Simulation of Transverse Mechanical Properties Using Interfacial Shear Stress Ratio for CF-PEI Thermoplastic Composites at Elevated Temperatures

Abstract

The mechanical properties of a fiber-reinforced composite are determined primarily by the physical properties of the fiber and the matrix and the bond strength between these two materials. The latter also depends on the manufacturing process. In this study, micromechanical analyses employing a finite element method were used to attain an understanding of these correlations. Most early models used in micromechanical analyses of fiber-reinforced composites assumed perfect interfacial bonding between the fiber and the matrix. However, in real fiber-reinforced composites, this bonding is incomplete. While the fiber/matrix interface has been an active area of study, most researchers have relied on assumptions for properties that cannot be measured. As a means of controlling stress transfer in our micromechanical analyses, a new method was devised employing the ratio between the measured interfacial sheer stress (IFSS) in single-fiber fragmentation (SFF) tests and the simulated IFSS assuming perfect interfacial bonding. In simulated transverse tensile tests, this method resulted in an error area that was 44.5 % less than that obtained under perfect bonding conditions because using the IFSS ratio reduces errors associated with the stress transfer at the fiber/matrix interface.