ISBN 9783843953351

978-3-8439-5335-1, Reihe Luftfahrt

Felipe Alberto Finkenwerder
Verification of the static friction behavior of continuous fiber tapes for processing non-geodesic trajectories by ring filament winding

187 Seiten, Dissertation Universität Stuttgart (2022), Hardcover, A5

Zusammenfassung / Abstract

Continuous carbon fiber reinforced plastics (CFRP) is a key material for creating lightweight and energy-efficient aircraft frames. However, the current lack of machine configurations capable of conformably orienting and fixing the position of continuous fiber tows according to expected load directions hinder productivity, viability, and weight-specific mechanical properties for airframe applications. Advancements in ring filament winding (RFW) technology based on dry processing continuous tapes are capable of solving these constraints, optionally orienting and fixing continuous fiber tows as unidirectional patterns by relying solely on geometric and frictional tow conditions. This research therefore investigates decisive frictional conditions for designing and processing non-geodesic filament wound trajectories, using dry thermoplastic veil binder coated carbon fiber tapes (CFts). To validate the realistic frictional behavior of CFt’s whilst their processing, a theoretical experimental approach is conducted. Initially, a analytical model predicts frictional forces along non-geodesics paths, between shearing CFt surfaces with a veil binder interleaf. Then, to confirm the realistic application of non-geodesic paths, frictional forces at tribometry test are determined and compared with those measured along filament wound non-geodesic paths under similar local conditions. Plate-plate tribometry experiments reveal the correlation of normal load, fiber contact angle, and static friction force, highlighting the impact of interply filament drapability on the frictional behavior. A novel friction measurement method along winding paths proves similar friction levels during the RFW process, assisting the reliable prediction of friction forces. Finally, thermal conditioning tests on RFW preforms indicate the impact of heating dwell times and the binder distribution on the resulting mechanical properties of CFRP laminates, indicating best conditions for their manufacturing.