Network Theory

The theory of networks of inextensible fibers was formulated by Rivlin [1] as a theory of materials like fish-nets, which have small resistance to distortion but high resistance to stretching. The theory is a continuum theory, in which individual cords or

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e •.

CONTINUUM THEORY OF THE MECHANICS OF FIBRE-REINFO RCED COMPOSITES

EDITED BY

A.J.M. SPENCER THE UNIVERSITY OF NOTTINGHAM

SPRINGER-VERLAG WIEN GMBH

This work is subjtd to copyright. All righ ts are reserved, whether the whole or part of the material is concemed specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks.

© 1984 by Springer-Verlag Wien Originally published by Springer-Verlag Wien-New York in 1984

ISBN 978-3-211-81842-8 DOI 10.1007/978-3-7091-4336-0

ISBN 978-3-7091-4336-0 (eBook)

PREFACE

This booK is made up of tne notes for tne lectures 6ze .-"ive au6zors gave at the International Centre for 1981.

Mecizanica~

Sciences in Udilie in Jdy

The aim of the Scizool was to present an account of rec

(a+b)

/cos~

For this we introduce unit vectors c and d, where ,

d

~(a-b) /sin~

b

:

, (46)

a = : cos 4J + ~

sin~

,

cos~

-

~ sin~

.

On substituting for a and b from (46) into (44), we obtain an expression for W of the same form as (35), with a and b replaced by c and d respectively, and with the coefficients becoming functions of cos

2~.

Hence this case also corresponds to orthotropic symmetry, and if c and d are chosen to lie in the x 1 and x 2 coordinate directions, the constitutive equation assumes the form (37) .

There are again nine independent elastic

coefficients, which are functions of

cos2~.

The constitutive equation in

terms of c and d is obtained by substituting for a and b from (46) into (45). The expression is obviously complicated.

An alternative and rather

simpler procedure is to observe from the beginning that W can be expressed

Constitutive Theory

15

as a function of e, c, d and

cos2~,

with c.d

= 0.

Hence it is possible

to proceed as in the case of orthogonal fibres, with a and b replaced by c and d, and the coefficients in the expression for W regarded as functions of

cos2~.

However, with the alternative procedure it is less

easy to proceed to the case of fibre inextensibility. If the material is incompressible then tr e = 0

A,

involving stress

-p~

y3

andy~

is added.

directions, then a.e.a

and the terms

are omitted from (44) and (45), and a reaction If the material is inextensible in both fibre

=0

and b.e.b

= O,

and (45) is replaced by

(47) The number of independent elastic constants is reduced to five, and the last two terms represent the reaction stress.

In terms of the vectors c

and d, (47) is

a

Az tr :

+ 211: + { h ~ cos 2~ tr : + 2y 2

(:.:.:

cos 2