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

Li, Xiangqian; Hallett, Stephen R.; Wisnom, Michael R

doi:10.1515/secm-2013-0322

Cited by 94 publications

(51 citation statements)

References 12 publications

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“…A Hi-fidelity Finite Element Method (Hi-FEM) has been developed to predict the Mode I trans-laminar fracture in composite laminates using the explicit FE software LS-Dyna. The Hi-FEM combines the FEM methods from [13,17], with potential delaminations and multiple split paths explicitly modelled using cohesive interface elements, together with an automated meshing technique [28]. Previously, the focus was on delamination dominated failure in QI laminates with blocked plies [17] and the FPZ development including splitting, delamination and local fibre breakage with dispersed plies [13].…”

Section: Virtual Over-height Compact Tension (Oct) Testmentioning

confidence: 99%

Deducing the R-curve for trans-laminar fracture from a virtual Over-height Compact Tension (OCT) test

Wisnom

Hallett³

2019

Composites Part A: Applied Science and Manufacturing

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The R-curve for Mode I trans-laminar fracture energy in quasi-isotropic IM7/8552 carbon/epoxy laminates is here deduced numerically from a virtual Over-height Compact Tension (OCT) test. A High-fidelity Finite Element Method (Hi-FEM) using the explicit Finite Element (FE) software LS-Dyna was adopted. Cohesive interface elements and a Weibull fibre failure criterion were used to predict failure. The input parameters for the Hi-FEM were measured from independent characterisation tests.OCT specimens were tested to verify the Hi-FEM results with good agreement. The Rcurve effect is postulated to be caused by the growth of the height of the Fracture Process Zone (FPZ) with crack length. Hi-FEM can be used to better understand Mode I trans-laminar fracture toughness tests and generate fracture properties such as damage heights and R-curves for future structural scale models.

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Section: Virtual Over-height Compact Tension (Oct) Testmentioning

confidence: 99%

Deducing the R-curve for trans-laminar fracture from a virtual Over-height Compact Tension (OCT) test

Wisnom

Hallett³

2019

Composites Part A: Applied Science and Manufacturing

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“…Li et al [22] developed a 3D meshing tool to automatically generate gaps and overlaps numerically. This enabled them to investigate the thickness variations associated with singularities, as well as out-of-plane ply waviness.…”

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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“…This was achieved by deleting a 1 mm strip of interface elements in the numerical models and by inserting a starter crack in the experimental specimens using release film. Other defect types were outside of the scope of this piece of work, but such high-fidelity modelling techniques are the subject of ongoing work at the University of Bristol (Mukhopadhyay et al, 2013;Li et al, 2013). Further investigation of potential manufacturing defects in tidal turbine blade structures and their effects on damage progression and failure will be important in future studies.…”

Section: Single Cover Ply Resultsmentioning

confidence: 99%

Advanced numerical modelling techniques for the structural design of composite tidal turbine blades

Harper

Hallett

2015

Ocean Engineering

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Abstract:Tidal Stream turbine blades must withstand both extreme one-off loads and severe fatigue loads during their 20-25 year required lifetimes in harsh marine environments. This necessitates the use of high-strength fibre reinforced composite materials to provide the required stiffness, strength and fatigue life, as well as resistance to corrosion, whilst minimising the mass of material required for blade construction and allowing its geometric form to provide the required hydrodynamic performance. Although composites provide superior performance to metals, potential failure mechanisms are more complicated and difficult to predict. A dominant failure mechanism is interfacial failure (delamination) between the composite layers (plies). This paper demonstrates how the development of numerical techniques for modelling the growth of interfacial cracks can aid the design process, allowing the effects on crack growth from potential manufacturing defects and the effect of stacking sequence of composite plies to be analysed. This can ultimately lead to reduced design safety margins and a reduction in the mass of material required for blade manufacture, essential for reducing lifecycle costs. Although the examples provided in this article are specific to tidal turbine blades, the analysis techniques are applicable to all composite structures where fatigue delamination is a primary failure concern.

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

Cited by 94 publications

References 12 publications

Deducing the R-curve for trans-laminar fracture from a virtual Over-height Compact Tension (OCT) test

Deducing the R-curve for trans-laminar fracture from a virtual Over-height Compact Tension (OCT) test

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

Advanced numerical modelling techniques for the structural design of composite tidal turbine blades

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