Study Of Frictional Property On The Granular Materials Surface And The Factor Of Cavity Effect In Granular Matter

The properties of the friction on the granular materials surface and the cavity effects in granular matter are studied experimentally.We improved our experimental sets.The effects of the filling depth(viz,the depth of the cavity) and diameter of granular,diameter of the container and detecting rod on the cavity effects are acounted for.We found that the granular matter is influenced by the cavity's depth only and this relationship is independent of the diameter of the granular,the container and the detecting rod.In order to investigate the effects of the granular size and granular layer on the the property of granular sliding frition,we place a cover plate on the granular suface,then motor drags the cover plate on the granular layer,sensor automaticly measures the friction force acting on the cover plate.By investigating the friction experiment,we find:1) When the cover plate with granular stuck slides on the discrete granular layer relatively,the maximum friction decreases with the radius of granular increasing;2) The friction exerted on the cover layer relates to the discrete granular layers.It increases 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 increases to three or more than three.By fitting,the relation between F and R obeys this equationF=A+Bexp(-R/C).