Processing of Composites: Simulations of the Draping of Fabrics with Updated Material Behaviour Law

摘要

In the processing of composites, fibre reinforcement is draped over com- plex three dimensional geome~ries, yielding local variations jn the fibre volume fraction and fibre orientation with subsequent effects on the permeability of the reinforcement dur- ing resin infiltration and on the properties of the composite product. This study presents computer simulations of the draping of fabrics by following a mechanical, finite element approach. The fabric is considered as a solid con~inuum with mechanical properties and friction properties at interfaces. The problem is solved by applying an explicit dynamic fi- nite element analysis. In order to incorporate the large shear deformation of fabric during draping, an updated material behaviour law wa.'i formulated on the basis of changing fibre directions. The model was implemented in a user computer subroutine and tested first in case-studies of simple in-plane shear where the predictions were also comp"red with ex- perimental datu trom a picture frame type of shear test. Thereafter, numerical simulation~ 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 with predictions from similar simula- tions without the updated material behaviour law, experimental data and predictions from a "fishnet'. algorithm.