MICROSCOPIC MECHANICS OF FIBER NETWORKS

We report simulations of two-dimensional fiber networks of random geom etry. The stress distribution along a fiber agrees with the mean-field Cox prediction, but the stress transfer factor is determined by the p roperties of the whole fiber and not by just the local segment stiffne ss as suggested by micromechanical models. This leads to a linear dens ity dependence of the Young's modulus of a network. The initial loss o f stiffness at small strain can be explained with an exponential frequ ency distribution of microscopic stresses, and the asymptotic stiffnes s at large external strain agrees with mean-field predictions. The sim ulated behavior is independent of the microscopic fracture mechanism i n both regions.