Paper number 389

F.E. INVESTIGATION OF THE NON-CRIMP FABRICS COMPRESSIVE AND INTERLAMINAR BEHAVIOURS

S. Drapier¹ and M.R. Wisnom²

1Now at : Mechanical and Materials Engineering Department, SMS Division
École Nationale Supérieure des Mines de Saint-Étienne
158, cours Fauriel,42023 Saint-Étienne cedex02, France
E-mail : drapier@emse.fr
2Department of Aerospace Engineering, University of Bristol, University Walk
Bristol BS8 1TR ,United-Kingdom
E-mail : m.wisnom@bristol.ac.uk

Summary

This work aims first at relating the Non-Crimp Fabrics (NCF) compressive and InterLaminar Shear (ILS) behaviours to the constituents' characteristics. Also manufacturing guidelines to optimise NCF structure against these loadings are derived. The key of this FE modelling is to set the approach at an intermediary scale where geometrical imperfections can be represented along with adequate material non-linearities. This can be achieved only through the proper use of homogeneous equivalent media. A repeating cell is defined across the thickness and along a direction of a biaxial blanket. Results establish that the NCF compressive response is controlled by a mesoscopic instability closely related to the coupling of tows imperfections with the resin non-linear shear behaviour. Under ILS resin controls the NCF response, and indirectly both the presence of resin layers between tows and tow cross-sectional shape are shown to induce shear strain concentrations. Experiments carried out by partners give results which correlate very well with guidelines derived from the present approach.

Keywords

non-crimp fabrics composites, structure-property relation, non-linear finite element model, compression, interlaminar shear, shear strain concentration.