A general approach to the mechanical behaviour of woven fabrics at the scale of individual fibers is proposed in this paper. In order to simulate the behaviour of samples of woven fabrics, all fibers constituting these samples are taken into account in the model, and particular attention is paid to detecting and modeling of contact-friction interactions occuring within the assembly of fibers. The global problem is set within a large deformation framework, and is solved using an implicit algorithm. The developed methods are first employed to compute the unknown initial configuration of woven structures by reproducing the arrangement of yarns generated by the weaving process. Various loading cases can then be applied in order to identify the mechanical properties of such materials. Numerical results about samples made of nearly 400 fibers are given to show the ability of the method to handle representative examples. Very useful informations at the scale of individual fibers are obtained from these simulations and should help to understand the mechanisms at microscopic scale governing the complex nonlinear behaviour of woven fabrics.