Simulations and experiments for automated fiber placement of prepreg slit tape: Wrinkle formation and fundamental observations

Abstract

Simulations and experiments for automated fiber placement (AFP) of prepreg slit tape (tow) on a flat surface with different radii of curvature are presented, with emphasis on characterization of wrinkle formation. Bonding of the slit tape to the substrate surface is modelled through a sticky contact definition in Abaqus. Subsequent delamination and wrinkling are predicted through incorporation of measured mixed mode cohesive TSL for contact and bonding of the slit tape and substrate. Comparisons of predicted wrinkle shape, amplitude and wavelength to experimental measurements show excellent agreement for a 6.35 mm wide IM7/8552-1 prepreg tow placed on a flat surface using four different radii of curvature. In addition, simulations are demonstrated to be capable of capturing the mechanisms of wrinkle formation using a generally accepted damage model. Careful inspection of the stress and deformation conditions at the tow-substrate interface under the compaction roller reveals a combination of Mode II and Mode III tractions, with significant damage predicted under the roller due to the Mixed Mode II/III traction conditions. After passage of the roller, nearly instantaneous initiation and growth of wrinkles occur with relatively consistent spacing under predominantly Mode I condition at the interface.