Energy Dissipation in Complex Time-Dependent Interactions

Abstract

Granular damping elements (GDEs) are promising tunable systems for energy absorption, vibration isolation, and damping applications. Their behaviour is governed by complex particle–particle interactions, including frictional sliding, inelastic collisions, and the formation of force-chain networks. This study investigates the influence of particle properties and casing stiffness on the static and dynamic response of GDEs using a combined approach of Discrete Element Method (DEM) simulations and experiments. Numerical simulations were conducted on monodisperse assemblies of metallic-like and polymer-like particles with varying diameters. The results show that energy dissipation is strongly linked to the evolving contact network topology, coordination number, sliding ratio, and particle compliance. Although softer particles exhibit higher absolute energy dissipation due to increased deformation, the specific damping capacity remains relatively consistent across cases, suggesting that frictional contact mechanics dominate the dissipation process. Experimental tests were performed using catenoidal thermoplastic polyurethane (TPU) casings of different wall thicknesses filled with glass beads. The results indicate that casing stiffness significantly influences both dynamic stiffness and damping behaviour. More compliant casings allow greater relative particle motion, leading to increased energy dissipation. However, they also exhibit higher dynamic stiffness, which in turn affects the system’s natural frequency. Overall, the findings demonstrate that dynamic stiffness and damping in GDE systems are inherently coupled and cannot be independently optimised. These results provide valuable insights for the design of next-generation granular damping systems with enhanced and tunable energy dissipation performance.