Adhesion Effect on the Tensile Properties of Fibre Reinforced Composite Materials

Abstract

The effect of adhesion between glass fibre and matrix on the tensile strength of two kinds of F.R.P. containing continuous or discontinuous glass fibres has been theoretically and experimentally discussed.The tensile behavior of F.R.P. containing continuous glass fibres is entirely similar to that of the blended fibres composed of two different kinds of fibres, so that the adhesion effect on the tensile strength of such F.R.P. is negligible.The shearing strength of adhesion τjmax between glass fibre and matrix of polystylene in the composite material containing discontinuous glass fibres has been obtained from the experimental data by means of the following formulae.σc=Vf·(1-lc/2l)·σfmax+(1-Vf)·σm1 and lc=σfmaxd/2τjmax, and its value is about 0.08-0.18kg/mmmm2. In those formulae, σc is the tensile strength of the composite, Vf the volume content of glass fibres, lc the critical length, l the fibre length, σfmax the tensile strength of fibre, σm1 the tensile strength of matrix at the breaking strain of fibre and d the diameter of fibre.The value of τjmax, obtained experimentally here to be 0.08-0.18kg/mmmm2, decreases with increasing fibre length, and is far lower than the shearing strength of matrix or that of joint between glass plate and polystylene knob.