Discussions on the existing particle density distribution formed around a single plunger due to its penetration

Abstract

Existing particle density distribution formed around a plunger is discussed using X-ray radiographs. As a result, existing particle density is shown to propagate as a kind of dynamic wave in the powder layer. This suggestion is very interesting from the standpoint of the spatial particle density distribution in a powder layer. The main results of this study are as follows: 1. When a plunger is penetrated into a powder layer and is displaced in it, a periodical existing particle density distribution develops around the plunger. Such a density distribution can be regarded macroscopically as spatially uniform in regions relatively remote from the plunger, but periodically variable in the vicinity of the plunger head. 2. Analogous to wave phenomena, the low density zones manifest reflection at the walls, diffraction through a slit and interference between two slits. 3. It is pointed out that the rotational component of particle movement with regard to a macroscopic slip plane is a critical factor in determining particle density variations as well as in the phenomena of reflection and interference observed with the development of existing particle density distribution within a powder layer.