Formability analyses of uni-directional and textile reinforced thermoplastics

The formability of two different composite materials used in aerospace industry has been investigated for a representative product geometry. The deformations during forming of carbon UD/PEEK and glass 8HS/ PPS blanks with a quasi-isotropic lay-up were analysed. The UD/PEEK product showed severe wrinkling in doubly curved areas, whereas the 8HS/PPS product showed better formability in those areas. This can be explained by the relatively high resistance against intra-ply shear for the UD/PEEK material. Moreover, the predictive capability of a finite element based simulation tool was shown. For both materials, the prediction of intra-ply shear and large wrinkles showed good agreement with those observed in the actual product. The smaller wrinkles in the products cannot be accurately represented with the element size used. However, predicted waviness at the corresponding locations could indicate critical areas in the product. The presented modelling approach shows great potential for application in the composite product design process. (C) 2013 Elsevier Ltd. All rights reserved.