AN IMPROVED ANALYSIS FOR AXISYMMETRICAL STRESS DISTRIBUTIONS IN THE SINGLE-FIBER PULL-OUT TEST

Elastic stress transfer in the fibre pull-out problem has been investi gated quite extensively using various shear lag analyses. These analys es grossly underestimate the severity of the stress concentration at t he fibre-matrix interface. In this study, by using the total complemen tary energy approach, it is found that a stress concentration zone exi sts at the interface near the fibre entry. Compared to shear lag analy sis, the interfacial radial stress at the fibre entry is found to be m uch higher and the interfacial shear stress reaches a maximum not at t he entry end of the fibre but in a few fibre diameters from it. It is also shown that the magnitudes of these stress peaks reduce with incre asing b/a and L/a ratios. At large b/a and L/a ratios, the maximum rad ial and shear stresses at the interface reach a plateau and are indepe ndent of the loading methods considered. Finally, the implications of these stress concentrations on the failure of the matrix and interface and the specimen geometry in determining the interfacial shear streng th are discussed.