Processing of composites: Simulations of the draping of fabrics with updated material behaviour law

In the processing of composites, fibre reinforcement is draped over complex three dimensional geometries, yielding local variations in the fibre volum e fraction and fibre orientation with subsequent effects on the permeabilit y of the reinforcement during resin infiltration and on the properties of t he composite product. This study presents computer simulations of the drapi ng of fabrics by following a mechanical, finite element approach. The fabri c is considered as a solid continuum with mechanical properties and frictio n properties at interfaces. The problem is solved by applying an explicit d ynamic finite element analysis. In order to incorporate the large shear def ormation of fabric during draping, an updated material behaviour law was fo rmulated on the basis of changing fibre directions. The model was implement ed in a user computer subroutine and tested first in case-studies of simple in-plane shear where the predictions were also compared with experimental data from a picture frame type of shear test. Thereafter, numerical simulat ions focused on the draping of a fabric in a "hat" shaped mould, comprising a hemispherical cup with a wide flat rim. The predictions were compared wi th predictions from similar simulations without the updated material behavi our law, experimental data and predictions from a "fishnet" algorithm.