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A macroscopic approach to simulate the forming behaviour of stitched unidirectional non-crimp fabrics (UD-NCF)

: Schirmaier, F.J.; Dörr, D.; Henning, F.; Kärger, L.


Composites. Part A, Applied science and manufacturing 102 (2017), S.322-335
ISSN: 1359-835X
Deutsche Forschungsgemeinschaft DFG
Deutsche Forschungsgemeinschaft DFG
Fraunhofer ICT ()

Thin composite shell structures manufactured from stitched unidirectional non-crimp fabrics (UD-NCF) in a liquid composite moulding process provide high lightweight design capabilities. For complex geometries, the forming process of the textile pre-products is challenging and requires intensive investigations to avoid defects like macroscopic wrinkling or fibre gapping. In contrast to biaxial engineering fabrics, UD-NCF has been investigated only sparsely in terms of its forming behaviour, both experimentally and numerically. To close this gap, a macroscopic forming simulation model for UD-NCF is proposed in this work, including a new non-orthogonal and linear strain measure for large strains and the corresponding nominal stress measure. To parameterize the constitutive laws and to investigate the multiaxial deformation behaviour of UD-NCF, supplementary off-axis-tension tests with optical strain measurement are performed in this work. The new forming simulation model is validated via forming simulation of a hemisphere test and of a preforming process of an automotive component.