Formability evaluation of carbon fiber NCF by a non-contact 3D strain measurement system and the effects of blank folder force on its formability

Abstract

Non-Crimp Fabric (NCF) consists of unidirectional plies, which are kept together by stitching yarns arranged in a number of different orientations relative to the fabric production direction. Since NCF has no crimp, NCF can take full advantage of the continuous carbon fibers.As NCF is deformed mainly due to shear deformation, it is difficult to form 3D shapes from it. Therefore, formability improvement of NCF by slitting a textile preform has been attempted; however, problems such as strength degradation at a notch and cost increase due to the increase of working process have occurred. So, it is necessary to improve formability of NCF without slitting. One of the methods of formability improvement is to use blank holder force. In previous studies, though the influence of blank holder force on formability of woven fabrics has been clarified, that on formability of NCF is uncertain.In this study, the hemisphere geometry punch drape test was conducted to evaluate the influence of blank holder force on the formability of NCF. Meanwhile, deformation of NCF during the drape test was measured by a non-contact 3D strain measurement system.

Defect formation during preforming of a bi-axial non-crimp fabric with a pillar stitch pattern

“…Non-Crimp Fabrics (NCF) offer increased stiffness and strength over frequently used woven fibre architectures [1] as reinforcement in composite structures, but have been shown to be more difficult to form into 3D shapes [2]. Bi-axial NCFs are composed of two layers of aligned yarns, typically at 0°/90°or ±45°, which are bonded together by through-thickness stitches.…”

The Role of Bias Extension Testing to Guide Forming of Non-Crimp Fabrics

“…Formability of fabrics over 3D complex shapes has been extensively covered in the literature (Hancock and Potter, 2006;Tanaka et al, 2014;Chen et al, 2017). However the quest to use formability as a quantitative property and metric to aid material selection still remains.…”

Large Scale Forming of Non-Crimp Fabrics for Aerostructures

“…A review of the literature reveals the additional challenges with forming of NCFs by comparison to their woven counterparts [20]. Viisainen et al attributes the variability in NCF preform results to the more 'complex architecture' [18], with NCFs consisting of intra-ply stitches rather than interlaced primary yarns.…”