The Role of Melting on Intimate Contact Development in Laser-Assisted Tape Placement of Carbon Fibre Reinforced Thermoplastic Composites

Abstract

Laser-assisted tape placement (LATP) and thermoplastic composites (TPCs) pre-impregnated (prepreg) tapes are a promising combination of technologies; given the in-situ capabilities of the TPCs and the high degree of automation achievable with LATP. However, laminate quality, measured as final void content, tends to decrease when increasing placement speed. Heating and consolidation windows in LATP of TPCs are very short, especially when increasing the placement speed. For TPCs, resin flow is heavily influenced by melt viscosity above melting temperature (Tm). Therefore, the degree of intimate contact (Dic) resulting from the compaction phase can be significantly influenced by the tape’s degree of melt at the end of the heating phase. Due to melting being a kinetically controlled process[1,2], both temperatures and times above Tm need to be considered. The relationship between the degree of melt, both through thickness and in time, prior to compaction and the final Dic has not been explored yet. In this study, the final Dic and degree of melt of a CF/PEEK tape as a function of heating power, heating length and placement speed will be evaluated and correlated. The experimental investigation will consist of calorimetric data on melting kinetics of the polymer, and LATP experiment runs with different process parameters. Simulations of the thermal history (see Figure 1) and melting in the heating phase will be performed and validated with experiments. The research aims to understand the melting behaviour of the tapes during the heating stage in LATP, its dependence on the process parameters, and how it affects the final Dic and laminate quality.