On the physical interpretation of the Kawakita and Adams parameters derived from confined compression of granular solids

The objective of this paper was to investigate the physical significance of the Kawakita and Adams parameters derived from the compression of some granular solids. Four model granules of different expected deformation behaviour were prepared by varying the composition and porosity of the granules. The granules were nearly spherical and of similar size and showed a variation in mechanical properties in terms of their elasticity, plasticity, fracture strength and brittleness. Due to the size and shape of the granules, compression due to granule rearrangement was generally limited. The Kawakita a parameter approximated the maximal engineering strain of the granular solids and both the Kawakita a and b− 1 parameter reflected the plasticity of the granules. The Adams parameter τ0 seemed to reflect the initial cracking of granules. Thus, the combined use of the Kawakita parameters a and b− 1 and the Adams parameter τ0 may give a comprehensive representation of the compression behaviour of granular solids.

Graphical abstractThe objective of this paper was to investigate the physical significance of the Kawakita and Adams parameters derived from the compression of some granular solids. The granules were nearly spherical and of similar size and showed a variation in mechanical properties in terms of their elasticity, plasticity, fracture strength and brittleness. The Kawakita a parameter approximated the maximal engineering strain of the granular solids and both the Kawakita a and b− 1 parameter reflected the plasticity of the granules. The Adams parameter τ0 seemed to reflect the initial cracking of granules.Figure optionsDownload full-size imageDownload as PowerPoint slideSEM-pictures of cross-section surfaces from tablets produced at 50 MPa from microcrystalline cellulose granules of a) low porosity and b) high porosity.