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

A R Labanieh,D Soulat,P Ouagne,C Garnier,O Dalverny

doi:10.1088/1757-899x/460/1/012008

Abstract

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.

Highlights

Forming machine Experimental preforming machine developed at the GEMTEX laboratory [18], [19], which is illustrated in Fig 1, is used to conduct the preforming tests
The behavior of the “HexForce 48600 U 1250” carbon woven fabric during the friction-based blank-holders preforming process with a hemispheric-shaped punch was conducted with a particular attention given to the observation of the occurrence of the intra-ply yarn sliding defect
A higher preforming force is required to form the ply-45. This higher force is associated to the occurrence of the intra-ply yarn sliding defect on the holder corner along the radial yarns in the non-sheared zone

Summary

RESULT

The mean value of the recorded force is presented on the graph with error bars pointing out the standard deviation of the measurements The blank-holder, the transversal yarns accumulate creating a high density zone This accumulation of the yarns increases the inter-yarn contact pressure between the two interlaced yarn sets on the crossing areas leading to stop the yarn slippage. There is no gap between the longitudinal yarns and the dots placed on the transverse yarns remain aligned along the longitudinal yarns axis

ANALYSIS AND DISCUSSION

SOLUTION

Findings

CONCLUSION