Issue link: https://resources.randsim.com/i/1481018
3 W H I T E P A P E R 2.1 Ab-T10 The Ab-T10 breakage model implemented in Rocky is a combination of the Ab-T10 approach, developed by JKRMC for the mining industry [4], and the Voronoi Fracture particle subdivision algorithm [5]. This approach uses arbitrary-shaped convex polyhedrons and therefore can preserve both mass and volume during the breakage process, unlike many other DEM computer codes where spherical particles are used. Empirical and probabilistic relationships are assumed to model the breakage process. The simulation process for breakage is described below. For every particle that is in contact with other particles and/or walls, the total specific contact energy, , is computed by summing the work done by the contact forces at all contact points in a particle during the loading period. In order to damage the particle, the total specific contact energy must be greater than the minimum breakage energy of the particle, , which is related to the particle size as: (1) (2) (3) where L is the particle size, e min,ref is the reference minimum specific energy for a reference particle size, and L ref is the reference particle size. Damage caused by successive collisions is taken into account by considering a cumulative value of the specific contact energy, e cum . If e t c is the instantaneous value of the specific contact energy at a given time t , the value of e cum will be updated only if e t c > e min and e c > e max , where e max is the maximum value of specific contact energy registered on the particle until the last time in which the value of e cum have been updated. When this happens, the update is made according to the expression: where e t c -∆t is the specific contact energy at the previous timestep. Whenever the particle is unloaded and the value of e t c decreases below e min , the value of e max is reset to zero, so a new cycle of loading may begin, in which the value of e cum will be able to increase again. The particle breakage probability, P(e cum ) , is calculated via the formula: