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  • Spacecraft Design, Testing and Performance  (5)
  • Instrumentation and Photography  (4)
  • 2000-2004  (9)
  • 1980-1984
  • 1
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    CM-2 Environmental/Modal Testing of SPACEHAB Racks (2001)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that will launch on shuttle mission STS-107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack-level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the shuttles.
    Keywords: Spacecraft Design, Testing and Performance
    Type: Research and Technology 2000; NASA/TM-2001-210605
    Format: application/pdf
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  • 2
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    Membrane Vibration Analysis Above the Nyquist Limit with Fluorescence Videogrammetry (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A new method for generating photogrammetric targets by projecting an array of laser beams onto a membrane doped with fluorescent laser dye has recently been developed. In this paper we review this new fluorescence based technique, then proceed to show how it can be used for dynamic measurements, and how a short pulsed (10 ns) laser allows the measurement of vibration modes at frequencies several times the sampling frequency. In addition, we present experimental results showing the determination of fundamental and harmonic vibration modes of a drum style dye-doped polymer membrane tautly mounted on a 12-inch circular hoop and excited with 30 Hz and 62 Hz sinusoidal acoustic waves. The projected laser dot pattern was generated by passing the beam from a pulsed Nd:YAG laser though a diffractive optical element, and the resulting fluorescence was imaged with three digital video cameras, all of which were synchronized with a pulse and delay generator. Although the video cameras are capable of 240 Hz frame rates, the laser s output was limited to 30 Hz and below. Consequently, aliasing techniques were used to allow the measurement of vibration modes up to 186 Hz with a Nyquist limit of less than 15 Hz.
    Keywords: Instrumentation and Photography
    Type: SEM X International Congress and Exposition on Experimental and Applied Mechanics; Jun 07, 2004 - Jun 10, 2004; Costa Mesa, CA; United States
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  • 3
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    An Innovative Manufacturing of CCC Ion Thruster Grids by North Carolina A&T's RTM Carbon/Carbon Process (2003)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Electric ion thrusters are the preferred engines for deep space missions, because of very high specific impulse. The ion engine consists of screen and accelerator grids containing thousands of concentric very small holes. The xenon gas accelerates between the two grids, thus developing the impulse force. The dominant life-limiting mechanism in the state-of-the-art molybdenum thrusters is the xenon ion sputter erosion of the accelerator grid. Carbon/carbon composites (CCC) have shown to be have less than 1/7 the erosion rates than the molybdenum, thus for interplanetary missions CCC engines are inevitable. Early effort to develop CCC composite thrusters had a limited success because of limitations of the drilling technology and the damage caused by drilling. The proposed is an in-situ manufacturing of holes while the CCC is made. Special low CTE molds will be used along with the NC A&T s patented resin transfer molding (RTM) technology to manufacture the CCC grids. First, a manufacture process for 10-cm diameter thruster grids will be developed and verified. Quality of holes, density, CTE, tension, flexure, transverse fatigue and sputter yield properties will be measured. After establishing the acceptable quality and properties, the process will be scaled to manufacture 30-cm diameter grids. The properties of the two grid sizes are compared with each other.
