Defect layer method to capture effect of gaps and overlaps in variable stiffness laminates made by Automated Fiber Placement

Fayazbakhsh, Kazem; Nik, Mahdi Arian; Pasini, Damiano; Lessard, Larry

doi:10.1016/j.compstruct.2012.10.031

Cited by 130 publications

(89 citation statements)

References 11 publications

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“…Models with different sizes and distributions of gaps and overlaps were set up in order to study how these singularities affect properties. Numerical studies have also been performed to examine the influence of gap and overlap defects on the in-plane stiffness and buckling of laminates laid up by AFP [23][24][25]. These indicate that overlaps can result in an increase in properties, in contrast to gaps which tend to weaken these materials.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and tensile properties of carbon–epoxy laminates produced by automated fibre placement: Influence of a caul plate on the effects of gap and overlap embedded defects

Lan

Cartié²,

Davies

et al. 2015

Composites Part A: Applied Science and Manufacturing

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a b s t r a c tAutomated fibre placement (AFP) enables the trajectory of unidirectional composite tape to be optimized, but laying down complex shapes with this technology can result in the introduction of defects. The aim of this experimental study is to investigate the influence of gaps and overlaps on the microstructure and tensile properties of carbon-epoxy laminates. First, a comparison between a hand-layup and AFP layup, draped and cured under the same conditions, shows equivalent microstructures and tensile properties. This provides the reference values for the study. Then, gap and overlap embedded defects (more or less severe) are introduced during manufacturing, on two cross-ply layups [(0°/(90°)5/0°] and [(90°/0°)2/90°]. Autoclave cure without a caul plate results in local thickness variation and microstructural changes which depend on the defect type. This has a strong influence on mechanical performance. Use of a caul plate avoids these variations and in this case embedded defects hardly affect tensile properties.

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Section: Introductionmentioning

confidence: 99%

Microstructure and tensile properties of carbon–epoxy laminates produced by automated fibre placement: Influence of a caul plate on the effects of gap and overlap embedded defects

Lan

Cartié²,

Davies

et al. 2015

Composites Part A: Applied Science and Manufacturing

View full text Add to dashboard Cite

show abstract

“…Their models consider the effect of inplane ply waviness and the variable ply layups at gaps and overlaps. In a similar way, Fayazbakhsh et al [9,10] investigated the influence of in-plane ply waviness and variable stiffness induced by triangular gaps and overlaps at tow-drop areas on the buckling load. Both Lopes et al's and Fayazbakhsh et al's models ignored the out-of-plane waviness caused by gaps and overlaps.…”

Section: Introductionmentioning

confidence: 99%

“…The inhomogeneity can be effectively modelled by considering the in situ ply layup information at gaps and overlaps [3,[6][7][8][9][10]; however, there is a lack of effective way to include the out-of-plane waviness by various combinations of gaps and overlaps. A ply-by-ply modelling technique with intra-ply cohesive elements for splits and inter-ply cohesive elements for delamination has been developed in the University of Bristol [12] and successfully applied to modelling the open-hole tension [13] and over-height compact tension tests [14].…”

Section: Introductionmentioning

confidence: 99%

Modelling the effect of gaps and overlaps in automated fibre placement (AFP)-manufactured laminates

Hallett

Wisnom

2015

Science and Engineering of Composite Materials

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Abstract:In automated fibre placement (AFP) process, gaps and overlaps parallel to the fibre direction can be introduced between the adjoining tapes. These gaps and overlaps can cause a reduction in strength compared with pristine conditions. Finite element modelling is an effective way to understand how the size and distribution of such gaps and overlaps influences the strength and failure development. Many modelling work showed that out-ofplane waviness and ply thickness variations caused by gaps and overlaps play an important role in inducing the strength knock-down; however, there has been a lack of effective way to explicitly model the ply waviness, which constrained the relevant research. In this work, 3D meshing tools were developed to automatically generate ply-byply models with gaps and overlaps. Intra-ply and inter-ply cohesive elements are also automatically inserted in the model to capture the influence of splitting and delamination. Out-of-plane waviness and ply thickness variations caused by gaps and overlaps are automatically modelled. Models with various sizes and distribution of gaps and overlaps were built to predict the reduction of strength as a function of the magnitude and type of the defects. Results of gap and overlap models will be used to guide future experimental characterization of simulated AFP process defects, manufactured by hand layup from prepreg tape.

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“…For instance, the relative strength reduces to 10 % of its optimum of the angle extends to about 60 degrees. The authors of Fayazbakhsh et al 3 and Croft et al 4 confirm that gaps reduce the strength and the stiffness of the laminate. Thus, overlaps can locally increase the strength in contrast to accurate laminates.…”

Section: Introduction To Smart Fiber Placementmentioning

confidence: 89%

Static and quasi-static behavior of an adaptive system to compensate path errors for smart fiber placement

et al. 2015

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Smart fiber placement is an ambitious topic in current research for automated manufacturing of large-scale composite structures, e.g. wing covers. Adaptive systems get in focus to obtain a high degree of observability and controllability of the manufacturing process. In particular, vibrational issues and material failure have to be studied to significantly increase the production rate with no loss in accuracy of the fiber layup. As one contribution, an adaptive system has been developed to be integrated into the fiber placement head. It decouples the compaction roller from disturbances caused by misalignments, varying components' behavior over a large work area and acceleration changes during operation. Therefore, the smart system axially adapts the position of the compaction roller in case of disturbances. This paper investigates the behavior of the system to compensate quasi-static deviations from the desired path. In particular, the compensation efficiency of a constant offset, a linear drift with constant gradient and a single-curved drift is studied. Thus, the test bed with measurement devices and scenarios is explained. Based on the knowledge obtained by the experimental data, the paper concludes with a discussion of the proposed approach for its use under operating conditions and further implementation.

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Defect layer method to capture effect of gaps and overlaps in variable stiffness laminates made by Automated Fiber Placement

Cited by 130 publications

References 11 publications

Microstructure and tensile properties of carbon–epoxy laminates produced by automated fibre placement: Influence of a caul plate on the effects of gap and overlap embedded defects

Microstructure and tensile properties of carbon–epoxy laminates produced by automated fibre placement: Influence of a caul plate on the effects of gap and overlap embedded defects

Modelling the effect of gaps and overlaps in automated fibre placement (AFP)-manufactured laminates

Static and quasi-static behavior of an adaptive system to compensate path errors for smart fiber placement

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