Title: Large deformation DEM powder compaction simulations using a mechanically-derived contact model for adhesive elastic-plastic particles

Author (None): William Zunker, Massachusetts Institute of Technology

Abstract:

We present a mechanically-derived normal contact model able to capture the response of interacting adhesive elastic-plastic particles from low to high confinement. The model is built upon the Method of Dimensionality Reduction which allows the problem of a 3D axisymmetric contact to be mapped to a semi-equivalent 1D problem of a rigid indenter penetrating a bed of independent Hookean springs. Plasticity is accounted for by continuously varying the 1D indenter profile subject to a constraint on the contact stress. By considering the incompressible nature of this plastic deformation, the contact model is also able to account for multi-neighbor dependent effects, including formation of new contacts from outward displacement of the free surface. JKR type adhesion is recovered seamlessly by simply allowing the springs to stick to the 1D indenters surface. Additionally, we account for the rapid stiffening in the force-displacement curve under high confinement by allowing a superimposed bulk elastic response to be switched on. The contact model is implemented in the open-source discrete element software LIGGGHTS and its predictive capabilities are showcased on the industrially relevant problem of pharmaceutical tableting. Specific considerations regarding large deformation DEM simulations are discussed.