Colloquium: Seyfi Taskin (ASM)

This thesis investigates the mitigation of in-plane fiber waviness in the press consolidation of Carbon Fiber Polyetherketoneketone (PEKK) V-tail front spars. The manufacturing process includes Automated Tape Laying (ATL), preforming, and press consolidation. The study identifies that fiber waviness originates during the press consolidation phase, particularly on the outer mold line (OML) side. Three hypotheses are tested: waviness due to male tool tilt, flange compression, and tool-part interaction during tool expansion. Mitigation strategies include installing guidance pins, modifying the pressurization sequence, central fixation of the female tool, and spot welding the ATL stack. These actions successfully eliminated fiber waviness, as confirmed by subsequent consolidations. An image processing algorithm was also developed for consistent measurement. The study concludes that uniform compaction, central tool fixation, and maintaining a consistent temperature range are essential to preventing fiber waviness in composite spar manufacturing.

Supervisor: Dr. Baris Caglar