Fix_Abrasion: Plastic wear of arbitrarily shaped surfaces and particles in LAMMPS
The bulk dynamics of granular systems are significantly affected by the shape of the constituent particles.  As an added, but necessary, complication, particle shape can change over time through the process of abrasion.  However, the current LAMMPS implementation does not allow for abrasion to be captured. This represents a major shortcoming, and area of interest, as in reality all granular particles abrade and change shape to some extent.  Hence, this current research proposes to implement abradable non-spherical particles into LAMMPS through a new fix abrasion. Here, particle topologies are represented using the existing LAMMPS data structures - vertices by discrete spherical atoms, edges by bonds, and facets by angles. To model the abrasion, atoms are displaced normally to the particle’s surface, when subject to a force exceeding a material yield criterion, altering its shape and reducing its volume.  In this presentation, the current implementation is summarised and preliminary results are presented for a single non-spherical particle abraded isotropically by thousands of impacting spherical grains.
References 1.  H. Tao, B. Jin, W. Zhong, X. Wang, B. Ren, Y. Zhang, and R. Xiao, “Discrete element method model- ing of non-spherical granular flow in rectangular hopper,” Chemical Engineering and Processing: Process Intensification, vol. 49, pp. 151–158, Feb. 2010. 2.  G. Lu, J. R. Third, and C. R. Mu ̈ller, “Discrete element models for non-spherical particle systems: From theoretical developments to applications,” Chemical Engineering Science, vol. 127, pp. 425–465, May 2015. 3.  M. K. Saeed and M. S. Siraj, “Mixing study of non-spherical particles using DEM,” Powder Technology, vol. 344, pp. 617–627, Feb. 2019. 4.  T. Szab ́o, G. Domokos, J. P. Grotzinger, and D. J. Jerolmack, “Reconstructing the transport history of pebbles on Mars,” Nature Communications, vol. 6, p. 8366, Oct. 2015. Number: 1 Publisher: Nature Publishing Group. 5.  T. Weinhart, J. Lechman, and T. P ̈oschel, “Fragmentation and abrasion in granular matter systems,” Computational Particle Mechanics, vol. 8, pp. 1003–1004, Nov. 2021. 6.  R. Capozza and K. J. Hanley, “A comprehensive model of plastic wear based on the discrete element method,” Powder Technology, vol. 410, p. 117864, Sept. 2022.