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The Strength of Fibres in All-Ceramic Composites

Published online by Cambridge University Press:  25 February 2011

Kevin Kendall
Affiliation:
ICI New Science Group, P.O. Box 11, The Heath Runcorn, Cheshire, UK.
N. Mcn. Alford
Affiliation:
ICI New Science Group, P.O. Box 11, The Heath Runcorn, Cheshire, UK.
J. D. Birchall
Affiliation:
ICI New Science Group, P.O. Box 11, The Heath Runcorn, Cheshire, UK.
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Abstract

When considering the strength of a fibre reinforced ceramic composite, it is often assumed that the fibres retain their full strength of several GPa after cracking of the weaker matrix. The strength of the composite after matrix cracking is then calculated by the rule of mixtures as the product of fibre volume fraction and fibre strength. This paper demonstrates that such a calculation is not consistent with the principles of fracture mechanics for an isolated fibre embedded in an elastic matrix of the same elastic modulus, because the strength of the fibre is much reduced by the stress concentration arising from the matrix crack. Experimental measurements of the strength of a glass fibre embedded in a brittle matrix support the theory. The case of a fibre in a matrix of different elastic modulus is also considered, together with the proDlem of cracking along the fibre-matrix interface.

Type
Articles
Copyright
Copyright © Materials Research Society 1987

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References

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