Today's KNOWLEDGE Share::Repairs for thermoplastic composite aerostructures!

Today's KNOWLEDGE Share

Developing repairs for thermoplastic composite aerostructures!

The HyPatchRepair project (2019-2022) was funded by the #German government, as part of the LuFo-V3 #aerospace research program, to demonstrate rivet-free repair technology for continuous #fiberreinforced TPC parts. The goal was a set of automated repair techniques to restore the original load-carrying capacity, geometry and aerodynamic surface without adding weight for parts such as #fuselageskins, #wings, #winglets and empennage components, including rudders. These techniques would prepare the repair area, fabricate a load-optimized repair patch and then integrate the patch into the repair area using proven and cost-effective technologies.

The German HyPatchRepair consortium was led by research institutes Faserinstitut Bremen and Laser Zentrum Hannover. The project included Airbus Operations, #aircraftrepair services provider Lufthansa Technik , small aircraft manufacturer Silence Aircraft and optical measurement systems supplier Vereinigte Elektronikwerkstätten as associated partners. Due to its expertise in large TPC structures, #GKN Fokker provided defect/damage cases and helped to define demonstrators.

The process chain conceived by this consortium includes:

Detect damage: An optical measuring system inspects the part to be repaired and determines the area and depth of material that needs to be removed, minimizing this if possible. VEW demonstrated this step using an optical measuring system at its facilities.

Mill the repair area: Damaged material is removed with a DMG MORI five-axis ULTRASONIC mobileBLOCK robot, providing consistent quality, dimensional accuracy and repeatability. To replace the removed plies with an accurate repair patch, the repair area is machined into steps. FIBRE demonstrated this process using the DMG MORI robot while LZH explored using lasers.

Measure the repair area: The stepped repair area must be accurately measured to fabricate a precisely fitting repair patch. LZH demonstrated this step using a Wenglor MLWL 232 laser profile scanner. LabVIEW #software was used to convert the data into the required patch dimensions.

Fabricate repair patches: #Repair patch preforms are fabricated using tailored fiber placement (TFP) and continuous fiber 3D printing and are then consolidated. FIBRE demonstrated the manufacturing of TPC preforms and consolidation using a heated press and specially designed tooling.

Trim patches: The #patches are measured after consolidation and compared with the stepped repair surface. Required trimming is completed using a laser, demonstrated by LZH.

Weld patches: Patches are fused to the repair area using laser beam welding. LZH demonstrated how this method would work while #FIBRE demonstrated the concept using pressure welding in a heated press.

Source; #managingcomposites

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