Comparison of DEM Simulation and Physical Experiments of Strongly Attractive Particle-Particle Interactions

Recent experiments by Eccleston and Miller, have directly measured strongly attractive particle-particle interactions by gluing 15 |j.m diameter Borosilicate glass spheres to the ends of cylindrical glass cantilevers and measuring the cantilevers' deflections as the particles are brought together and pulled apart. These experiments show a wide range of qualitative behavior of clusters of particles; the most curious of which is stick-slip, which would not be expected for force interactions that are between particles' centers of mass. We assume a van der Waals attractive force between macroscopic spheres and simulate the experiments using a Discrete Element Method DEM. It is found that the van der Waals force approximation accurately returns the values of the cantilever deflection measured in the experiment. We also find that the stick-slip behavior is recovered from the DEM model when the particles have a non-zero coefficient of friction.