Experimental and numerical analyses of the mechanical behavior during draping of non-orthogonal bi-axial non-crimp fabric composite reinforcements

Abstract

Experimental analyses and modeling of the draping of composite fiber reinforcements generally concern textiles where the fiber directions are orthogonal in the initial state. However, there also exist biaxial NCF (Non-Crimp Fabric) reinforcements, where the two fiber directions are non-orthogonal. One objective of this paper was to revisit the picture frame and bias extension tests in the case of such non-orthogonal NCFs in order to determine the in-plane shear behavior which is different for positive and negative shear angles. A simulation approach based on stress resultant shell elements was developed for these reinforcements by taking into account the specific plane shear behavior of non-orthogonal NCF reinforcements identified by picture frame tests. It was shown that simulations of non-orthogonal NCF (0–45° and 0/135°) draping processes gave results that were consistent with experimental forming tests of these materials. In particular, the hemispherical forming of an NCF at 0–45° led to a very specific deformed shape with a good correlation between simulation and experiment. Some specificities of the 0–45° preforms, especially weak areas, have been highlighted both by simulation and experimentally.

Keywords

• Non-Crimp Fabric
• Non-orthogonal fibers
• Picture frame
• Bias extension test
• Draping