Mechanics of composite networks with rope-like filaments

Crosslinked fiber networks form a critical part of biological systems. The cytoskeleton comprises of such networks formed by biopolymers such as actin, microtubules and intermediate filaments. They are vital for processes like cell motility while being responsible for the structural integrity of cells. While actin and vimentin networks have been thought to be two separate yet co-existing networks, recent advances indicate the presence of crosstalk and formation of interpenetrating networks. In this work, we develop a computational model to capture the mechanical behavior of such interpenetrating networks under shear strain. Using triangular lattice-based simulations, we construct networks consisting of Hookean and rope-like filaments with varying slack to study strain-stiffening and floppy to rigid phase transition. Rope-like filaments introduce novel strain-dependent constraints resulting in mechanical regimes due to competition between the stretching and bending modes of the two networks. We analyze how system parameters such as slack, network connectivity, and filament stretching/bending influence the onset of the mechanical phase transition.