Contribution for analysing the intra-ply yarn sliding mechanism in preforming of the woven fabric

International audienceManufacturing complex composite part via Liquid Composite Molding (LCM) processes involves preforming dry textile perform before injecting the liquid resin. The defect that may be encountered within the textile structure during preforming step decreases the expected mechanical properties of the composite part. The intra-ply yarn sliding is a defect frequently observed during preforming of a woven preform but its mechanism is far from being fully understood. In this paper, a contribution for analyzing the mechanism of this defect and the influencing process parameters is presented. This analysis is based on an experimental study performed for one ply carbon fabric using a hemispheric punch. The effect of the ply orientation and blank holder force on the fabric behavior during preforming is evaluated regarding the required preforming force and yarn slippage. For the performed tests, it was obvious the impact of these two factors on the fabric behavior. The slippage phenomenon occurred in zones with low shear angles, for specific ply orientation. The fabric behavior has been analyzed by considering the evolution of the yarn tension which is related to the contact shear stress induced by sliding the fabric across the die and blank holder during preforming. Using an analytical model for the yarn tension in friction sliding, the influencing ply geometry and process parameters have been identified. Based on this analysis a solution relative the ply geometry to reduce the yarn tension is examined

Contribution for analysing the intra-ply yarn sliding mechanism in preforming of the woven

Manufacturing complex composite part via Liquid Composite Molding (LCM) processes involves preforming dry textile perform before injecting the liquid resin. The defect that may be encountered within the textile structure during preforming step decreases the expected mechanical properties of the composite part. The intra-ply yarn sliding is a defect frequently observed during preforming of a woven preform but its mechanism is far from being fully understood. In this paper, a contribution for analyzing the mechanism of this defect and the influencing process parameters is presented. This analysis is based on an experimental study performed for one ply carbon fabric using a hemispheric punch. The effect of the ply orientation and blank holder force on the fabric behavior during preforming is evaluated regarding the required preforming force and yarn slippage. For the performed tests, it was obvious the impact of these two factors on the fabric behavior. The slippage phenomenon occurred in zones with low shear angles, for specific ply orientation. The fabric behavior has been analyzed by considering the evolution of the yarn tension which is related to the contact shear stress induced by sliding the fabric across the die and blank holder during preforming. Using an analytical model for the yarn tension in friction sliding, the influencing ply geometry and process parameters have been identified. Based on this analysis a solution relative the ply geometry to reduce the yarn tension is examined

Numerical models of fabric behaviour using hybrids discrete elastic and hypoelastic modelling

This paper present two hybrids discrete continuous models for the simulation of woven fabric reinforcement preforming via explicit finite element analysis. There approaches are based 1D elements on a beam or nonlinear connectors, and 2D element account for shearing resistance of the fabric. The first developed model is built using linear and nonlinear connectors to take into account the tensile stiffness of the fabric, and a shell elastic isotropic element. The second model is based on nonlinear elements and the hypo-elastic behaviour. The determination of the material parameters is straightforward from tensile and bias extension tests. These proposed approaches have been implemented in the ABAQUS explicit finite element programs via subroutine VUMAT. There models allows the simulation of industrial part forming in a reasonable computational time. Simulations of the hemispherical shape of woven fabric 48600 C1300 have been implemented to highlight the performance of these model