Characterizing reflectance patterns of UD CF/PAEK composites for laser assisted fibre placement

In-situ consolidation during laser assisted fibre placement (LAFP) has the potential to provide a fast and cost-effective manufacturing solution, that can be used for manufacturing large scale aerospace components. The processing temperature plays a vital role in obtaining consistent consolidation quality and interlaminar bond strength when manufacturing parts with in-situ consolidation. The heat flux distribution may be influenced by the reflection patterns of a composite surface, and therefore accurate descriptions of these patterns are important to obtain a good prediction of the thermal response during processing. The present study proposes a fast methodology to characterize the reflective patterns of a composite surface subjected to near-infrared laser light under a shallow incidence angle, using a technique based on high dynamic range imaging. It is observed that, in line with other studies, the reflection pattern of a CF/LM-PAEK composite tape changes considerably with fibre orientation. Moreover, the radiance maps of the reflected patterns showed a 15% decrease in the light received on the screen for a composite under 45° fibre orientation in comparison to same light shone on a sample with 0° fibre orientation.