Mode-II fracture behaviour of aerospace-grade carbon fibre/epoxy composites interleaved with thermoplastic veils

Bologna, Francesca; Scarselli, Gianfranco; Ivanković, Alojz

doi:10.1016/j.compscitech.2020.108065

Cited by 47 publications

(25 citation statements)

References 37 publications

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“…[5] In the last two decades, indeed, nonwoven fabrics made of nanofibers gained increasing attention, thanks to their high surface-to-volume ratio and outstanding properties. Besides the application as highly efficient filters, [6,7] nanofibrous nonwoven mats (known as nanomats too) are successfully used in tissue engineering, [8,9] sensors, [10,11] catalysis, [12,13] and composite materials with enhanced mechanical performances [14][15][16][17][18] and/or peculiar properties. [19] In most applications, the assessment of mat mechanical properties is fundamental for evaluating effective applicability, and tensile testing is commonly performed.…”

Section: Introductionmentioning

confidence: 99%

How Nanofibers Carry the Load: Toward a Universal and Reliable Approach for Tensile Testing of Polymeric Nanofibrous Membranes

Maccaferri

Cocchi

Mazzocchetti

et al. 2021

Macro Materials & Eng

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Nanofibrous nonwovens show high versatility and outstanding properties, with reduced weight. Porous morphology, high material flexibility and deformability challenge their mechanical testing, severely affecting results reliability. Still today, a specific technical standard method to carry out tensile testing of nonwoven nanofibrous mats is lacking, as well as studies concerning tensile test data reliability. In this work, an accurate, systematic, and critical study is presented concerning tensile testing of nonwovens, using electrospun Nylon 66 random nanofibrous mats as a case study. Nanofibers diameter and specimen geometry are investigated to thoroughly describe the nanomat tensile behavior, also considering the polymer thermal properties, and the nanofibers crossings number as a function of the nanofibers diameter. Below a threshold value, which lies between 150 and 250 nm, the overall mat mechanical behavior changes from ductile to brittle, showing enhanced elastic modulus for a high number of nanofibers crossings. While specimen geometry does not affect tensile results. Stress–strain data are analyzed using a phenomenological data fitting model to better interpret the tensile behavior. The experimental results demonstrate the high reliability of the proposed mass‐based load normalization, providing a simple, effective, and universally suitable method for obtaining high reproducible tensile stress–strain curves.

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Section: Introductionmentioning

confidence: 99%

How Nanofibers Carry the Load: Toward a Universal and Reliable Approach for Tensile Testing of Polymeric Nanofibrous Membranes

Maccaferri

Cocchi

Mazzocchetti

et al. 2021

Macro Materials & Eng

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“…Mode II (G IIC ) fracture toughness was lower than in similar thermoset composites toughened with thermoplastic veils [ 79 , 88 , 89 , 90 ]. Toughening mechanisms in mode II (G IIC ) were more complex than mode I (G IC ), depending on most on the neat properties of the matrix and the architecture of the reinforcement, rather than the fiber bridging effect.…”

Section: Resultsmentioning

confidence: 97%

“…The PA veil was included in the AIR-3R vitrimer composite in order to enhance the interlaminar toughness and impact resistance, as has been demonstrated in several studies addressing interleaving thermoplastic veils [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 ]. In view of this microstructure, a new batch of tests was performed on samples without the thermoplastic PA veil; i.e., it was removed and all other conditions were maintained.…”

Section: Resultsmentioning

confidence: 99%

Study into the Mechanical Properties of a New Aeronautic-Grade Epoxy-Based Carbon-Fiber-Reinforced Vitrimer

