Modeling of Binary Collision between Multisize Viscoelastic Spheres
An accurate new contact force model is proposed for describing the grain collision process. The linear and nonlinear contact force models and normal coefficient of restitution in different impact velocities has been studied. A new contact force model for describing the normal collision between two viscoelastic spherical particles has been suggested and the ability of this new model in predicting the correct behavior of normal contact has been confirmed. The constitutive equations of this model have been solved numerically and the result shows a better conformity with experimental result reported by Bridge et al.(1) than the previous models, such as the model presented by Brilliantov et al.(2) By using the suitable finite elements model, the stress and deformation of particles during the collision has been obtained and the result of the finite element model shows a good conformity with our new suggested contact force model in the case of elastic and viscoelastic contact. The behavior of normal coefficient of restitution in multisize spherical particles in different impact velocities and the effect of the size on it has been experimentally studied. In addition to our more suitable contact force model, we achieved some nice conclusions from our experimental data about the loss of energy during the multisize collision and effect of size difference on this loss.