Numerical modeling of collision of adhesive units: Stability and mechanical properties during handling

Abstract

Binary interaction between adhesive units formed from monodisperse spherical fines and carrier particles was studied with the discrete element method (DEM) in order to better understand phenomena such as lumping, bridging and flowability of adhesive units and mixtures. Three different surface coverage ratios (SCRs) representing different number of fines on the carrier, five different surface energies of interaction between fines and carrier, fifteen different relative velocities ranging from 0.04 m/s to 1.7 m/s were studied, with three replicates for each scenario. A total of over 700 independent simulations were conducted and stability ratios (retention, transfer and loss) and mechanical properties (coefficient of restitution) were determined. The critical velocity for the units, below which they tended to aggregate, was extracted. The units with high SCR and high surface energy were most stable and most cohesive. With increasing SCR, the fines tended to act as a damping pad, thus increasing the critical velocity. The adhesive units were found to be dynamic in nature and to undergo constant exchanges of particles. A detailed map of this behaviour was determined. The obtained findings constitute a first step towards the creation of multiscale DEM models for the mechanics of adhesive mixtures and provide insights into flowability and integrity of the mixtures.