HLFC-WIN: Suction Rib Infusion The Digital Infusion Center in Action

Abstract

Suction Rib Infusion The Digital Infusion Center in Action Successful composite manufacturing -especially in case of LRI (Liquid Resin Infusion) processes- heavily depends on choosing the correct time, temperature and pressure parameters. To reproduce and further optimize parameter settings the Bolle & Cords company together with DLR developed a mobile and versatile infusion/injection device that has both a fully automatic and a fully manual operating mode with advanced monitoring options. Beside its dual container operation option, the so-called Digital Infusion Center features a highly responsive microwave heating system and very accurate internal sensors to analyse the actual status of the infusion process. The major development goal however was to integrate injection machine internal sensors and also tooling and process environment (oven, autoclave, press) mounted sensors in order to counteract unexpected process deviations. In the context of the Clean Sky 2 project HLFC-Win the Digital Infusion Center has been used in an OOA (Out Of Autoclave) process for the very first manufacturing trial of the geometrically complex “Suction Rib” structure. The “Suction Rib” is a new, very compact approach for HLFC (Hybrid Laminar Flow Control) wings where compressor and suction system are directly integrated in the wing rib structure. Right from the start of the infusion there was a significant deviation between the Polyworx simulation and the experiment due to partially blocked resin transfer lines. After one hour of automatic infusion with conservative settings an updated simulation with simulated, blocked resin transfer lines clearly showed that the chosen parameters will not lead to a successful infusion and therefore the process has been switched into manual mode. In manual mode it was possible to increase the resin pressure slightly above ambient pressure which then allowed to reduce the blocking and force resin into the vacuum bag. The final result was that the “Suction Rib” was fully infused and that the infusion characteristics of the mould concept were fully understood. For upcoming “Suction Rib” infusions the experiences gained in the first trial can now be applied directly when a similar problem occurs during infusion. In addition, the Digital Infusion Center will automatically detect the problem by analyzing the resin flow and will at least propose a mitigation action (in this case temporary pressure increase over ambient pressure).