Gap filling mechanisms during the thin ply Automated Tape Placement process

Automated Tape Placement (ATP) is one of the attractive automated composite manufacturing processes as it reduces labor cost, increases production rate and improves repeatability. In this method, the part is built by consolidating one unidirectional prepreg tape layer at a time with a placement head using a compaction roller. Defects such as gaps between neighboring tapes during lay up are inevitable. This challenge becomes even more critical in the ATP of the thin ply prepreg tapes as the ratio of the gap width to the tape thickness increases. The filling process of such gaps during the process cycle results in resin-rich areas and fiber waviness. In this paper, we present a model to numerically simulate the gap-filling process by coupling the squeeze flow behavior within the tapes to fill the gap with the deformation of the top layers into the hollow space within the gap. First, the experimental results clarify the microstructural physics of the gap-filling process. This is followed by proposing a model to predict the flow front of resin that moves to fill the gap and the gap thickness. The predictions of the model are compared with experimental results and validated by the micrographs of fabricated samples.