Chen, M., Zhang, B. orcid.org/0000-0002-0428-7745, Allegri, G. et al. (1 more author) (2024) Effects of carbon-fibre Z-pins on the through-thickness tensile strength of curved composite laminates under four-point bending. Composites Part B: Engineering, 283. 111629. ISSN 1359-8368
Abstract
This study investigates the influence of discrete through-thickness reinforcement, i.e. Z-pins, on the through-thickness tensile strength (TTS) of curved laminates through four-point bending experiments. Three types of samples are considered: unpinned, and Z-pinned with 0.27 % and 0.54 % areal densities. HexPly® IM7/8552 carbon/epoxy unidirectional prepreg with 0/±45 layup and 0.28 mm diameter T300/BMI pins were employed to manufacture the specimens. The Z-pinned laminates have comparable TTS with the unpinned samples in terms of the first observable load-drop. However, the TTS corresponding to the ultimate load-drop for low-density and high-density Z-pinned samples are 29 % and 38 % lower than for the unpinned ones, respectively. Z-pinned samples show less scatter than unpinned ones in terms of the ultimate TTS values. All specimens failed suddenly, i.e. with no evident damage progression. This implies that Z-pins were not able to form a progressive bridging zone to dissipate mechanical energy. Through a detailed meso-scale finite element analysis (FEA), it was found that the high through-thickness tensile residual stress in the Z-pin neighbourhood generated from the cool-down stage of cure is an important factor in causing the reduction in TTS of Z-pinned laminates. CT scan images of tested Z-pinned specimens show that the carbon-fibre pins experience fracture inside the laminates.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | A. Laminates; B. Delamination; C. Finite element analysis (FEA); Z-pin |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Engineering Systems and Design (iESD) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 12 Aug 2024 15:30 |
Last Modified: | 12 Aug 2024 15:30 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.compositesb.2024.111629 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:215884 |