Residual Strains in Thick Thermoplastic Composites: An Experimental Approach

Thermoplastic composites are currently investigated for application in windmill turbine blades for their recyclability. A suitable manufacturing technology for these thick structures is liquid resin infusion followed by in-situ polymerisation of Anionic Polyamide-6 (APA-6). During manufacturing of thick composite structures, temperature variations arise through the thickness, which can result in residual strains and through-the-thickness variations of properties, such as degrees of cure and crystallinity. The aim of this research was to develop experimental techniques that can be used to investigate these important effects in thick glass fibre (GF) reinforced APA-6 laminates. The used techniques comprise optic fibres with Bragg gratings, a volumetric dilatometry test based on the buoyancy principle, and the microVickers indentation test. The results as found in this research show that scaling up of GF/APA-6 composites in the thickness direction has no significant effect on the measured properties.Aerospace Materials and ManufacturingAerospace Engineerin