Interfacial Adhesion Evaulation of Uniaxial fiber-Reinforced-Polymer Composites by Vibration Damping of Cantilever Beam

Abstract

The performance of fiber-reinforced

composites is often controlled by the

properties of the fiber-matrix interface. Good

interfacial bonding (or adhesion), to ensure

load transfer from matrix to reinforcement, is a

primary requirement for effective use of

reinforcement properties. Thus, a fundamental

understanding of interfacial properties and a

quantitative characterization of interfacial

adhesion strength can help in evaluating the

mechanical behavior and capabilities of

composite materials. A large number of

analytical techniques have been developed for

understanding interfacial adhesion of glass fiber

reinforced polymers. Common adhesion tests

include contact angle measurements, tension or

compression of specially shaped blocks of

polymer containing a single fiber, the single

fiber pull-out test, single-fiber fragmentation

test, short beam shear and transverse tensile

tests, and the vibration damping test. Among

these techniques, the vibration damping

technique has the advantage of being

nondestructive as well as highly sensitive for

evaluating the interfacial region, and it can

allow the materials industry to rapidly

determine the mechanical properties of

composites. In this work, we contributed a

simple optical system for measuring the

damping factor of uniaxial

fiber-reinforced-polymer composites in the

shape of cantilever beams. A single glass fiber-

and three single metallic wire-reinforced epoxy

resin composites were tested with the optical

system. The fiber- (wire-) matrix interfacial

adhesion strength measurements were made by

microbond test. A reasonable agreement was

found between the measured interfacial

adhesion strength and micromechanics

calculations using results from vibration

damping experiments. The study was also

extended to multi-fiber composites. The

interfacial damping factors in glass-fiber

reinforced epoxy-resin composites were

correlated with transverse tensile strength,

which is a qualitative measurement of adhesion

at the fiber-matrix interface. Four different

composite systems were tested. For each

system, glass fibers with three different surface

treatments were used at three different volume

fractions. The experimental results also showed

an inverse relationship between damping

contributed by the interface and composite

transverse tensile strength for all of the

multi-fiber composites.