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Journal of Materials Science

, Volume 30, Issue 22, pp 5607–5616 | Cite as

Fragmentation of aramid fibres in single-fibre model composites

  • M. C. Andrews
  • R. J. Young
Papers

Abstract

Raman spectroscopy has been used to monitor the state of axial stress along fragmented, high-modulus Kevlar 149 aramid fibres in an epoxy resin matrix by monitoring the peak position of the strain-sensitive 1610 cm−1 aramid Raman band along individual fragments. It is shown that the interfacial shear stress along each fragment, derived from the strain distribution profiles, is not constant as assumed by conventional fragmentation analysis. The fragmentation process of as-received Kevlar 149 fibres is compared to that of irradiated Kevlar 149 fibres exposed to ultraviolet light where the tensile strength and modulus of the fibres have been reduced. It is found that the derived interfacial shear stress and interfacial shear strength values are higher for those fibres exposed to ultraviolet light compared with the as-received fibres. It is also clearly demonstrated that the values of interfacial shear strength calculated at high matrix strains from conventional fragmentation analysis are considerably lower than the maximum value of interfacial shear stress prior to fibre fracture that was found to be close to the shear yield stress of the resin matrix. Hence the determination of the interfacial shear strength following the saturation of the fragmentation process may give rise to misleading results.

Keywords

Tensile Strength Shear Strength Raman Spectroscopy Ultraviolet Light Raman Band 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

ef

Fibre strain

em

Matrix strain

efmax

Maximum strain along each fragment

ef*

Failure strain of the fibre

Ef

Fibre tensile modulus

lc

Critical fragment length

lc

Mean critical fragment length

lf

Fragment length

r

Fibre radius

x

Distance along the fibre

σfmax

Maximum stress along each fragment

σf*

Fibre tensile strength

τ

Interfacial shear stress

τs

Interfacial shear strength

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Copyright information

© Chapman & Hall 1995

Authors and Affiliations

  • M. C. Andrews
    • 1
  • R. J. Young
    • 1
  1. 1.Manchester Materials Science CentreUMIST/University of ManchesterManchesterUK

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