All-thermoplastic sandwiches with composite faces and thermoplastic foam as core material present great potential for future automotive mass applications. They offer many advantages such as high specific bending stiffness, good insulation properties, high impact resistance,... Furthermore, the use of one single polymer throughout the sandwich brings on optimal face–core compatibility, enhanced recyclability and post-formability. The aim of this first part is to investigate the processing of thermoplastic sandwich structures with improved surface quality manufactured by isothermal compression moulding.

No abstract

This second part aims to investigate the modelling of the bending behaviour of all-thermoplastic sandwich structures with improved aesthetic properties, manufactured by isothermal compression moulding. The aesthetic thermoplastic sandwiches exhibit specific features such as thick multi-layered faces and significant core properties variation due to processing conditions. Considering these specific features, a three-step calculation methodology has been developed to determine an accurate analytic model, to predict the equivalent shear properties of the core after manufacturing and to take into account the influence of the glass veil layer used to improve the surface quality of the part. Finally, a finite element modelling of the linear elastic behaviour of a simply supported sandwich plate under a concentrated load is achieved to validate the proposed methodology.

Adaptive hybrid composites are materials in which actuators are embedded into polymer matrix composites. One particular class of these actuators are shape memory alloys (SMA). Thin wires ( = 200 jim) of NickelTitanium-Copper (nitinol) were incorporated into a glass-epoxy unidirectional laminate during lay-up. Then the whole structure s subjected to different curing procedures. The interfacial shear strength between the matrix and the nitinol wires in various structural states was determined by a micromechamcal test involving the interface directly -the drop test. Clamped-free (cantilever) beam method was used to evaluate the effect of actuation by heating the mtinol wires embedded into the composite. The comparison between the different composites points out first the leading role of the interfacial shear strength. On the other hand, it can be noted the occurrence of a self-trained two way shape memory effect.