Structure characterization on the vibration induced mono-sized hard sphere crystal and its dynamics by DEM modeling

In this paper,the ordering(Crystallization) of mono-sized sphere packing under three-dimensional(3D) interval vibration and batch-wised feeding was studied with numerical discrete element method(DEM) combined with the physical experiments.Through the characterization on the crystalline structure and the analysis on the micro-properties obtained numerically such as coordination number(CN),radial distribution function(RDF),angular distribution function(ADF),Voronoi/Delaunay void size distribution,force network and the dynamics formed during ordering,following conclusions can be drawn:(1) The crystalline obtained both numerically and physically all indicates {111}-oriented FCC structure,where the maximum packing density can reach 0.74;(2) There is a peak at CN=12 in the coordination number distribution curve,which implies that each particle in the hard sphere crystal has 12 neighbors in contact;the distributions for RDF and ADF show the long range correlation in radial distance and angle correlation among particles,which are the typical characteristics of the crystalline structure;the Voronoi/Delaunay void size distribution indicates the higher and narrower curve shifting to the left compared with non-crystal state,which means that the voids in crystalline structure are small and uniform;the force network among particles can identify the crystalline structure more intuitively,meanwhile,it's also indicated that the in-plane forces and inter-plane forces coexist in the crystal,and the latter is smaller than the former;(3) The variation of dynamic information such as the velocity field and the force field all indicates that once the ordered structure formed during crystallization,it will move as a whole part,which served as the template for the other particles,i.e.as the nucleus in the crystallization.