Far-field and near-field strain response of Automated Tow-Placed laminates to stress concentrations

Cairns, Douglas S.; Ilcewicz, Larry B.; Walker, T. H.

doi:10.1016/0961-9526(93)90023-d

Cited by 14 publications

(5 citation statements)

References 2 publications

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“…Following the layup, the manufactured part is placed in an autoclave to consolidate the laminate plies, polymerizing the resin contained in the prepreg tapes. Mechanical tests on specimens from laminated AFP components have highlighted an increase in buckling load [6,7], reduced effects of stress concentrations [8,9] and reduced notch sensitivity [10].…”

Section: Introductionmentioning

confidence: 98%

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: 98%

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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“…Researchers have used various finite element methods to understand failure mechanisms caused by gaps and overlaps in composites. Cairns et al [5] used local inhomogeneity models with double stiffness for overlap regions and resin properties for gaps to study the influence of defects on the tensile failure. They found that the subcritical damage like splits and delamination played a greater role than the inhomogeneity in its influence on the failure.…”

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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“…Sawicki and Minguett [48], Cairns et al [104] already investigated the mechanical consequences of gaps and overlaps in the 1990s using FE analyses of 2D laminate models. However, their modelling approaches differ fundamentally.…”

Section: Modelling Analysis and Evaluation Of Afp Structures With Gamentioning

confidence: 99%

“…However, their modelling approaches differ fundamentally. Cairns et al [104] map gaps and overlaps simplified by adapting the elastic properties locally. Sawicki and Minguett [48] pursue a detailed modelling strategy for gaps and overlaps, based on their experimental findings (cf.…”

Section: Modelling Analysis and Evaluation Of Afp Structures With Gamentioning

confidence: 99%

Manufacturing-Induced Imperfections in Composite Parts Manufactured via Automated Fiber Placement

2019

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The automated fiber placement process (AFP) enables the manufacturing of large and geometrical complex fiber composite structures with high quality at low cycle times. Although the AFP process is highly accurate and reproducible, manufacturing induced imperfections in the produced composite structure occur. This review summarizes and classifies typical AFP-related manufacturing defects. Several methodologies for evaluating the effects of such manufacturing defects from the literature are reviewed. This review paper presents recent scientific contributions and discusses proposed experimental and simulation-based methodologies. Among the identified ten defect classes, gaps and overlaps are predominant. This paper focuses then on methods for modelling and assessing gaps and overlaps. The state of the art in modelling gaps and overlaps and assessing their influence on mechanical properties is presented. Finally, research gaps and remaining issues are identified.

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Far-field and near-field strain response of Automated Tow-Placed laminates to stress concentrations

Cited by 14 publications

References 2 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

Manufacturing-Induced Imperfections in Composite Parts Manufactured via Automated Fiber Placement

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