The Dahl’s Model for the Inelastic Bending Behavior of Textile Composite Preforms. Analysis of its Influence in Draping Simulation

International audienc

The importance of taking into account behavior irreversibilities when simulating the forming of textile composite reinforcements

International audienc

Wrinkling and Bending during Forming of Multi-Layered Textile Composite

22nd International ESAFORM Conference on Material Forming (ESAFORM), Vitoria, SPAIN, MAY 08-10, 2019International audienceForming and wrinkling of composite textile reinforcements depends strongly of bending properties. The physics of bending of fibrous reinforcement is particular. Bending is related to the slip between the fibres. In addition the fibres are almost inextensible. Consequently the plate and shell standard approaches cannot be used. Numerical simulations of the forming can be done by introducing bending energy dependent on the bending moment and the curvature. In this way, it is possible to simulate wrinkles during shaping. To go further and simulate the overall deformation of the textile reinforcements in the thickness, a shell approach, different from the standard theories, is presented to correctly calculate the rotations of the normals of the textile reinforcemen

Bending and wrinkling of composite fiber preforms and prepregs. A review and new developments in the draping simulations

International audienceBending properties play a significant role in the forming of textile composites reinforcements, particularly in determining the shape of wrinkles. The physics related to the bending of fibrous reinforcements is specific. Bending is due to slippage between the fibers and since the fibers are quasi-inextensible, standard plate and shell theories are irrelevant. To measure bending characteristics, three experimental tests (and their variants) have been developed in the last decades, and efforts are currently devoted to extending and improving these tests. From their results, simulations can be performed by introducing a flexural energy related to the bending moment and the curvature. In particular, wrinkles during forming can be simulated. In the case of 3D modeling of thick reinforcements, the use of generalized continuum mechanics model is necessary because of the bending stiffness of each fiber and the slippage between fibers. In order to simulate textile reinforcements with shells, some shell approaches, different of the standard theories, can correctly calculate the rotations of textile reinforcement normals

Nouveau Procédé pour la Fabrication Haute Cadence de Pièces Composites base Thermoplastiques (Projet INCREASE)

International audienceA new direct process for the production of thermoplastic-based composite parts is proposed (C-RTM TP): injection in a partially closed hot mold containing the preformed dry reinforcement (3D preform), and controlled closure of the mold controlled in speed or force . The polymers used (amorphous or semi-crystalline) have a viscosity of between 25 and 75 Pa.s at Tf + 25 ° C. NCF reinforcements with a specific sewing thread compatible with the processing temperatures (up to 400 ° C) have been developed. A manufacturing pilot was set up around a bi-material horizontal electric press (600t) and a mold (400 °C) with 2 stations (impregnation / injection): INCREASE project.Un nouveau procédé direct pour la production de pièces composites à base thermoplastique est proposé (C-RTM TP) : injection dans un moule chaud partiellement fermé contenant le renfort sec préformé (préforme 3D), et fermeture contrôlée du moule pilotée en vitesse ou en effort. Les polymères utilisés (amorphes ou semi-cristallins) présentent une viscosité entre 25 et 75 Pa.s à Tf + 25°C. Des renforts NCF avec un fil de couture spécifique compatibles avec les températures de mise en œuvre (jusqu’à 400°C) ont été développés.Un pilote de fabrication a été mis en place autour d’une presse horizontale électrique bi matière (600t) et d’un moule (400°C) à 2 postes (imprégnation/injection): projet INCREASE