Modelling particles subject to permanent plastic deformations

A plastic wear model for ductile materials was recently developed within the supervisor’s group, based on the discrete element method (DEM). An initial model developed for flat

surfaces [1] has since been extended to arbitrarily shaped closed surfaces representing abradable particles. Each particle is essentially a multi-sphere clump in which the non-interacting constituent spheres are arranged to form a hollow shell. A constituent sphere is displaced in the direction of the local normal to the surface once a material yield criterion has been met. This has been implemented in a fork of the open-source LAMMPS [2] code.

This implementation, which enables one form of permanent change of a particle’s shape, can be extended to another: plastic deformation. Even in dense sheared granular systems, the contact network is constantly changing, i.e., interparticle contacts are highly transient [3]. This raises the question of whether elasto-plastic contact models, e.g., [4-5], which retain no memory of plastic deformation once a contact has been lost in the simulation, are suitable for all scenarios.

This project will initially extend the simulation framework developed for particle abrasion to capture plastic deformation. This framework will then be applied to explore the role of plasticity in granular systems, and assess the scenarios in which simpler elasto-plastic contact models can give acceptable results.

Informal queries from potential applicants can be directed to Dr Kevin Hanley (k.hanley@ed.ac.uk).

References

[1] Capozza, R. & Hanley, K.J. (2022): A comprehensive model of plastic wear based on the discrete element method. Powder Technology, 410, 117864

[2] Thompson, A.P. et al. (2022): LAMMPS - a flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales. Computer Physics Communications, 271, 108171

[3] Hanley, K.J., Huang, X., O’Sullivan, C. & Kwok, F. C.-Y. (2014): Temporal variation of contact networks in granular materials. Granular Matter, 16, 41–54

[4] Luding, S. (2008): Cohesive, frictional powders: contact models for tension. Granular Matter, 10, 235–246

[5] Thakur, S.C., Morrissey, J.P., Sun, J., Chen, J.F. & Ooi, J.Y. (2014): Micromechanical analysis of cohesive granular materials using the discrete element method with an adhesive elasto-plastic contact model. Granular Matter, 16, 383–400

The University of Edinburgh is committed to equality of opportunity for all its staff and students, and promotes a culture of inclusivity. Please see details here: https://www.ed.ac.uk/equality-diversity

Minimum entry qualification - an Honours degree at 2:1 or above (or International equivalent) in a relevant science or engineering discipline, possibly supported by an MSc Degree. Further information on English language requirements for EU/Overseas applicants.

Applications are welcomed from self-funded students, or students who are applying for scholarships from the University of Edinburgh or elsewhere.

Further information and other funding options.