New interlaminar features and void distributions in advanced aerospace-grade composites revealed via automated algorithms using micro-computed tomography
New interlaminar features and void distributions in advanced aerospace-grade composites revealed via automated algorithms using micro-computed tomography
X-ray micro-computed tomography (μCT) is used to quantify morphology in AS4/8552 (autoclave) and IM7/M56 (Out-of-Autoclave, OoA) aerospace-grade advanced unidirectional-ply carbon fiber prepreg composites, revealing several previously unreported features. The micron-scale (1 μm voxel size) three-dimensional datasets combined with automated, objective algorithms, revealed the following previously unreported features of AS4/8552 and IM7/M56 laminates, respectively: all ply interfaces analyzed have misplaced microfibers at densities of 1–2 per mm2 of interface area that can contribute to the mean thickness of the interlaminar regions of 8.6 μm and 14.4 μm; all ply interfaces have elongated (aspect ratio > 10 and presumed to extend indefinitely) periodic resin pockets along the microfiber direction of the plies bounding the interlaminar region that we term tow-aligned resin pockets (TARPs), with typical thicknesses that are 2–3X greater than the average interlaminar thickness; overall void fractions are low at ~0.002 vol% and ~0.001 vol%, comprised primarily of newly-quantified "sub-microvoids" with an average volume of 26–31 μm3 that are equally pervasive in both materials, numbering ~300 per mm3. The new interlaminar region and void tools were also utilized to analyze laminates with aligned carbon nanotubes (A-CNTs), termed "nanostitches", incorporated between plies to reinforce the interlaminar regions. The addition of A-CNTs increased the interlaminar thickness by 2.2 μm and 8.0 μm for the AS4/8552 and IM7/M56 systems, respectively, but did not affect the quantity or distribution of voids or TARPs. These newly-identified features are relevant to the mechanical performance of such composites, as they may have positive or negative effects on damage initiation and progression.
Carbon Fiber, Carbon Nanotubes, Composites, Micro-computed Tomography
Fritz, Nathan K.
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Kopp, Reed
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Nason, Abigail K.
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Ni, Xinchen
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Lee, Jeonyoon
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Stein, Itai Y.
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Kalfon-Cohen, Estelle
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Sinclair, Ian
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Spearing, Mark
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Camanho, Pedro P.
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Wardle, Brian L.
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16 June 2020
Fritz, Nathan K.
fb95a7ba-3ef3-4920-9770-d44273843f95
Kopp, Reed
b5a801fe-f1e2-406c-a070-73bac41796b3
Nason, Abigail K.
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Ni, Xinchen
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Lee, Jeonyoon
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Stein, Itai Y.
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Kalfon-Cohen, Estelle
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Sinclair, Ian
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Spearing, Mark
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Camanho, Pedro P.
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Wardle, Brian L.
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Fritz, Nathan K., Kopp, Reed, Nason, Abigail K., Ni, Xinchen, Lee, Jeonyoon, Stein, Itai Y., Kalfon-Cohen, Estelle, Sinclair, Ian, Spearing, Mark, Camanho, Pedro P. and Wardle, Brian L.
(2020)
New interlaminar features and void distributions in advanced aerospace-grade composites revealed via automated algorithms using micro-computed tomography.
Composites Science and Technology, 193, [108132].
(doi:10.1016/j.compscitech.2020.108132).
Abstract
X-ray micro-computed tomography (μCT) is used to quantify morphology in AS4/8552 (autoclave) and IM7/M56 (Out-of-Autoclave, OoA) aerospace-grade advanced unidirectional-ply carbon fiber prepreg composites, revealing several previously unreported features. The micron-scale (1 μm voxel size) three-dimensional datasets combined with automated, objective algorithms, revealed the following previously unreported features of AS4/8552 and IM7/M56 laminates, respectively: all ply interfaces analyzed have misplaced microfibers at densities of 1–2 per mm2 of interface area that can contribute to the mean thickness of the interlaminar regions of 8.6 μm and 14.4 μm; all ply interfaces have elongated (aspect ratio > 10 and presumed to extend indefinitely) periodic resin pockets along the microfiber direction of the plies bounding the interlaminar region that we term tow-aligned resin pockets (TARPs), with typical thicknesses that are 2–3X greater than the average interlaminar thickness; overall void fractions are low at ~0.002 vol% and ~0.001 vol%, comprised primarily of newly-quantified "sub-microvoids" with an average volume of 26–31 μm3 that are equally pervasive in both materials, numbering ~300 per mm3. The new interlaminar region and void tools were also utilized to analyze laminates with aligned carbon nanotubes (A-CNTs), termed "nanostitches", incorporated between plies to reinforce the interlaminar regions. The addition of A-CNTs increased the interlaminar thickness by 2.2 μm and 8.0 μm for the AS4/8552 and IM7/M56 systems, respectively, but did not affect the quantity or distribution of voids or TARPs. These newly-identified features are relevant to the mechanical performance of such composites, as they may have positive or negative effects on damage initiation and progression.
Text
uCT Quantification Fritz V4.2 small_blwclean
- Accepted Manuscript
More information
Accepted/In Press date: 16 March 2020
e-pub ahead of print date: 19 March 2020
Published date: 16 June 2020
Additional Information:
Funding Information:
This work was supported by ANSYS, Airbus, Embraer, Lockheed Martin, Saab AB, Saertex, and Teijin Carbon America through MIT's Nano-Engineered Composite aerospace STructures (NECST) Consortium, National Funds through FCT – Fundação para Ciência e a Technologia in the scope of project MITP-TB/PFM/0005/2013 , the Office of Naval Research (ONR) under grant number ONR.N000141712068 , the NASA Space Technology Research Institute (STRI) for Ultra-Strong Composites by Computational Design (US-COMP) grant NNX17AJ32G, and through the Defense University Research Instrumentation Program (DURIP) for micro-computed tomography instrumentation support by ONR under grant number ONR.N000141712068. The authors thank Hexcel and Saab AB for donation of material. NKF and RK acknowledge support from the National Science Foundation Graduate Research Fellowship under Grant No. 1122374 . AKN was supported by the CMSE Research Experience for Undergraduates Program, as part of the MRSEC Program of the National Science Foundation under Grant Number DMR-08-19762 , and the MIT Materials Research Laboratory (MRL). This work made use of facilities supported in part by the U. S. Army Research Office through the Institute for Soldier Nanotechnologies at MIT, under Cooperative Agreement Number W911NF-18-2-0048, the U.S. Army Natick Soldier R, D&E Center (NSRDEC), and MIT's Microsystems Technology Laboratories (MTL).
Publisher Copyright:
© 2020 Elsevier Ltd
Keywords:
Carbon Fiber, Carbon Nanotubes, Composites, Micro-computed Tomography
Identifiers
Local EPrints ID: 439102
URI: http://eprints.soton.ac.uk/id/eprint/439102
ISSN: 0266-3538
PURE UUID: c3f57ba1-3ef7-4517-8dcf-d2acc9eb6655
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Date deposited: 03 Apr 2020 16:30
Last modified: 17 Mar 2024 05:27
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Contributors
Author:
Nathan K. Fritz
Author:
Reed Kopp
Author:
Abigail K. Nason
Author:
Xinchen Ni
Author:
Jeonyoon Lee
Author:
Itai Y. Stein
Author:
Estelle Kalfon-Cohen
Author:
Pedro P. Camanho
Author:
Brian L. Wardle
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