Static Fatigue and Delayed Effects in Sand and Lunar Regolith

摘要

Time and rate effects play an important role in processing of granular materials. It is a known phenomenon that granular soils (sand, gravel) subjected to dynamic in situ compaction exhibit a delayed increase in cone penetration resistance. A hypothesis is suggested that this time-dependent effect is caused by the stress corrosion cracking of the micro-morphologic features on grain surfaces at the contacts between the grains. Lunar regolith is likely to be strongly affected by this phenomenon, as regolith grains have rich surface morphology due to absence of water and atmosphere in lunar environment.