The strength of hybrid glass/carbon fibre composites

When carbon fibre is combined with less-stiff higher-elongation glass fibre in a hybrid composite an enhancement of the failure strain of the carbon fibre reinforced phase is observed. This “hybrid effect” is only partially accounted for by internal compressive strains induced by differential thermal contraction during fabrication. The predominant factor is shown to be a relationship between the strength and effective bundle size of the carbon fibre ligaments which is a consequence of the statistical distribution of strengthreducing flaws in the carbon fibres. A lamina or ligament (bundle) of carbon fibres fails when there is a local critical accumulation of fibre fractures. A model based on this concept is used to relate the two-parameter Weibull strength distribution of the carbon fibre reinforced composite phase to that of single carbon fibres. The model suggests that the critical number of fibre fractures is of the order of 3, and experimental observations of the failure process support this hypothesis.

[1]  Richard L. Smith,et al.  A probability model for fibrous composites with local load sharing , 1980, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[2]  J. Aveston,et al.  Synergistic fibre strengthening in hybrid composites , 1976 .

[3]  J. Gurland,et al.  Comparison of the statistics of two fracture modes , 1962 .

[4]  H. Morley,et al.  Aligned carbon fibre composite which approaches theoretical strength , 1980 .

[5]  B. W. Rosen,et al.  A statistical theory of material strength with application to composite materials , 1970 .

[6]  B. W. Rosen,et al.  Tensile failure of fibrous composites. , 1964 .

[7]  John M. Hedgepeth,et al.  Local Stress Concentrations in Imperfect Filamentary Composite Materials , 1967 .

[8]  W. Ko.  Finite Element Microscopic Stress Analysis of Cracked Composite Systems , 1978 .

[9]  B. Rosen.  Thermomechanical properties of fibrous composites , 1970, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[10]  M. G. Bader,et al.  The strength of hybrid glass/carbon fibre composites , 1981 .

[11]  A. Argon,et al.  Statistical Theory of Strength of Laminated Composites II , 1969 .

[12]  P. Manders.  Carbon fibre structure by electrolytic etching , 1978, Nature.

[13]  Carl Zweben,et al.  A bounding approach to the strength of composite materials , 1972 .

[14]  C. Zweben.  Tensile strength of hybrid composites , 1977 .

[15]  S. L. Phoenix,et al.  The Chain-of-Bundles Probability Model For the Strength of Fibrous Materials I: Analysis and Conjectures , 1978 .

[16]  J. Hedgepeth,et al.  Stress Concentrations from Single-Filament Failures in Composite Materials , 1969 .

[17]  C. Zweben,et al.  Tensile failure of fiber composites. , 1968 .

[18]  Bernard D. Coleman,et al.  On the strength of classical fibres and fibre bundles , 1958 .