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Numerical derivation of a normal contact law for compressible plastic particles

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journal contribution
posted on 03.04.2020, 15:45 by Ben D. Edmans, Csaba I. Sinka

A new contact law is proposed to describe the behaviour of plastically compressible particles. The law was derived from contact simulations in which a general continuum constitutive model, the von Mises Double Cap (VMDC) model, was introduced to represent the particle material behaviour, allowing distinct dilatory, shearing and densification plastic flow regimes. Elastic and plastic properties were prescribed as functions of density. Parametric studies were conducted covering the parameter space of published experimental data for a range of pharmaceutical powders and granules.

The analysis showed plastic zones corresponding to the three flow regimes developing within the particle, with size, shape, location and onset conditions being dependent on the strength ratios of the constitutive model. The contact law established combines an initial quasi-linear region followed by an exponential hardening region, arising from the initiation, growth and hardening of plastic zones, and the development of dense and stable load-bearing structures.

The outcome of these studies is a new contact law, relationships for predicting contact law parameters from material parameters for both loading and unloading, and guidelines for the analytical treatment of plastic compressibility in particle contact. The contact law can be employed in discrete element and homogenisation models to predict macroscopic properties of porous granular materials, while the analytical framework and qualitative findings can be used in the design of granules.

History

Author affiliation

Department of Engineering

Version

AM (Accepted Manuscript)

Published in

Mechanics of Materials

Publisher

Elsevier BV

issn

0167-6636

Acceptance date

16/12/2019

Copyright date

2019

Available date

19/12/2019

Publisher version

https://www.sciencedirect.com/science/article/pii/S0167663619306829

Language

en