Determination of interfacial shear strength in continuous fibre composites by multi-fibre fragmentation: A review

Edward D. McCarthy*, Constantinos Soutis

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


In a fibre-reinforced polymer matric composite (PMC), the function of the fibre is to bear the applied load that is transferred via shear stresses through the fibre-matrix interface from the polymer matrix. The fibre absorbs stress by progressively fragmenting along its axis until a critical fibre fragment length is realized. After this no further fragmentation is possible, the fibre is said to be “saturated” in stress, and it provides no strengthening upon further deformation. A critical and intrinsic material property of the composite that determines the failure of the fibre is the interfacial shear strength (IFSSh) between matrix and fibre. This review presents the multi-fibre fragmentation technique (MFFT) and Laser Raman Spectroscopy (LRS) which are used for fibre-matrix interface testing. The limitations of MFFT are summarised and ideas for improvement are proposed. The key findings of this review are: (1) MFFT equipment and protocols vary considerably and require standardisation. (2) Existing models for stress transfer between fibres rely on geometrical models that do not capture the material properties or the constitutive models of the transmitting matrix. Comprehensive constitutive matrix stress transfer models are needed. Current MFFT models do not incorporate terms for matrix vibration as a function of fibre fracture shock. It is clear that more work can also be done to characterize microcomposite systems in compression, at various angles to the fibre axis, and under various combinations of cyclic loading, but arguably such work should be pursued after the uniaxial tensile fibre fragmentation problem has been better understood.

Original languageEnglish
Pages (from-to)281-292
Number of pages12
JournalComposites Part A: Applied Science and Manufacturing
Early online date11 Jan 2019
Publication statusPublished - 1 Mar 2019


  • Composites
  • Interfacial shear strength
  • Multi-fibre fragmentation
  • Raman spectroscopy

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