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Session: Session 9: Modelling and Characterisation of AFP
Session starts: Thursday 16 April, 10:50
Presentation starts: 10:50
Room: Main

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Willian dos Santos Pinto (ONERA)
Juan Manuel Garcia (ONERA)
Christian Fagiano (ONERA)
Cédric Huchette (ONERA)
Alain Rassineux (Laboratoire Roberval, UTC)

Abstract:
Automated fiber placement (AFP) is a manufacturing process widely employed on aeronautical sector. This process involves a robotic arm that lays down pre-impregnated tows, thereby enhancing automation, accuracy and repeatability in manufacturing of composite parts. In addition, AFP allows a bigger possibility of design, including components with non-conventional placement path. Nevertheless, despite these advantages, two types of singularities are inherently generated during the AFP manufacturing process: gaps and overlaps. These singularities must be considered on the part design since they impact the mechanical performance of the final product. Consequently, modeling strategies to predict the behavior of structures with the presence of singularities is needed in order to optimize the AFP part design. This work aims to develop a strategy to mesh the AFP composite parts based on the placement path. The mesh method, called Generative Geometric Approach, uses the coordinates of robot trajectory to reconstruct the AFP structure mesh resulting in a structured and conformal mesh. Some geometric aspects intrinsically emerge from this method, such as ply waviness, void regions and local thickness variation. This method, which is purely based on the geometric path, leads to discrepancies between the mesh geometry and the final AFP part, as thermo-mechanical effects are not considered. Therefore, a geometric validation is carried out on the model by comparing it with imaging technique observations. This comparison reveals whether the model over- or underestimate ply waviness and/or local thickness variation, allowing the model to be adapted to best represent the AFP composite geometry. Conversely, finite‑element analysis highlights how the geometry influences the kinematic response induced by ply waviness and local thickness variations, emphasizing the need to use an accurate geometric model to obtain a representative mechanical behavior.