Linear stability and viscoelastic response in weakly jammed frictional granular systems

Abstract: Granular particles typically feature contact friction, which gives rise to various nontrivial properties of granular materials. In this work, we investigate the linear stability of static packings composed of frictional spheres, whose interactions are modeled using the discrete element method. We discuss a key difficulty in properly modeling static friction and address the problem of identifying rattlers. We also explore the spectrum of the energy matrix, which governs the linear viscoelastic response of the system. The intermediate- and high-frequency regimes of the spectrum remain qualitatively independent of both the friction coefficient and the packing fraction.