Table Of ContentENGINEERED
INTERFACES IN
F I B E R REINFORCED
COMPOSITES
JANG-KYO KIM & YIU-WING MA1
c f
t
ENGINEERED
INTERFACES IN
FIBER REINFORCED
COMPOSITES
ENGINEERED
INTERFACES IN
FIBER REINFORCED
COMPOSITES
Jang-Kyo Kim
Department of Mechanical Engineering
Hong Kong University of Science and Technology
Clear Water Bay, Hong Kong
Yiu-Wing Mai
Centre for Advanced Materials Technology and
Department of Mechanical & Mechatronic Engineering
University of Sydney, NSW 2006, Australia
1998
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Library of Congress Cataloging-in-Publica~oDn ata
Kim, Jang-Kyo.
Engineered interfaces in fiber reinforced composites / Jang-Kyo
Kim and Yiu-Wing, Mai. -- 1st ed.
p. cm.
Includes index.
ISBN 0-08-042695-6 (hardcover)
1. Fibrous composites. I. Mai, Y. W., 1946- . 11. Title.
TA418.9.C6K55 1998
620,1'18--DC21 97- 5 2002
CIP
First edition 1998
ISBN 0-08-042695-6
0 1998 Elsevier Science Ltd
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or
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photocopying, recording or otherwise, without permission in writing from the publishers.
Q The paper used in this publication meets the requirements of ANSUNIS0 239.48-1992
(Permanence of Paper).
Printed in The Netherlands
It is a pleasure to write the foreword to this book. This work emphasizes for the first
time in one volume how interfaces in fibrous composites can be defined, measured,
improved and optimized. Many practitioners of composites technology will find in
this book the information they have been seeking to match fiber and matrix at the
interface, thereby obtaining the best mix of properties in the final application.
Composites engineering is a relatively young field in which the test methods and
measurement techniques are not yet fully developed. Even more important, the ideas
linking the properties of composites to the interface structure are still emerging. This
book not only reviews the historic and pragmatic methods for studying composites;
but it also presents the most recent theories and fundamental tests of interface
properties. This allows the reader to find the true framework of theory to fit his/her
observations.
The fact that two brittle materials can be brought together to give a tough product
is the proof that interfaces are critical to composite properties. However, the
complexities of this process depend on the raw materials, on the surface chemistry of
the components, on the fabrication procedures, on the chemistry of hardening, and
on the damage and corrosion sustained in use. A wide view of material science,
chemistry, mechanics, process engineering and applications experience is necessary
to focus successfully on the role of the interface. The authors have demonstrated
such a global view in this volume.
I have known Professor Mai for over 20 years. He is a foremost authority on
fracture mechanics of composite materials, having studied polymer composites,
cement, ceramic and natural composite systems, in the US, Britain, Australia and
Hong Kong. In particular, he has made memorable contributions to the
understanding of cracks and to the crack-inhibiting effects seen in fibrous
composites. He has previously coauthored two books on fracture. Professor Kim
originally worked in the composites industry and has returned during the past 10
years to study interface mechanisms more closely. He is currently working in the
Hong Kong University of Science & Technology.
In summary, the topic of engineered interfaces in composites is an important one,
critical to the advance of the composites industry. Many practitioners from a range
of disciplines are seeking the information which can be found in this book. The
authors display the wide experience and theoretical knowledge necessary to provide
a critical view of the subject. I strongly recommend this volume to the composite
expert and student alike.
Kevin Kendall
Keele University, UK
May 1997
V
PREFACE
The study and application of composite materials are a truly interdisciplinary
endeavor that has been enriched by contributions from chemistry, physics, materials
scicncc, mcchanics and manufacturing cnginecring. The undcrstanding of thc
interface (or interphase) in composites is the central point of this interdisciplinary
effort. From the early development of composite materials of various nature, the
optimization of the interface has been of major importance. While there are many
reference books available on composite materials, few of them deal specifically with
the science and mechanics of the interface of fiber reinforced composites. Further,
many recent advances devoted solely to research in composite interfaces are
scattered in different published literature and have yet to be assembled in a readily
accessible form. To this end this book is an attempt to bring together recent
developments in the field, both from the materials science and mechanics
perspective, in a single convenient volume.
The central theme of this book is tailoring the interface properties to optimize the
mechanical performance and structural integrity of composites with enhanced
strength/stiffness and fracture toughness (or specific fracture resistance). It deals
mainly with interfaces in advanced composites made from high performance fibers,
such as glass, carbon, aramid, ultrahigh modulus polyethylene and some inorganic
(e.g. B/W, A1203, Sic) fibers, and matrix materials encompassing polymers, metals/
alloys and ceramics. The book is intended to provide a comprehensive treatment of
composite interfaces in such a way that it should be of interest to materials scientists,
technologists and practising engineers, as well as graduate students and their
supervisors in advanced composites. We hope that this book will also serve as a
valuable source of reference to all those involved in the design and research of
composite interfaces.
The book contains eight chapters of discussions on microstructure-property
relationships with underlying fundamental mechanics principles. In Chapter 1, an
introduction is given to the nature and definition of interfaces in fiber reinforced
composites. Chapter 2 is devoted to the mechanisms of adhesion which are specific
to each fiber-matrix system, and the physico-chemical characterization of the
interface with regard to the origin of adhesion. The experimental techniques that
have been developed to assess the fiber-matrix interface bond quality on a
microscopic scale are presented in Chapter 3, along with the techniques of
measuring interlaminar/intralaminar strengths and fracture toughness using bulk
composite laminates. The applicability and limitations associated with loading
geometry and interpretation of test data are compared. Chapter 4 presents
comprehensive theoretical analyses based on shear-lag models of' the single fiber
composite tests, with particular emphasis being placed on the interface debond
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