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.

International audienceThe unexpected degradations of current carrying capacity of Cable-In-Conduit Conductors are attributed to be mechanical in origin Nb3Sn. As a result, the prediction of conductor's performances asks for the assessment of the local strain state of the Nb3Sn superconducting strands inside cables. For this purpose, a finite element modeling, specially developed for the simulation of cable mechanics, is presented in this paper. The presented mechanical model allows simulating the conductors' service life from manufacturing to operating conditions by describing the evolution of strains and stresses within each individual strand. The distributions of axial strains within strands, obtained from simulation results of both thermal and Lorentz loadings, could help characterize the influence of design parameters

International audienceIn this paper we propose a finite element approach which simulates the mechanical behaviour of beam assemblies that are subject to large deformations and that develop contact-friction interactions. We focus on detecting and modeling contact-friction interactions within the assembly of beams. Contact between beams--or between parts of the same beam in the case of self-contact, is detected from intermediate geometries defined within proximity zones associating close parts of beam axes. The discretization of contact-friction interactions is performed on these intermediate geometries by means of contact elements, constituted of pairs of material particles which are predicted to enter into contact. A 3D finite strain beam model is used to represent the behaviour of each beam. This model describes the kinematics of each beam cross-section using nine degrees of freedom, and is therefore able to represent plane deformations of these cross-sections. Algorithms are proposed to solve the global nonlinear problem using an implicit scheme, under quasi-static assumptions. Simulation results of the tightening and releasing of knots made on monofilament and multifilament yarns are shown as an application. Straight fibers are first twisted together to make a yarn, before suitable conditions are applied to their ends to form and tighten the knot. Tightening forces are finally released to obtain an equilibrium configuration of the knot without external forces