Investigation of interfacial strength parameters in polymer matrix composites: Compatibility and reproducibility

Abstract

Effects of various geometrical and physical factors, as well as the method of data reduction (analysis of experimental force–displacement curves) on the values of local interfacial strength parameters (local IFSS, τd, and critical energy release rate, Gic) determined by means of a single fiber pull-out test are discussed. Experimental results of our pull-out tests on several fiber–polymer matrix systems showed that τd and Gic weakly depended on geometrical factors. However, the pull-out test appeared to be sensitive to the conditions of specimen formation and testing, such as changing the nature of the contacting surfaces (fiber sizing) and the fiber pull-out rate. Of several methods of τd and Gic determination from a force–displacement curve, the most reliable and reproducible one is the approach based on the values of the maximum force recorded in a pull-out test and the interfacial frictional force immediately after fiber debonding. Keywords: Polymer matrix composites, Pull-out test, Local interfacial shear strength, Critical energy release rate, Geometrical factors, Analysis of force-displacement curves