Abstract
Friction coefficient of a rigid body sliding on a powder layer was measured. This is a model to explain the small apparent friction coefficient exhibited debris avalanches. In experiment, flour was mainly used as the powder material and metal disks used as the rigid body that slides a powder layer.As a result, it was found that friction coefficient became small at a higher speed than critical value. The obtained friction coefficient was smaller than the normal friction coefficient between rigid bodies. In addition it was confirmed disk was floating over that speed from observation of sliding marks.
“Dynamic pressure model” is proposed as the mechanism providing force to float a disk. The critical speed derived from this model is consistent with experimental results.
