Paper number 273

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF THE FORMING OF THERMOPLASTIC SANDWICHES

O. Rozant, P.-E. Bourban, J.-A.E. Månson^*

Laboratoire de Technologie des Composites et Polymères (LTC)
*Ecole Polytechnique Fédérale de Lausanne (EPFL)
CH- 1015 Lausanne, Switzerland

Summary

Sandwich panels have been used extensively in the transportation industry. However, as geometric complexity increases, the manufacturing techniques require longer cycle times and significant manual labour. Press forming of initially flat thermoplastic sandwich panels is a new, potentially cost-effective route to obtain a complex part in a one-step process. Nonetheless the heterogeneous nature of the sandwich panels requires accurate control of the heating stage and the complex geometry of the final part can lead to wrinkling of the faces and local collapse of the core during forming. Thus, the potential for complex shape forming of thermoplastic sandwiches, based on a polyetherimide (PEI) foam core combined with PEI warp-knitted reinforced skins, has been investigated. An experimental approach associated with numerical simulations was used to define appropriate processing windows in terms of forming temperatures and to determine sandwich deformations during forming.

Keywords

deformation map, drapability, explicit FEM code, inverse method, processing window, sandwich, stamp forming, thermoplastic, knits.