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  • Fluid Mechanics and Thermodynamics  (1)
  • Space Sciences (General)  (1)
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  • 1
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    Discrete Element Method Simulation of a Boulder Extraction From an Asteroid (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.
    Keywords: Space Sciences (General)
    Type: NF1676L-18557 , ASCE International Conference on Engineering, Science, Construction and Operations in Challenging Environments; Oct 27, 2014 - Oct 29, 2014; St. Louis, MO; United States
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
  • 2
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    Flowability of JSC-1a (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: We have done a complete flowability characterization of the lunar soil simulant, JSC-1a, following closely the ASTM-6773 standard for the Schulze ring shear test. The measurements, which involve pre-shearing the material before each yield point, show JSC-1a to be cohesionless, with an angle of internal friction near 40 deg. We also measured yield loci after consolidating the material in a vibration table which show it to have significant cohesion (approximately equal to 1 kPa) and an angle of internal friction of about 60 deg. Hopper designs based on each type of flowability test differ significantly. These differences highlight the need to discern the condition of the lunar soil in the specific process where flowability is an issue. We close with a list not necessarily comprehensive of engineering rules of thumb that apply to powder flow in hoppers.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2009-215625 , E-16938
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
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