On the validity of representation of the inter-particle forces of a polymer-colloid cluster by linear springs.

We have investigated the validity of the popular assumption of identical linear spring (ILS) in polymer-colloids aggregated clusters. The ILS assumption suggests that all inter-particle bonds in an aggregated cluster of polymer chains and colloid particles can be represented by identical linear springs. The assumption has been challenged by several experiments that showed the bond stiffness varies across the cluster based on the connectivity of their associated particles. Yet, the predictions of the computational models that used ILS assumption are surprisingly well-aligned with the experiments in some materials. By coupling the coarse-grain Brownian dynamics simulation to a Multi-body dynamics model, a systematic pathway for analyzing the effect of connectivity of particles on elasticity of polymer-colloids aggregated clusters is presented. ILS assumption is found to be valid for systems with a stress path formation mechanism such as close-packed polymer-colloid clusters. We found the assumption irrelevant in systems with wave-like stress distribution mechanism, such as with granular materials, sand piles and jammed systems. Keywords Mechanics; polymer-colloid clusters; Identical springs assumption. [ABSTRACT FROM AUTHOR]