Topology generation and quantitative stiffness analysis for fiber networks based on disordered spatial truss

Abstract

Fiber networks are essential functional materials, yet existing mechanical models only capture specific aspects of their mechanical properties. This paper proposes a general mechanical model for fiber networks based on pin-jointed bar assemblies. The topology and stress modes of the networks are generated through topology optimization. The model decouples and quantifies the contributions of entropy fluctuation, rearrangement, and fiber stress to the overall stiffness, explaining stiffness variations in actin networks and the differences in stiffness between thermal and athermal networks. It also replicates the experimental strengthening effects of prestressed fiber networks, theoretically justifying the power-law relationship between applied stress/strain and stiffness. A macroscopic 3D-printed experiment validates the model's ability to replicate stiffness variations and the rearrangement phenomena observed in collagen networks under compression and shear. This model enables a comprehensive investigation of the mechanical properties of fiber networks and contributes to the design of novel biomimetic metamaterials.