Residual stresses in structures reinforced with adhesively bonded straps designed to retard fatigue crack growth

C. D M Liljedahl, M. E. Fitzpatrick, L. Edwards

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The residual stresses induced when adhesively bonding patches to a 7085 alloy SENT (side edge notched tension) specimen in order to produce fatigue crack growth retardation have been investigated. Knowledge of the induced residual stresses is important as they affect the beneficial bridging effect of the strap. The strap materials studied were: Titanium, GLARE (fibre metal laminate), GFRP (glass fibre reinforced polymer) and CFRP (carbon fibre reinforced polymer). The residual stresses were measured using neutron diffraction and are compared with those predicated by FE (finite element) simulation. The measured and modelled residual stresses were in reasonable correlation. Tensile residual stresses were found close to the strap, whereas small compressive residual stresses were found on the un-bonded side. The residual stresses were induced due to the mismatch in the coefficient of thermal expansion (ΔCTE) between the SENT and the strap. The magnitude of the stresses induced by the bonded crack retarders depend both on the ΔCTE and the stiffness ratio between the reinforced structure and the strap. For the straps studied, the magnitude of the peak residual stresses found were in the following descending order: CFRP, titanium, GFRP and GLARE.

Original languageEnglish
Pages (from-to)344-355
Number of pages12
JournalComposite Structures
Volume86
Issue number4
Early online date24 Oct 2007
DOIs
Publication statusPublished - 1 Dec 2008
Externally publishedYes

Keywords

  • Bonded crack retarders
  • Crack growth retardation
  • Finite element analysis
  • Neutron diffraction
  • Residual stresses

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Ceramics and Composites

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