Analyzing Single Fiber Fragmentation Test Data by Using Stress Transfer Model

Abstract

Among the test methods to evaluate the bonding between fiber and matrix, the single fiber fragmentation (SFF) test or single fiber composite (SFC) test method is the simplest in terms of the experimental setup, and therefore commonly used. But the analysis of the SFF test data at the saturation state brings a quantity, called critical length, which is not unambiguous. Different approaches to the definition of critical length in the literature also always raised new questions and criticism. In this study we will review the analysis of the SFF test data and show different approaches to the analysis of the SFF test data by using an original stress transfer model between fiber fragments and matrix. We will show a completely new approach to the analysis of SFF test data by studying the case at which stress transfer between fiber fragments and matrix is limited by interfacial shear stress. This new approach will give us a more reliable interfacial shear strength (IFSS) that can be considered as the measure of fiber–matrix adhesion. We will also introduce a new definition of the critical length. By applying these two new ideas to the SFF test data we have, we will demonstrate that shorter fiber fragments do not necessarily mean higher IFSS contrary to the common acceptance in the literature.