MICROSCOPIC MECHANICS OF FIBER NETWORKS

We report simulations of two-dimensional fiber networks of random geometry. The stress distribution along a fiber agrees with the mean-field Cox prediction, but the stress transfer factor is determined by the properties of the whole fiber and not by just the local segment stiffness as suggested by micromechanical models. This leads to a linear density dependence of the Young's modulus of a network. The initial loss of stiffness at small strain can be explained with an exponential frequency distribution of microscopic stresses, and the asymptotic stiffness at large external strain agrees with mean-field predictions. The simulated behavior is independent of the microscopic fracture mechanism in both regions.