Waviness and fiber volume content analysis in continuous carbon fiber reinforced plastics made by tailored fiber placement

Abstract

In this paper, the influence of Tailored Fiber Placement (TFP) processing-related parameters on in-plane waviness and fiber volume content of unidirectional carbon fiber reinforced plastic (UD-CFRP) composites is experimentally investigated. Twelve UD-CFRP laminates, whose preforms are produced via TFP, are manufactured by considering different values of stitch width, stitch distance and stitch sequence as well as two different stitching yarn types by resin transfer molding (RTM). The investigated TFP parameters are representative of the producing capability of a typical TFP machine. Based on calibrated high-resolution photographic images and manual recognition of the roving orientation on the laminate surface, the in-plane waviness is qualitatively and quantitatively measured using Fourier analysis. With this approach, the dominant waviness, in-plane wavelengths, and amplitudes of different stitching parameters can be evaluated. Both mean fiber volume content within the roving and within the TFP layer are determined through optical micrographs of the produced laminates. Experimental results reveal that the resulting waviness and the fiber volume content in the roving and within the TFP layer strongly dependent on TFP process parameters. In particular, the stitch width plays a major role on both fiber volume contents, whereas the stitch distance is less relevant.