A reproducible continuous production process for straight, different reinforced (UD and NCF) fibre composite structures could be demonstrated on basis of the predominantly low deviation of the characteristic mechanical values from the aimed values. The partially higher deviations can be attributed to an increased pore content in the material. When introduced into a series production, process adaptations (e.g. preform guidance system and injection method) lead to an improvement of the material quality. As a result, better material properties compared to the target values can be expected, especially for compressive load. According to the resin manufacturer, the interlaminar shear strength can be increased by additives, which is expected to further improve the mechanical properties.
The flame retardant is identified to influence the stability of the process. Without flame retardant a stable process could be shown and the requirements for smoke and toxicity are met, while the flammability does not meet the requirements of AITM. It is recommended to check the addition of a considerably reduced quantity of the flame retardant for reaching the flammability requirements. The same material quality has been proven for a scale-up in complexity from a flat (t=4mm) to the C-profile (t=2mm). The deviating characteristic values of the profile flanges are expected to reach a reproducible level by adapting the manufacturing process to a series production as described above.
The textile is identified to influence the stability of the manufacturing process for curved profiles. No stable process could be shown. Through a previous successful introduction of a curved profile as a bumper in the series production for automotive application under the leadership of Thomas Technik, a wealth of experience regarding the radius pultrusion is available. Therefore, the issues occurring here in the project Aeropul, can be traced back to the textile preform. During the production of the bumper, the profile is curved in the thickness direction of the laminate, while the curvature of the profile in Aeropul is in the same plane as the textile. This leads to accumulations of the NCF at the inner radius and to excessive pull-off forces. Biaxial and multiaxial fabrics (without any 0° direction) could be used in series production and the 0° fibres could be added well aligned as rovings to prevent material accumulations.
Limitations of the pultrusion process were identified and analysed in regard to material, geometry, and quality inspection. All achieved information are summed up in a review for technology readiness level 2 and 3.
