Particle size effects on the contact force distribution in compacted polydisperse granular assemblies

Contact force distribution in a polydisperse granular assembly under uniaxial compaction is investigated using DEM simulations. In general, the contact force network generated in a compacted granular assembly is inhomogeneous. The effect of the relative particle size distribution on the nature of the contact force network in a compacted polydisperse granular assembly is investigated. The probability distribution and cumulative distribution of the normal contact forces for particles of different radii in a polydisperse granular assembly are analyzed. Distribution of the coordination number and the maximum force on each particle in a group of particles of the same size are also investigated. The study reveals that the larger particles have a higher probability of experiencing stronger contact forces than the smaller particles. The smaller particles in the assembly experience a lower maximum force and coordination number when compared to the larger particles. The small particles are observed to escape from the force chains by occupying the voids formed amongst the larger particles in the assemblies with considerable particle size variation. The particle size effect on the contact force distribution reduces as the size difference between the particles reduces. The knowledge of the distribution of the contact forces in a polydisperse assembly helps in estimating the probability of crushing amongst particles of different sizes.