Abstract Unidirectional carbon fibre/epoxy exhibits a size effect which is not necessarily consistent with the variability of specimen strengths predicted on the basis of classical Weibull theory. In some cases the variability is higher than expected and this may be due to other sources of variability in the tests apart from the material. However, in bending tests consistently lower variability than expected has been measured. This is explained qualitatively in terms of the splitting that occurs during failure which means that the composite behaves between the extremes of a brittle solid and a loose fibre bundle. This also implies that the size effect should be more strongly dependent on specimen length than indicated by Weibull theory. Three-point bending tests on specimens of different lengths but the same cross-section have been carried out which support this.
[1]
R. E. Bullock,et al.
Strength Ratios of Composite Materials in Flexure and in Tension
,
1974
.
[2]
J. Whitney,et al.
The relationship between tensile strength and flexure strength in fiber-reinforced composites
,
1980
.
[3]
W. Weibull.
A Statistical Distribution Function of Wide Applicability
,
1951
.
[4]
B. W. Rosen,et al.
Tensile failure of fibrous composites.
,
1964
.
[5]
D. C. Phillips,et al.
The effect of specimen size on the strength of cfrp
,
1978
.
[6]
Michael R Wisnom,et al.
The effect of specimen size on the bending strength of unidirectional carbon fibre-epoxy
,
1991
.