COMPOSITES WEEK @ LEUVEN AND TEXCOMP-11 CONFERENCE. 16-20 SEPTEMBER 2013, LEUVEN EXPERIMENTAL ANALYSIS OF THE WARP INTERLOCK DEFORMABILITY DURING THE STAMPING PROCESS C. Dufour 1, 2, *, F. Boussu 1, 2 , P. Wang 1, 2 , D. Soulat 1, 2 1 Univ. Lille Nord de France, F-59000 Lille, France; 2 ENSAIT, GEMTEX, F-59100 Roubaix, France;*corresponding author: clement.dufour@ensait.fr ABSTRACT Several warp interlock structures have been woven, stamped and consolidated. In this study, the behaviour of non-impregnated thick 3D woven fabrics for deformability issues during the forming step using a hemispherical and a complex shape punch was analyzed. This work concerns experimental approaches conducted on performing step to see the influence of processes parameters (blank holder pressure, initial shape of the blank ....) on the forming feasibility and the resulted defects on preforms. With the emergence and use of 3D woven reinforcements structures, strengthened in the thickness, the objective of this study is to analyze the behaviour of three main families of 3D woven reinforcements also called "warp interlock" when forming by an experimental stamping process. A structure of each family with the same warp and weft densities and a similar thickness for all the structures was woven. In this study, a hemispherical punch was used to analyze warp and weft behaviour with the different structures. Different characteristic were analyzed: variation of the thickness, shear angle between warp and weft yarns, sliding of the external layers and material draw-in. INTRODUCTION Analysis of the deformability of non-impregnated reinforcements during the forming step has been studied in previous research works [1] but restricted to in plane characteristic analysis of thin textile preforms. The analysis of 3D warp interlock structures forming behaviour seems to be not yet studied. This work concerns experimental approaches [2-5] conducted on performing step to check the influence of processes parameters as blank holder pressure or initial shape of the blank on the forming feasibility and the resulted defects on preforms [6]. Numerical works, correlated with trials, allow to develop models just to reproduce the mechanical behaviour occurring during the forming step [8][9]. In these studies conducted on single or multiple fabric plies during the forming process, using dedicated tools to obtain the required final shape, the influence of reinforcement parameters on the forming capacity and the resulted defects has not been measured. Different types of fibre's raw material as E-glass, carbon, and more recently flax [10] have been used in forming behaviour studies. In Tavana et al. [11], the influence of 2D fabric weave diagram on the forming behaviour has also been studied.. showing that twill 2/1 weave pattern have the highest maximum yarn tensile stress at the same condition compared to the plain and twill 2/2 . By the same, the in-plane shear influence of the structure deformability has been conducted mainly on Non-Crimp Fabrics in two recent studies showing the ability of the reinforcement to be deformed by in-plane shear, out-of-plane bending and inter-ply sliding on a non-developable surface highlights [12][13].