Optimisation of intra-ply stitch removal for improved formability of biaxial non-crimp fabrics

Chen, S.; Joesbury, Adam M.; Yu, F. Richard; Harper, L.T.; Warrior, N.A.

doi:10.1016/j.compositesb.2021.109464

Cited by 10 publications

(2 citation statements)

References 29 publications

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“…In the case of the hemisphere, the final formed shape was used to show how the fabric compensates for the excess length caused by the 3D geometry. This was the case for example, in Chen et al's study (Chen et al, 2021) into the effect of NCF stitching on asymmetry of the resultant preform. Through the removal of the stitching from a biaxial NCF sample, it was shown wrinkling in the preform is successfully decreased.…”

Section: Introductionmentioning

confidence: 94%

Influence of NCF architecture on the morphology of forming induced wrinkling

Martin

Maes²,

McMahon³

et al. 2023

Front. Mater.

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Biaxial Non-Crimp Fabrics (NCFs) offer the high deposition rates needed to meet the increased production rate targets of the aerospace industry, but formability remains an issue for complex parts. In this study a large scale, complex geometry with a span of 2 m is used to study wrinkle patterns in NCF preforms and how they are influenced by several key NCF parameters. Wrinkle dimensions are captured in 3D scans and used as a proxy metric for “formability”. Results show that whereas location and shape of the wrinkling are driven by geometry, wrinkle size and its metrics (amplitude, wavelength, aspect ratio) are driven by the NCF architecture. In addition, conflicting trends on wrinkle size observed show the complexity of forming as a process. The results presented show the importance of using several characterisation methods and not reducing wrinkling characterisation to a single data point or set.

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Section: Introductionmentioning

confidence: 94%

Influence of NCF architecture on the morphology of forming induced wrinkling

Martin

Maes²,

McMahon³

et al. 2023

Front. Mater.

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“…When forming a stack of plies at different orientations over a double curvature tool, interactions between individual plies were shown to play an important role in the formation of wrinkles [3]. In addition, the occurrence of wrinkles is related to the fabric architecture at mesoscale, for instance the non-crimp fabric (NCF) with pillar stitch pattern [4].…”

Section: Introductionmentioning

confidence: 99%

The prediction of wrinkle formation in multi-layered biaxial fabrics during press tool forming

Yu¹,

Chen²,

Chen³

2023

Third International Conference on Artificial Intelligence and Computer Engineering (ICAICE 2022)

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Liquid composite moulding (LCM) processes are more cost-effective compared to autoclave-cured prepreg, but an independent preforming step is typically required to convert 2D fabric blanks into complex 3D shapes prior to moulding. Numerical models are therefore important to predict the formation of defects during the design phase, in order to ensure the quality of final composite components. A macroscopic finite element model was employed to predict the forming behaviour of multi-layered biaxial non-crimp fabrics (NCF) during the press tool forming using a hemispherical punch. The forming behaviour of the NCF was predicted by simulations considering the bending stiffness of the NCF, enabling fabric wrinkling to be simulated. Simulation results indicate a correlation between fabric wrinkling and the in-plane shear deformation of fabrics. The severity of wrinkles was also influenced by the layup sequence. Compared with the singleorientation layups, more wrinkles were predicted for the layup comprising plies stacked at different orientations due to the dissimilar shear deformation between these plies.

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Characterising the shear resistance of a unidirectional non-crimp glass fabric using modified picture frame and uniaxial bias extension test methods

Kahavita

McCarthy

Zhang³

et al. 2023

Int J Mater Form

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The forming behaviour of a unidirectional non-crimp fabric (UD-NCF) consisting of polyamide stitches with a tricot-chain stitching pattern is explored. Notably, there are no stabilising tows orientated transverse to the main tow direction in this fabric, a common feature in many ‘quasi’ UD-NCFs, this allows extension of the stitch in the transverse direction under certain loading conditions. The lack of stabilising tows introduces a possible low-energy deformation mode to the UD-NCF, which is absent in biaxial fabrics and to a large extent in ‘quasi’ UD-NCFs. The in-plane shear behaviour is initially investigated using both standard ‘tightly-clamped’ picture frame tests and uniaxial bias extension tests. Preliminary results show a dramatic difference in results produced by the two test methods. During the picture frame test, fibres can be subjected to unintended tension due to sample misalignment in the picture frame rig. To mitigate error arising from this effect, the picture frame test procedure is modified in two different ways: by using an intentional pre-displacement of the picture frame rig, and by changing the clamping condition of test specimen. Results show that the modified picture frame test data contain less error than the standard ‘tightly-clamped’ test but also that the shear stiffness of the UD-NCF is notably lower when measured in the bias extension test compared to the picture frame test, mainly due to the difference in loading conditions imposed during the two tests.

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Optimisation of intra-ply stitch removal for improved formability of biaxial non-crimp fabrics

Cited by 10 publications

References 29 publications

Influence of NCF architecture on the morphology of forming induced wrinkling

Influence of NCF architecture on the morphology of forming induced wrinkling

The prediction of wrinkle formation in multi-layered biaxial fabrics during press tool forming

Characterising the shear resistance of a unidirectional non-crimp glass fabric using modified picture frame and uniaxial bias extension test methods

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