438
R.
W.
Ogden
since the
1940’s,
stimulated by the need to describe and explain the
mechanical behaviour
of
materials, such
as
natural rubber, which are
capable of undergoing large elastic deformations. The fabrication
of
synthetic rubber-like materials has provided further stimulus, and,
more recently, application
of
the theory to the study of the mechanics
of
biological tissues has been much in evidence. The range of appli-
cations is growing, a.nd nonlinear elasticity can now be regarded
as
very much an interdisciplinary subject area, impinging on engineer-
ing, materials science, chemistry, physics and biology. The inherent
nonlinearity of the mathematical theory presents many difficulties
but it also offers
a
wealth
of
exciting and challenging opportunities
for researchers in
a
diversity
of
fields, but notably in theoretical me-
chanics, applied mathematics, pure mathematics, numerical analysis
and computational mechanics.
In
this article the intention is not to provide
a
comprehensive
account
of
nonlinear elasticity but to concentrate
on
the main in-
gredients of the theory and to illustrate how the nonlinearity influ-
ences the nature
of
the solution of some very simple boundary-value
problems. Different flavours
of
the theory, with varying degrees of
mathematical sophistication, are encountered
in
the literature, and
the reader is referred to the texts by Truesdell and No11
[20],
Marsden
a.nd Hughes
[ll],
Ogden
[14]
and Ciarlet
[GI,
in particular, for more
details
of
the theory. Only
a
limited number of selected papers are
cited here and in general, rather than give full documentation, we
point to the above-mentioned monographs for references to original
sources; see also the recent review article by Beatty
[4].
2
Basic Equations
2.1
Kinematics
We consider
a
continuous body which occupies
a
connected open
subset of
a
three-dimensional Euclidean point space, and we refer to
such
a
subset
as
a
configuration
of
the body. We identify an arbitrary
configuration as
a
reference configuration
and denote this by
B,.
Let
points in
B,
be labelled by their position vectors
X
relative
to
an