Indexed by:期刊论文

Date of Publication:2010-11-01

Journal:OPTICS AND LASERS IN ENGINEERING

Included Journals:SCIE、EI、Scopus

Volume:48

Issue:11,SI

Page Number:1089-1095

ISSN No.:0143-8166

Key Words:Interface; Polymer coating; Fiber/microdroplet tensile test; Stress transfer; Micro-Raman spectroscopy

Abstract:The single fiber/microdroplet tensile test is applied for evaluating the interfacial mechanics between a fiber and a resin substrate It is used to investigate the influence of a polymer coating on a Kevlar-29 fiber surface, specifically the stress transfer between the fiber and epoxy resin in a microdroplet. Unlike usual tests, this new test ensures a symmetrical axial stress on the embedded fiber and reduces the stress singularity that appears at the embedded fiber entry Using a homemade loading device, symmetrical tensile tests are performed on a Kevlar-29 fiber with or without polyvinylchloride (PVC) coating, the surface of which is in contact with two epoxy resin microdroplets during curing Raman spectra on the embedded fiber are recorded by micro-Raman Spectroscopy under different strain levels. Then they are transformed to the distributions of fiber axis stress based on the relationship between stress and Raman shift The Raman results reveal that the fiber axial stresses increase with the applied loads, and the antisymmetric interfacial shear stresses, obtained by a straightforward balance of shear-to-axial forces argument, lead to the appearance of shear stress concentrations at a distance to the embedded fiber entry The load is transferred from the outer fiber to the embedded fiber in the epoxy microdroplet As is observed by scanning electronic microscopy (SEM), the existence of a flexible polymer coating on the fiber surface reduces the stress transfer efficiency (C) 2009 Elsevier Ltd All rights reserved