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A Discrete Element Model of High-Pressure Torsion Test to Assess the Effect of Particle Characteristics in the Interface

Lookup NU author(s): Chao Zhang, Dr Sadegh NadimiORCiD, Dr Sadaf MaramizonouzORCiD, Dr David MilledgeORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Sand particles have been used since the early stages of the railway industry to increase adhesion at the wheel-rail contact. However, there is a limited understanding of how sand particle characteristics affect the tribological performance of the wheel-rail contact. In this work, the high-pressure torsion test used as a small-scale simulation of the interface is numerically modelled using the discrete element method (DEM). The DEM model is then utilised to investigate the effect of different particle characteristics on the frictional performance of wheel-rail contact which can provide more insight on micromechanical observations. The effects of various particle characteristics including size, number, the number of fragments the particles break into, and the parameters defining the behaviour of the bonds between particle fragments on the coefficient of traction (CoT) are systematically investigated. Results show in dry contacts the coefficient of traction decreases when the size or number of sand particles increases. This can be attributed to the formation of weak shear bands between the fragments. It is also found that the CoT is more sensitive to the stiffness of the bond between the fragments of a broken particle compared to the strength of the bond. A limiting value for bond strength was identified, beyond which the sand particles exhibited ductile behaviour rather than the expected brittle fracture. The findings from this study can be useful for future research on adhesion management in wheel-rail contact and the modelling approach can be scaled up to the full contact.

Publication metadata

Author(s): Zhang C, Nadimi S, Maramizonouz S, Milledge D, Lewis R

Publication type: Article

Publication status: Published

Journal: ASME Journal of Tribology

Year: 2024

Volume: 146

Issue: 8

Print publication date: 01/08/2024

Online publication date: 02/04/2024

Acceptance date: 20/03/2024

Date deposited: 04/04/2024

ISSN (print): 0742-4787

ISSN (electronic): 1528-8897

Publisher: ASME


DOI: 10.1115/1.4065230

ePrints DOI: 10.57711/3gvh-sk52


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