Colloquium: Irene Eby (ASM)

This study investigates the influence of layup temperature, layup speed, and compaction force on the tack behaviour of Hexcel Hitape® dry fibre material during the Automated Dry Fibre Placement (ADFP) process. Additionally, it also assesses the applicability of an existing tack model, developed for TX1100 dry fibre material, to the Hexcel HiTape®, possessing a different binder type and distribution and different fibre architecture. Tack force, which ensures layer adhesion in AFP manufacturing was evaluated using 90-degree peel tests. Initial analysis used a 2-level factorial design of experiments to evaluate main parameter effects. To investigate non-linear behaviour, this design was extended to a 3-level face-centred composite design of experiments. The results show that temperature is the most dominant factor affecting tack, with higher temperatures significantly increasing tack forces due to binder activation and polymer diffusion at the interface. Layup speed also had a notable influence, with higher speeds leading to increased tack forces, which contrasts with the inverse relationship predicted by the existing model. This is likely due to the material architecture of Hexcel HiTape, where faster speeds reduce binder seepage through perforations, allowing more binder to remain at the interface. Compaction force had a minor impact on tack behaviour. Additionally, while interaction effects between the parameters were analysed, they were not statistically significant at the 95% confidence level. The findings suggest that the independent contributions of temperature and velocity are key, but deviations from expected behaviour may be due to material-specific characteristics such as perforations and fibre structure. The behaviour of the material in relation to the statistically significant parameters show that there is non-linearity.To test the generalisability of the model, the existing tack model for TX1100 dry fiber was applied to Hexcel HiTape. The observed positive relationship between speed and tack, contrary to the TX1100 model’s inverse relationship, shows the need to adapt the model to Hexcel HiTape and indicates limitations in generalizing tack models across dry fiber materials. Additionally, fibre fraying of Hexcel HiTape® was observed during peel tests, marking a material-specific quality that warrants further investigation to quantify the effect, aiding in understanding the dry fibre material behaviour.

Supervisor: Dr. ir. DMJ (Daniël) Peeters