Stability of bond clusters with a characteristic length scale for load distribution

Abstract: In biological materials, strong binding despite an applied load force is often based on clusters of dynamic bonds that share the load. Different macroscopic behaviors have been described depending on whether the load is shared locally or globally in the force-depended unbinding rate. Here we introduce and study a model in which the load is distributed over a characteristic length scale, introduced by an exponential decay. The model contains the local and global scenario as limiting cases and smoothly interpolates between them. We derive approximations in which some analytical results can be obtained. In particular, we derive rupture conditions and validate these with stochastic simulations. The model shows two main pathways for failure of the bond cluster, due to rupture of all bonds above a critical force and due to the formation of a critical crack, a large gap between closed bonds that spreads in both directions.