Planar random networks with flexible fibers.

The transition in random fiber networks from two-dimensional to three-dimensional planar structure driven by increasing coverage (total fiber length per unit area) is studied with a deposition model. At low coverage the network geometry depends on the scale-free product of fiber length and coverage while at high coverage it depends on a scale-free combination of flexibility, width and thickness of the fibers. With increasing coverage the roughness of the free surface decouples from the substrate, faster when fibers are stiffer. In the high coverage region roughness decreases exponentially with increasing fiber flexibility.