(261b) Regimes of Impact-Induced Erosion of Particles of Varying Strength

Particle breakage is relevant to many applications, from pharmaceutical processing to jet printing to defense technologies. Fundamental understanding of particle behavior during and after impact as a function of particle strength and impact velocity is needed for process optimization. In addition, detailed information about the number, shape, size and velocity of resulting fragments is difficult to obtain, particularly at conditions of high impact velocity. Discrete element method (DEM) simulations provides the capability to simulate the physics of particle impact and breakup at the micro-scale. This work explores varying particle breakage behavior upon impact with a flat surface. Impacting particles are modeled as spherical agglomerates consisted of a number of smaller constituent particles held together via a constant adhesive force characterized by a surface energy. Under the influence of a wide range of impact velocities and particle surface energies, five distinct behavioral regimes – rebounding, resting, fragmentation, pancaking, and shattering – are identified. In the rebounding regime, the coefficient of restitution decreases linearly as impact velocity increases. In the fragmentation regime, the rebound velocity generally decreases with increasing fragment size. These trends are consistent with the experimental results obtained in the study of Hassani-Gangaraj et al. (2018). Some regimes are only present at certain velocities while the extent of these regimes varies with particle strength. The type of regime depends largely on how the impact force is transmitted and dissipated through particle-particle contacts within the agglomerate.

Hassani-Gangaraj, M.; Veysset, D.; Nelson, K.A.; Schuh, C.A. “Melt-Driven Erosion in Microparticle Impact,” Nature Communications 2018, 9, 1-7