Actively stressed marginal networks

TL;DR

This paper investigates how motor-generated stresses influence the elasticity of disordered fiber networks, revealing critical behavior near marginal stability and the stabilizing role of motor activity.

Contribution

It introduces a combined theoretical and computational framework to understand motor effects on network mechanics, highlighting a scaling relation and the role of non-affine fluctuations.

Findings

Motor activity controls network elasticity near marginal stability.

Motor stresses can stabilize floppy networks, extending critical behavior.

Stiffness increases linearly with stress at high stress levels.

Abstract

We study the effects of motor-generated stresses in disordered three dimensional fiber networks using a combination of a mean-field, effective medium theory, scaling analysis and a computational model. We find that motor activity controls the elasticity in an anomalous fashion close to the point of marginal stability by coupling to critical network fluctuations. We also show that motor stresses can stabilize initially floppy networks, extending the range of critical behavior to a broad regime of network connectivities below the marginal point. Away from this regime, or at high stress, motors give rise to a linear increase in stiffness with stress. Finally, we demonstrate that our results are captured by a simple, constitutive scaling relation highlighting the important role of non-affine strain fluctuations as a susceptibility to motor stress.