Fatigue performance of bonded crack retarders in the presence of cold worked holes and interference-fit fasteners

Abdul Syed, Xiang Zhang, James Moffatt, Robert Maziarz, Luigi Castelletti, Michael Fitzpatrick

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Abstract

Bonded crack retarders (BCR) are of particular interest in the aerospace applications for improving fatigue performance of airframe structural assemblies. In respect of structural integrity, a reinforcing strap will require additional fixing by means of riveting or bolting to ensure fail-safety. Cold expansion is currently the common practice of increasing the fatigue performance of fastener holes. Thermal residual stresses introduced during the adhesive curing process at 120°C for strap bonding are of potential concern as they may affect the cold expansion stresses and thereby the fatigue crack growth performance of the fastener hole and reinforced structural assembly. In this paper, Single-Edge-Notched Tension (SENT) specimens are made of aluminium alloy 2624-T351. Fibre metal laminate GLARE is used as BCR strap. SENT specimens with BCR and with BCR plus an interference fit fastener are used to investigate the fatigue crack growth performance. Residual stress was measured by neutron diffraction method on specimens with BCR plus fastener using neutron diffraction. It is found that the GLARE strap provides a 2.3 improvement in life comparing to a plain specimen, and a 1.75 life improvement when a fastener is installed in a cold expanded hole.

Publisher Statement: NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Fatigue. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Fatigue, [105, (2017)] DOI: 10.1016/j.ijfatigue.2017.08.023

© 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Original languageEnglish
Pages (from-to)111-118
Number of pages8
JournalInternational Journal of Fatigue
Volume105
DOIs
Publication statusPublished - 23 Aug 2017

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Keywords

  • Bonded crack retarders
  • Cold expansion
  • Fatigue crack growth
  • GLARE
  • Residual stress

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