Manufacturing, microstructural and mechanical investigations of inverse hybrid composite laminates: Glass fiber-reinforced polyamide-6/aluminium

Inverse hybrid laminate consists of a metallic sheet alloy sandwiched between two fiber-reinforced thermoplastic composite layers. This class of structures could be tailored through the use of specific sub-components to achieve desired mechanical performance. The metal/composite adhesion is a common challenge in this hybrid laminates and strongly depends on its sub-components. The hybrid compound targeted in the present work consist of polyamid-6 thermoplastic reinforced with glass fibres, laminated to an aluminium sheet alloy. The metal/composite adhesion is ensured by a commercial monolayer adhesive film based on functionalized polypropylene, augmented with a mechanical treatment of the aluminium sheet surfaces.

Inverse hybrid laminates are manufactured under a controlled time, temperature and pressure cycle. The laminates microstructure is investigated using DSC and tomography imaging. Three-point bending, tensile and Interlaminar Shear Strength tests are conducted to evaluate their mechanical performance and failure modes. The mechanical performances and failure mechanisms of the hybrid laminates are compared to those of glass fiber reinforced polyamide-6 under both three-point bending and tensile tests. The structural hybrid lamination in conjunction with the enhanced metal/aluminium adhesion improves stiffness and the required load to failure, although its strength is lower. The dominated structural metal/composite interfaces within the hybrid laminates exhibit lower interlaminar strength compared to the glass fiber reinforce polyamide-6 composite.