Hi Stephen, Falk and others,
may I refer to Landau and Lifshitz, Theory of Elasticity:
The strain tensor is derived from displacement vectors considering
two points which are closed together. It describes changes in volume
and changes in shape which describe the elastic free energy of the
given body. The stress tensor is derived considering total force on
some portion of an elastic body. It can be written as a volume
integral: integral of force per unit volume. "Thus, for any portion
of the body, each of the three components integral of Fi dV of the
resultant of all the internal stresses can be transformed into an
integral over the surface. As we know from vector analysis, the
integral of a scalar over an arbitrary volume can be transformed into
an integral of a vector, and not of a scalar. Hence the vector F,
must be the divergence of a tensor of rank two, i.e. be of the form
Fi = delta sigma ik over delta x ik. Then the force on any volume can
be written as an integral over the closed surface bounding that
volume. ...This tensor sigma ik is called the stress tensor. "
Probably Falk does not agree with this but I think its reasonable.
Anyhow I agree with Stephen that (well its common textbook knowledge)
the strain tensor is derived from displacement vectors.
May I add that I visited Falks homepage and personally dont think its
very nice to attack reviewers and editors of journals this personally
and make it public.
Cheers,
Daniel
Daniel Koehn
currently at:
Center for Advanced Studies
The Norwegian Academy of Science
Drammensveien 78, N-0271 Oslo, Norway
Tel.: +47 22 12 25 22
Fax:.+47 22 12 25 01
e-mail: [log in to unmask]
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