Frictional Property on the Granular Materials Surface

The friction characteristics of granular material are different from that of ordinary solid matter.By investigating the friction between two granular layers,we find:1) when the cover plate on which granular is stuck slides on the discrete granular layer relatively,the maximum friction reduces with the radius of granular increasing;2) the friction exerted on the cover layer relates to the discrete granular layers.It is increase with the layer number increasing,when the number of discrete granular layer is less than three.No significant change happens to the friction,when the number of discrete granular layer is increased to three or more than three.By fitting,the relation between F and R obeys this equation F=A+Bexp(-R/C).