Numerical prediction on frictional characteristics of binary mixtures consisting of flexible cylindrical particles and rigid spheres

Abstract

A Discrete Element Method (DEM) model for deformable cylindrical particles is established to investigate the Jenike shear process of binary mixtures consisting of flexible cylindrical particles and rigid spheres. The effects of the shape of flexible cylindrical particles and the proportion of cylindrical particles to spherical ones on the friction behavior of the mixture are discussed. Numerical results show that both the shear stress and internal friction angle increase with the aspect ratio (Ar) of the flexible cylindrical particles but decrease with the increase of the proportion of spherical particles. The role of Ar becomes slight when when the amount of spheres are much higher than the cylindrical particles (double or higher). For the mono-system containing flexible cylindrical particles of Ar=6 but without spheres, the strong interlocking packing structure leads to high shear stress and internal friction angle. It is indicated that the inclusion of rigid spheres disrupts the interlocking structure between flexible cylindrical particles and acts as a lubricant during the shear process. Based on the numerical results, a predictive correlation is established to predict the frictional characteristics of binary mixtures consisting of flexible cylindrical particles and rigid spheres considering the effect of particle shape and proportion. Furthermore, through a microscopic analysis of the numerical results, a deeper understanding of this phenomenon is gained. It is confirmed that the spherical particles can fill the voids between the flexible cylindrical particles, increasing the compactness of the mixture and promoting lubrication effects. The current research contributes to the better understanding of the mechanism of particle flow and is of paramount importance to improve the kinetic theories for complex granular flows.