Deconsolidation of thermoplastic prepreg tapes during rapid laser heating

In this study, the effect of rapid laser heating, which is typical during laser-assisted fiber placement (LAFP), on the micro- and meso- structure of the thermoplastic tape was investigated. Thermoplastic tapes were heated above the melting temperature with different heated lengths (30 and 80 mm and heating times (0.2 and 0.8 s) in a dedicated experimental setup. In-situ and ex-situ characterization techniques were used to observe the differences between the micro- and meso- structure of the tape before and after heating. The experiments resulted in significant changes in the tape structure, namely increased out-of-plane deformation, waviness, arc-length width, roughness, thickness and volumetric void content. This study shows for the first time that a unique deconsolidation behavior takes place during the heating phase of LAFP: the deconsolidation mechanisms are exacerbated by the non-uniform temperature at the tape surface, which is caused by roughness increase and waviness formation.