Mode II delamination resistance of composites reinforced with inclined Z-pins

Beene M'Membe, Sam Gannon, Mehdi Yasaee, Stephen R Hallett, Ivana K Partridge

Research output: Contribution to journalSpecial issue (Academic Journal)peer-review

57 Citations (Scopus)
382 Downloads (Pure)


Z-pin reinforcements in composite materials significantly enhance the through-thickness strength by providing strong bridging forces on the delaminated surfaces of a damaged laminate. The bridging forces have been shown to be more effective in mode I dominated delamination cracks than in mode II shear dominated cracks. One solution to help improve the Mode II delamination resistance of Z-pins is to incline the pins such that the angle between the longitudinal axis of the pin and the shear force load vector is reduced. In this study, the Mode II resistance of laminated composite reinforced through the thickness with inclined Z-pins is characterised. There is a notable increase in the apparent fracture toughness of composites when Z-pins are better aligned with the shear load vector (inclined) compared to the conventional, orthogonally inserted Z-pins. Brittle, catastrophic failure however occurs when the inclined Z-pins are angled against the shear load vector. For many structures the direction of the local direction of shear load cannot always be predicted, therefore a general approach for inclined Z-pins using a ±θ configuration was also investigated. With this setup, a modest improvement in the apparent fracture toughness was obtained.
Original languageEnglish
Pages (from-to)565-572
Number of pages8
JournalMaterials and Design
Early online date14 Jan 2016
Publication statusPublished - 26 Jan 2016

Structured keywords

  • Composites UTC


  • Z-pins
  • Inclined Insertion
  • Fracture Toughness


Dive into the research topics of 'Mode II delamination resistance of composites reinforced with inclined Z-pins'. Together they form a unique fingerprint.

Cite this