MEASUREMENT OF THE LOAD-BEARING CAPABILITY OF THE FIBRE MATRIX INTERFACE BY SINGLE-FIBER FRAGMENTATION/

The fragmentation test is now commonly used for measuring the fibre/ma trix adhesion in a single-filament polymer composite. The limitations of the current data-reduction techniques used to calculate the value o f interfacial shear strength from the fragmentation data are identifie d. Recently, we have proposed the plasticity-effect model to predict t he stress profile in a composite containing a single discontinuous fib re. This model can also be further used to predict the stress fields i n a single-short-fibre composite where debonding occurs at the fibre/m atrix interface. In this paper, the plasticity-effect model is further developed to propose a new data-reduction technique for the fragmenta tion test. In this method, the interfacial shear stress and the tensil e stress in the individual fragments are predicted from the plasticity -effect model and the total tensile stress transferred to all of the f ibre fragments at a particular matrix strain is calculated. The total tensile stress transferred to all of the fibre fragments normalised ag ainst the fibre length is defined as the cumulative stress-transfer fu nction (CSTF). The fibre/matrix adhesion cart be predicted by assuming that a better interface is able to transfer more load to the reinforc ing fibre, which is reflected in a higher CSTF value. A glass-fibre/ep oxy system with different coupling agents is used for the validation o f this technique. (C) 1997 Elsevier Science Limited.