In situ observation of defect formation during composite manufacturing
This Advances In Engineering article describes the underlying physical mechanisms for the formation of fiber waviness during flat laminate consolidation.
The study is focused on the production of waviness-free laminates by determining processing guidelines, based on a descriptive model. It is desirable to prevent or minimize fiber waviness, as it causes a knockdown in the mechanical properties of the part. The recently published paper “Real-time observation of waviness formation during C/PEEK consolidation” in Composites Part A: Applied Science and Manufacturing, describes an experimental set-up for the in situ observation of the behavior of a thermoplastic composite ply during melting and consolidation. For C/PEEK unidirectional composites, it was observed that waviness forms during cooling, between the maximum process temperature and the crystallization temperature. The degree of fiber waviness did not change after crystallization. This has lead to the conclusion that tool shrinkage, transferred to the laminate via tool-ply friction, is the driving force for waviness formation during flat laminate consolidation.
