SIMULATION OF AGGLUTINATES FORMATION

摘要

Micrometeorites that continuously impact on the lunar surface are responsible for creating agglutinates which are uniquely irregular, jagged and high porosity. Due to process of agglutinates formation, the amount of agglutinates in lunar soil can be used to estimate the exposure history of the soil by using a lunar soil evolution model. Using commercially available simulation software called the PFC2D~(TM), we can simulate the mechanical behavior of a system of particles in general. In the companion paper [1], the lunar agglutinates are simulated using the parallel-bond model which allows us to incorporate the resistance to moment, and the same approach is taken here. In this paper, we study the formation of agglutinates by simulating the initial lunar surface soils with no agglutinates, and then generating small particles (<20 μm for example) with very high velocities (>5 km/sec for example) impacting the surface lunar soil particles. The kinetic energy associated with an impacting micrometeorite is high enough to fragment/pulverize the coarse particles and the agglutinates and also produce the crater ejecta. In this analysis the equation developed by O’Keefe and Ahrens (1977) is used to estimate the volume of melt.