Cárdenas¹,

Gayraud²,

Rodrı́guez³

et al. 2022

Polymers

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The current drive for sustainability demands recyclable matrices for composite materials. Vitrimers combine thermoset properties with reprocessability, but their mechanical performance in highly loaded applications, for instance, composites for aeronautics, is still to be demonstrated. This work presents the complete mechanical characterization of a new vitrimer reinforced with carbon fiber. This vitrimer formulation consists of functional epoxy groups and a new dynamic disulfide crosslinks-based hardener. The testing campaign for the vitrimer composites encompassed tension, compression, interlaminar shear strength (ILSS), in-plane shear (IPS), open-hole tension (OHT) and compression (OHC), filled-hole compression (FHC) and interlaminar fracture toughness tests under mode I and II. Test conditions included room temperature and high temperature of 70 °C and 120 °C, respectively, after moisture saturation. Tension and flexural tests also were applied on the neat vitrimer resin. The results compared well with those obtained for current aeronautic materials manufactured by Resin Transfer Molding (RTM). The lower values observed in compression and ILSS derived from the thermoplastic veils included as a toughening material. This work demonstrates that the vitrimer formulation presented meets the requirements of current matrices for aeronautic-grade carbon-reinforced composites.

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“…The majority of studies in literature considering mode-II loading of fibre reinforced laminates interleaved with thermoplastic veils has been on unidirectional laminae, with only a limited number considering satin weaves. The limited studies involving 5HS laminae [6,[22][23][24][25] have configured the parent fibre orientation bias as predominantly 0° orientation [6,19,27,28]. specimens.…”

Section: Discussionmentioning

confidence: 99%

“…Modifications to matrix chemistry, fibre surface treatments, commingling with tougher fibres, interleaving [3][4][5][6][7][8][9][10][11][12][13] and through-thickness reinforcements have all presented improvements in ILFT, delamination growth resistance and damage tolerance capacity. Toughening methods using thermoplastic interleaves can allow exploitation of the tough and ductile interleave layer, which improves the ILFT in mode I and mode II, namely, GIC and GIIC [5,8,11,[14][15][16][17][18][19]. The potential to incorporate toughening at bespoke interfaces and locations with little extra cost is an added benefit only possible with interleaving in comparison to the other modification techniques mentioned above.…”

Section: Introductionmentioning

confidence: 99%

Effect of interfacial fibre orientation and PPS veil density on delamination resistance of 5HS woven CFRP laminates under mode II loading

Ramji

Grasso

et al. 2021

Composites Science and Technology

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This paper presents an experimental study on the effect of interfacial fibre orientation and interleaved thermoplastic veil on Mode II interlaminar fracture toughness of 5-harness satin woven carbon fibre reinforced polymer composite laminates. Three-point End-Notched Flexure tests were carried out to determine delamination resistance, GIIC of specimens with five fibre orientation biases and two veil densities at the midplane. Results show that delamination resistance of 5-harness satin woven laminates depends on the layup configurations at the midplane with 90/45 fibre orientation bias exhibiting the greatest resistance. The delamination resistance enhancement from polyphenylene sulfide (PPS) veil interleaves is also fibre orientation dependent but a further increase of the veil density from 10gm-2 to 20gm-2 offers little extra benefit. Fracture surface morphologies were examined under SEM to understand the failure mechanism and fracture process of the woven laminate under the combined effects of the interfacial fibre orientation and the veil density. Fibre orientation relative to the delamination path, surface texture misfit, and veil density are the three main contributors identified for the variation of delamination resistance of 5HS woven laminates.

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Mode-II fracture behaviour of aerospace-grade carbon fibre/epoxy composites interleaved with thermoplastic veils

Cited by 47 publications

References 37 publications

How Nanofibers Carry the Load: Toward a Universal and Reliable Approach for Tensile Testing of Polymeric Nanofibrous Membranes

How Nanofibers Carry the Load: Toward a Universal and Reliable Approach for Tensile Testing of Polymeric Nanofibrous Membranes

Study into the Mechanical Properties of a New Aeronautic-Grade Epoxy-Based Carbon-Fiber-Reinforced Vitrimer

Effect of interfacial fibre orientation and PPS veil density on delamination resistance of 5HS woven CFRP laminates under mode II loading

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