[home] [Personal Program] [Help]

---

Session: Session 2: Trajectories for Automated Fiber Placement
Session starts: Tuesday 14 April, 11:00
Presentation starts: 11:20
Room: Main

---

Lukas Raps (German Aerospace Center (DLR) - Institute of Structures and Design)
Ashley Chadwick (German Aerospace Center (DLR) - Institute of Structures and Design)
Heinz Voggenreiter (German Aerospace Center (DLR) - Institute of Structures and Design)

Abstract:
With meticulous process control and the correct manufacturing parameters, autoclave-level mechanical properties have been proven to be achievable using in-situ Automated Fiber Placement (AFP). This long-awaited result at the coupon level has spurred the use of AFP for larger structural components for structures. However, the complex geometries, particularly double curvatures required for real part geometries, present additional obstacles to the already challenging process. Without post-consolidation in a hot press or autoclave, the severity of geometry-related deviations from the ideal ply composition, namely fiber angle defects or tow-drops, remains unquantified. This work presents a systematic derivation of layup deviations which inevitably arise for tape placement on complex geometries. Ply layup simulation software and analytical Python scripts are used and the triangular correlation between the three deviation types (steering defects, gaps/overlaps and angle deviation) is demonstrated. Layup strategies are developed specifically for the characteristics of the in-situ AFP process. Three complex example geometries are investigated as case studies: A Variable Stiffness Panel (VSP), a spherical hydrogen tank structure and a complex double-curved fuselage section. A spherical hydrogen tank section is manufactured as a validation experiment (Figure 1). The results of this study show that increasing the number of parallel tows generally elevates angle deviation and critical steering radii while reducing area related coverage defects; an optimal design can therefore be pursued by maximizing parallel tows within process dependent limits (e.g., ±3° angle deviation for thermoset AFP). Simulation reveals that steering radii can drop to as low as 100 mm for spherical domes and 500 mm for the investigated fuselage sections, with gaps and overlaps varying from 100 mm to several meters depending on geometry and layup. This work presents detailed correlations between layup strategy parameters and the resulting layup deviations, providing algorithms for optimized layup strategies for in-situ AFP on complex geometries.