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Measuring the mechanical properties of small body regolith layers using a granular penetrometer

Astrodynamics 2023年第1期7卷 15-29页

作者： Bin Cheng Erik Asphaug Yang Yu Hexi Baoyin School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Lunar&Planetary Laboratory University of ArizonaTucsonAZ 85721USA School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

Small bodies in the solar system are known to be covered by a layer of loose unconsolidated soil composed of grains ranging from dusty sands to rugged *** geophysical processes have modified these regolith layers since their ***,the landforms on regolith-blanketed surfaces hold vital clues for reconstructing the geological processes occurring on small ***,the mechanical strength of small body regolith remains unclear,which is an important parameter for understanding its dynamic ***,regolith mechanical properties are key factors for the design and operation of space missions that interact with small body *** granular penetrometer,which is an instrument that facilitates in situ mechanical characterization of surface/subsurface materials,has attracted significant ***,we still do not fully understand the penetration dynamics related to granular regolith,partially because of the experimental difficulties in measuring grain-scale responses under microgravity,particularly on the longer timescales of small body *** this study,we analyzed the slow intrusion ofa locomotor into granular matter through large-scale numerical simulations based on a soft sphere discrete element *** demonstrated that the resistance force of cohesionlessregolith increases abruptly with penetration depth after contact and then transitions to a linear *** scale factor of the steady-state component is roughly proportionalto the internal friction of the granular materials,which allows us to deduce the shearstrength of planetary soils by measuring their force depth *** cohesion is included,due to the brittle behavior of cohesive materials,the resistance profile is characterized by a stationary state at a large penetration *** saturation resistance,which represents the failure threshold of granular materials,increases with the cohesion strength of the *** positive correlation pr

关键词： small body regolith granular penetrometer small body exploration granular dynamics

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An analysis of the chaotic motion of particles of different sizes in a gas fluidized bed

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Particuology 2008年第6期6卷 549-556页

作者： Y.Q. Feng A.B. Yu Lab for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering University of New South Wales Sydney NSW 2052 Australia

The dynamic behavior of individual particles during the mixing/segregation process of particle mixtures in a gas fluidized bed is analyzed. The analysis is based on the results generated from discrete particle simulation, with the focus on the trajectory of and forces acting on individual particles. Typical particles are selected representing three kinds of particle motion： a flotsam particle which is initially at the bottom part of the bed and finally fluidized at the top part of the bed; a jetsam particle which is initially at the top part of the bed and finally stays in the bottom de-fluidized layer of the bed; and a jetsam particle which is intermittently joining the top fluidized and bottom de-fluidized layers. The results show that the motion of a particle is chaotic at macroscopic or global scale, but can be well explained at a microscopic scale in terms of its interaction forces and contact conditions with other particles, particle-fluid interaction force, and local flow structure. They also highlight the need for establishing a suitable method to link the information generated and modeled at different time and length scales.

关键词： Fluidization Segregation Discrete particle simulation granular dynamics

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