A NEW METHOD TO NORMALIZE THE EFFECT OF MATRIX PROPERTIES ON THE VALUE OF INTERFACIAL SHEAR-STRENGTH OBTAINED FROM THE FRAGMENTATION TEST

A new method, based on tensile yield strength and strain, has been dev eloped to normalize the effect of matrix properties on the critical fi bre length and the interfacial shear strength obtained from the fragme ntation test. It is argued that the conventional data normalization te chnique which employs elastic properties of the matrix, is fundamental ly flawed because the model employed to calculate interfacial shear st rength assumes perfect plasticity. Single embedded fibre fragmentation in a range of epoxy resins with differing mechanical properties has b een used to validate the new method. Stoichiometric quantities of the current agent were used to keep the same interfacial chemistry. The pr oposed method provides more consistent interfacial shear strength data than existing theories. Furthermore, this normalization technique can also be used to predict the interfacial shear strength of glass fibre s embedded in a range of support resins, such as vinyl ester or epoxy resins. For these cases, a thin layer of the phenolic resin was used o n the glass fibre to keep the interface chemistry the same.