, this time on the suction side of the seal. The magnitude and azimuthal distance of the migration increased with increasing whirl amplitude (eccentricity). Throughout the seal length, the azimuthal mean velocity varied inversely with the mean axial velocity. Increasing the whirl amplitude did not increase the magnitude of the azimuthal velocity at the seal exit.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Research Center, Rotordynamic Instability Problems in High-Performance Turbomachinery, 1993; p 101-112
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  • 9
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    Extraterrestrial surface propulsion systems (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Lunar traction systems, Mars oxygen production, and Mars methane engine operation were the three topics studied during 1992. An elastic loop track system for lunar construction operations was redesigned and is being tested. A great deal of work on simulating the lunar environment to facilitate traction testing has been reported. Operation of an oxygen processor under vacuum conditions has been the focus of another design team. They have redesigned the processor facility. This included improved seals and heat shields. Assuming methane and oxygen can be produced from surface resources on Mars, a third design team has addressed the problem of using Mars atmospheric carbon dioxide to control combustion temperatures in an internal combustion engine. That team has identified appropriate tests and instrumentation. They have reported on the test rig that they designed and the computer-based system for acquiring data.
    Keywords: MECHANICAL ENGINEERING
    Type: USRA, Proceedings of the 8th Annual Summer Conference: NASA(USRA Advanced Design Program; p 209-215
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  • 10
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    Rolling contact fatigue life of chromium ion plated 440C bearing steel (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Rolling contact fatigue (RCF) test specimens of heat treated 440C bearing steel were chromium ion plated in thicknesses from 0.1 to 8.0 micron and tested in RCF tester using 700 ksi maximum Hertzian stress. Heavy coatings, greater than about 5 micron in thickness, peeled off or spalled readily, whereas thin coatings, less than 3 micron thick, were tenacious and did not come off. Furthermore, significant improvement in RCF life was obtained with thin chromium ion plated test specimens. The average increase in B10 life was 75% compared with unplated 440C. These preliminary results indicate that ion plating is a promising way to improve bearing life.
    Keywords: MECHANICAL ENGINEERING
    Type: Advan. High Pressure O2(H2 Technol.; p 246-260
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