    Keywords: Spacecraft Design, Testing and Performance
    Type: HBCUs/OMUs Research Conference Agenda and Abstracts; 20; NASA/TM-2003-212207
    Format: text
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  • 4
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    Vibration Modal Characterization of a Stirling Convertor via Base-Shake Excitation (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The U.S. Department of Energy (DOE), Lockheed Martin (LM), Stirling Technology Company (STC), and NASA John H. Glenn Research Center (GRC) are currently developing a high-efficiency Stirling convertor for use in a Stirling Radioisotope Generator (SRG). NASA and DOE have identified the SRG for potential use as an advanced power system for future NASA Space Science missions, providing spacecraft onboard electric power for deep space missions and power for unmanned Mars rovers. Low-level, baseshake sine vibration tests were conducted on the Stirling Technology Demonstration Convertor (TDC), at NASA GRC's Structural Dynamics Laboratory, in February 2001, as part of the development of this Stirling technology. The purpose of these tests was to provide a better understanding of the TDC's internal dynamic response to external vibratory base excitations. The knowledge obtained can therein be used to help explain the success that the TDC enjoyed in its previous random vibration qualification tests (December 1999). This explanation focuses on the TDC s internal dynamic characteristics in the 50 to 250 Hz frequency range, which corresponds to the maximum input levels of its qualification random vibration test specification. The internal dynamic structural characteristics of the TDC have now been measured in two separate tests under different motoring and dynamic loading conditions: (1) with the convertor being electrically motored, under a vibratory base-shake excitation load, and (2) with the convertor turned off, and its alternator internals undergoing dynamic excitation via hammer impact loading. This paper addresses the test setup, procedure and results of the base-shake vibration testing conducted on the motored TDC, and will compare these results with those results obtained from the dynamic impact tests (May 2001) on the nonmotored TDC.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2003-212479 , E-14017 , AIAA Paper 2003-6096 , First International Energy Conversion Engineering Conference; Aug 17, 2003 - Aug 21, 2003; Portsmouth, VA; United States
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  • 5
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    Photogrammetry Methodology Development for Gossamer Spacecraft Structures (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Photogrammetry--the science of calculating 3D object coordinates from images-is a flexible and robust approach for measuring the static and dynamic characteristics of future ultralightweight and inflatable space structures (a.k.a., Gossamer structures), such as large membrane reflectors, solar sails, and thin-film solar arrays. Shape and dynamic measurements are required to validate new structural modeling techniques and corresponding analytical models for these unconventional systems. This paper summarizes experiences at NASA Langley Research Center over the past three years to develop or adapt photogrammetry methods for the specific problem of measuring Gossamer space structures. Turnkey industrial photogrammetry systems were not considered a cost-effective choice for this basic research effort because of their high purchase and maintenance costs. Instead, this research uses mainly off-the-shelf digital-camera and software technologies that are affordable to most organizations and provide acceptable accuracy.
    Keywords: Instrumentation and Photography
    Type: AIAA Paper 2002-1375 , 43rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference; Apr 22, 2002 - Apr 25, 2002; Denver, CO; United States|3rd AIAA Gossamer Spacecraft Forum; Apr 22, 2002 - Apr 25, 2002; Denver, CO; United States
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  • 6
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    Lessons Learned From CM-2 Modal Testing and Analysis (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS-107 in the SPACEHAB Double Research Module. The CM-2 flight hardware is installed into SPACEHAB single and double racks. The CM-2 flight hardware was vibration tested in the launch configuration to characterize the structure's modal response. Cross-orthogonality between test and analysis mode shapes were used to assess model correlation. Lessons learned for pre-test planning and model verification are discussed.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2002-211692 , NAS 1.15:211692 , E-13422 , Ninth International Congress on Sound and Vibration; Jul 08, 2002 - Jul 11, 2002; Orlando, FL; United States
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  • 7
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    CM-2 Environmental / Modal Testing of Spacehab Racks (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS 107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the Shuttle.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2001-210677 , NAS 1.15:210677 , E-12604 , Seventh International Congress on Sound and Vibration; Jul 04, 2000 - Jul 07, 2000; Garmisch-Partenkirchen; Germany
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  • 8
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    Dot Projection Photogrammetric Technique for Shape Measurements of Aerospace Test Articles (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Results from initial laboratory investigations with the dot projection photogrammetric technique are presented for three wind-tunnel test articles with a range of surface scattering and reflection properties. These test articles are a semispan model and a micro air vehicle with a latex wing that are both diffusely reflecting, and a highly polished specularly reflecting model used for high Reynolds number testing. Results using both white light and laser illumination are presented. Some of the advantages and limitations of the dot projection technique are discussed. Although a desirable final outcome of this research effort is the characterization of dynamic behavior, only static laboratory results are presented in this preliminary effort.
    Keywords: Instrumentation and Photography
    Type: AIAA Paper 2002-0532 , 40th AIAA Applied Aerodynamics Conference; Jan 14, 2002 - Jan 17, 2002; Reno, NV; United States
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  • 9
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    Laser Induced Fluorescence for Photogrammetric Measurement of Transparent or Reflective Aerospace Structures (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: To support the requirement for non- contacting measurement of polymer membrane structures a new technique based on the principles of photogrammetry has been developed and is described here.
    Keywords: Instrumentation and Photography
    Type: 49th Annual International Instrumentation Symposium (ISA); May 04, 2003 - May 08, 2003; Orlando, FL; United States
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