Modelling approach for the prediction of stitch influence during woven fabric draping

Duhovic, Miro; Mitscháng, Peter; Bhattacharyya, Debes

doi:10.1016/j.compositesa.2011.03.025

Cited by 32 publications

(16 citation statements)

References 40 publications

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“…It was concluded that it is possible to transfer shear forces into un-sheared regions of the ply during forming. Through-thickness stitching in multi-ply preforms has been simulated in explicit finite element analyses using spot weld constraints [3,10]. Whilst only multi-ply stacks with identical ply orientations were studied, for certain cases, redistribution of strains within the fabric through use of stitches was proven feasible to avoid wrinkling.…”

Section: Introductionmentioning

confidence: 99%

“…Fixation of the fibrous structure through application of through-thickness stitch-bonds reduces in-mould assembly time and can aid robotic placement by enabling multi-layer stacks to be processed as one single preform. Previous research on reinforcement forming has generally addressed the simulation of components consisting of a single fabric ply [1,2], or preforms of multiple plies with identical orientation [3,4], where the difference in draw-in between plies and inter-ply friction is not as significant as in heterogeneous multi-ply preforms [5,6]. However, little work has been reported on forming of complex stacking patterns or multi-ply preforms containing localised stitch-bonds.…”

Section: Introductionmentioning

confidence: 99%

“…Investigations into the influence of stitches have been generally limited to studying intraply stitches in NCFs [9] or single woven plies [3], to understand how they can be used to control local yarn angles. Molnar et al [4] investigated the influence of inter-ply stitching experimentally.…”

Section: Introductionmentioning

confidence: 99%

“…These parameters can be obtained from material testing [3]. Values of ݇ ௧ ௦௧ = 32.55 kN/m and ∆݈ = 0.57 mm [3] have been used throughout this study.…”

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confidence: 99%

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Inter-ply stitching optimisation of highly drapeable multi-ply preforms

Chen

Endruweit

Harper

et al. 2015

Composites Part A: Applied Science and Manufacturing

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An efficient finite element model has been developed in Abaqus/Explicit to solve highly nonlinear fabric forming problems, using a non-orthogonal constitutive relation and membrane elements to model bi-axial fabrics. 1D cable-spring elements have been defined to model localised inter-ply stitch-bonds, introduced to facilitate automated handling of multi-ply preforms. Forming simulation results indicate that stitch placement cannot be optimised intuitively to avoid forming defects. A genetic algorithm has been developed to optimise the stitch pattern, minimising shear deformation in multi-ply stitched preforms. The quality of the shear angle distribution has been assessed using a maximum value criterion (MAXVC) and a Weibull distribution quantile criterion (WBLQC). Both criteria are suitable for local stitch optimisation, producing acceptable solutions towards the global optimum. The convergence rate is higher for MAXVC, while WBLQC is more effective for finding a solution closer to the global optimum. The derived solutions show that optimised patterns of through-thickness stitches can improve the formability of multi-ply preforms compared with an unstitched reference case, as strain re-distribution homogenises the shear angles in each ply.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…These parameters can be obtained from material testing [3]. Values of ݇ ௧ ௦௧ = 32.55 kN/m and ∆݈ = 0.57 mm [3] have been used throughout this study.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Inter-ply stitching optimisation of highly drapeable multi-ply preforms

Chen

Endruweit

Harper

et al. 2015

Composites Part A: Applied Science and Manufacturing

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“…Simulation tools, supported by experimental investigations of textiles or heated organo sheet in shear frames ("picture frame test"), can help to identify areas critical for wrinkle formation in complex shaped parts [42]. These shear experiments can be used in order to define the shear locking angle for a given material.…”

Section: Thermoplastic Composite Technologymentioning

confidence: 99%

Manufacturing Technology

Breuer¹

2016

Commercial Aircraft Composite Technology

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The selection of the manufacturing technology will inevitably influence cycle times and manufacturing cost, i.e. non-recurring cost as well as recurring cost. It will also influence quality assurance and assembly effort. Due to the strong link of advanced design schemes and suitable manufacturing technology, maintenance cost (for example with respect to the accessibility of integrated CFRP-structures) are also affected. Different manufacturing technologies require different semifinished materials with different mechanical properties. Hence, the selection of the manufacturing technology will also influence part weight and operational cost. In this chapter, all state of the art as well as newly developed manufacturing technologies and recent R&D are described; advantages and shortfalls are highlighted. Automated tape laying, fibre placement and pultrusion technology are explained, and examples are provided. The autoclave process technology is discussed, including unwanted defects in the cured material and the description of quality assurance technologies (dielectric analysis and non-destructive testing by ultrasound). Different textile infusion technologies are characterised. Thermoplastic stamp forming technology and thermoplastic tape laying technology are discussed in detail. The description of the filament winding technology is followed by the presentation of joining and bonding technologies. Riveting as well as adhesive bonding and welding processes are discussed. The chapter closes with the description of a possible method for the selection of "the right process technology for the right part". Keywords Prepreg Autoclave TechnologyThe majority of composite airframe parts are made from prepregs by means of the autoclave technology. First, prepregs are taken out of the storage, i.e. a freezer with a temperature of À18 C. In the second step, they are warmed up to room temperature and unpacked. Afterwards they are cut into shape, positioned in the desired lay up on a tool, vacuum bagged, evacuated, and exposed to temperature and pressure in autoclaves until the resin has cured. After cooling, the parts are unpacked, contour milled and quality checked.During the last 20 years, manual prepreg cutting and placement processes have been more and more replaced by automatic processes; however, there is still a lot of manual work especially for bagging and debagging of parts. The cutting process is shown in Fig. 4.1.The prepreg coils are stored in paternoster systems with computer supported monitoring of material types and their shelf life. Prepregs are positioned on a carrier and automatically cut into pieces by a static or an oscillating knife, which is guided on a portal and can move in x/y direction. Several thousands of individual patterns can be necessary for the different airframe parts.The processing area is typically wide enough for prepreg coils of 1.8 m width, the length of the cutting table can be 30 m or more. Several layers placed on top of each other can be cut at once on a cutting table. Alternat...

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