The Investigations On Electrical Properties Of Granular Materials

Granular materials have all kinds of peculiar physical phenomenon In order to study granular materials,physicists adopted various means such as stirring,rolling,vibration etc,and obtained great achievements.In recent years,physicists have studied granular materials by means of using electricity properties.This method has some advantages compared to thes others.For example it is easy to get the measurements of electrical parameters.And the measurement process did not affect the internal structure of system.Electrical parameter is a parameter that changes as quickly ab possible,it reflect the system'S Status all the time.In this paper,the resistances of uniform balls pile under constant current before and after disturbance have been measured.Reached the followin conclusions:1.The resistance distribution was measured in different conditions.For example:different heap size,different diameter of steel balls and different packing state.The resistance of heap is not a fixed value,but it has narrow established distribution.It is only several hundred ohms in the close packed state But once disturbed,the close packed state will be destroyed,the density of the heap is not changed in macro,but the resistance of heap increased two orders ofmagnitude.If the resistance of heap is bigger in close packed state,it is also bigger after disturbed.2.After disturbed,the resistance decrease exponentially.For different heap size or different diameter of steel balls,the Index size is not the same.3 . Time series correlation dimension has been constructed by using perturbation resistance of the heap after disturbed.the size of lmap and the diameter of the steel have little effect with the correlation dimension.The time series of resistance has fractal characteristics.4·Through statistical means,we found that the size of resistance changed before and after disturbance and its frequency has power-law relationship Power law is to judge whether a system is self-organized critical state.so the steel heap we studied exist self-organized criticality characteristic.But the conditions that the self-organized criticality existed need more researches...