An approach to model contact-friction interactions between beams within assemblies of fibers is presented in this paper in order to simulate the mechanical behaviour of entangled structures at the scale of individual fibers using the finite element method. The determination of contact elements associating pairs of material particles is based on the detection of proximity zones between beams and on the construction of intermediate geometries approximating the actual contact zone, and allowing to consider contact along zones of non-zero lengths. The penalty method for contact is improved by adjusting the penalty parameter for each contact zone, thus stabilizing contact algorithms and allowing to handle high numbers of contact elements. Applications to samples of textile materials involving few hundreds of fibers are presented to demonstrate the abilities of the method. The presented examples are related to the simulation of woven fabrics - computation of the initial configuration and application of test loadings - and the identification of the transverse mechanical behaviour of a twisted textile yarn.