Plasticity - Mathematical Theory and Numerical Analysis z5 Bi=~=#
Ivsb<qzG
by Weimin Han B. Daya Reddy CN/IH
1i
u =Y
Springer 1999 nX._EC
R*yU<9Mm8
2/@D7>F&g
The basis for the modern theory of elastoplasticity was laid in the nineteenthcentury, 7IW> >RBF
by Tresca, St. Venant, L´evy, and Bauschinger. Further I_?He'=0oU
major advances followed in the early part of this century, the chief contributors {7X#4o0
during this period being Prandtl, von Mises, and Reuss. This >dk9f}7-
early phase in the history of elastoplasticity was characterized by the introduction .jU Z
and development of the concepts of irreversible behavior, yield ]NtSu%u
criteria, hardening and perfect plasticity, and of rate or incremental constitutive S8%n .<OB
equations for the plastic strain. JvkL37^n:
Greater clarity in the mathematical framework for elastoplasticity theory u?kD)5Nk
came with the contributions of Prager, Drucker, and Hill, during the g]|_
`
period just after the Second World War. Convexity of yield surfaces, and YdI0E
all its ramifications, was a central theme in this phase of the development A:eG5K}
of the theory. kM!V.e[g
The mathematical community, meanwhile, witnessed a burst of progress 8%[HYgd5)
in the theory of partial differential equations and variational inequalities Q2eXK[?*
from the early 1960s onwards. The timing of this set of developments was |) Pi6Y
particularly fortuitous for plasticity, given the fairly mature state of the Ziz=]D_
subject, and the realization that the natural framework for the study of w>qCg XU3
initial boundary value problems in elastoplasticity was that of variational G
AQ
'Ti1!
inequalities. This confluence of subjects emanating from mechanics and !9r:&n.\
mathematics resulted in yet further theoretical developments, the outstanding H?uukmZl
examples being the articles by Moreau, and the monographs 6^;^rUlm
by Duvaut and J.-L. Lions, and Temam. In this manner the stage was YUscz!rM
set for comprehensive investigations of the well-posedness of problems in 'S?;J ,/
elastoplasticity, while the simultaneous rapid growth in interest in numer- ID4~Gn
ical methods ensured that equal attention was given to issues such as the s*Ih_Ag=:
development of solution algorithms, and their convergences. 4<.O+hS
The interaction between elastoplasticity and mathematics has spawned ;xK_qBIP
among many engineering scientists an interest in gaining a better understanding u g\w\b
of the modern mathematical developments in the subject. In the Qw?+!-7TN
same way, given the richness of plasticity in interesting and important bC~~5Cm
mathematical problems, many mathematicians, either students or mature Fc8E Y*
researchers, have developed an interest in understanding the mechanical HR60
and engineering basis of the subject, and its connections with the mathematical ;LRW
8Wd
theory. While there are many textbooks and monographs on plasticity ''S&e
that deal with the mechanics of the subject, they are written mainly \&a.}t
for a readership in the engineering sciences; there does not appear to us .
uR M{Bs
to have existed an extended account of elastoplasticity which would serve <tbZj=*O/o
these dual needs of both engineering scientists and mathematicians. It is $D'^t(
our hope that this monograph will go some way towards filling that gap. WA.AFt
We present in this work three logically connected aspects of the theory of i-W
elastic-plastic solids: the constitutive theory, the variational formulations of Fk1.iRVzi
the related initial boundary value problems, and the numerical analysis of ni6r{eSQ
these problems. These three aspects determine the three parts into which TJaeQqob
the monograph is divided. Rg* J}
The constitutive theory, which is the subject of Part I, begins with a $
[7 Vgs
motivation grounded in physical experience, whereafter the constitutive X
\f[
theory of classical elastoplastic media is developed. This theory is then cast ([ dT!B#aH
in a convex analytic setting, after some salient results from convex analysis EfiU$8y
have been reviewed. The term “classical” refers in this work to that theory \ZD[!w7
of elastic-plastic material behavior which is based on the notion of convex \DA$6w\\
yield surfaces, and the normality law. Furthermore, only the small strain, XoR>H4xh
quasi-static theory is treated. Much of what is covered in Part I will be \k@Z7+&7
familiar to those working on plasticity, though the greater insights offered 1$ML #5+,
by exploiting the tools of convex analysis may be new to some researchers. hazq#J!
On the other hand, mathematicians unfamiliar with plasticity theory will @(:v_l
find in this first part an introduction that is self-contained and accessible. g:<?
Part II of the monograph is concerned with the variational problems in M=y0PCD
elastoplasticity. Two major problems are identified and treated: the primal n.hElgkUOr
problem, of which the displacement and internal variables are the primary W#XG;
unknowns; and the dual problem, of which the main unknowns are the 5]"SGP
generalized stresses. dTGA5c
Finally, Part III is devoted to a treatment of the approximation of the M3pjXc<O
variational problems presented in the previous part. We focus on finite element #Qbl=o4
approximations in space, and both semi- and fully discrete problems. ?_q+&)4-o
In addition to deriving error estimates for these approximations, attention W
f@t4(i
is given to the behavior of those solution algorithms that are in common (][LQ6Pc
use. 8LJ{i%
Wherever possible we provide background materials of sufficient depth ;=jr0\| e
to make this work as self-contained as possible. Thus, Part I contains a [B^ G-
Preface ix l#bAl/c`
review of topics in continuum mechanics, thermodynamics, linear elasticity, ksWSMxm
and convex analytic setting of elastoplasticity. In Part II we include a O8|*M "
treatment of those topics from functional analysis and function spaces that x*}bo))hb
are relevant to a discussion of the well-posedness of vatriational problems. GBP-V66
And Part III begins with an overview of the mathematics of finite elements.
/\=MBUN
In writing this work we have drawn heavily on the results of our joint collaboration ] hE="z=n
in the past few years. We have also consulted, and made liberal KJh,,xI>by
use of the works of many: we mention in particular the major contributions v-`h>J!Nx
of G. Duvaut and J.-L. Lions, C. Johnson, J.B. Martin, H. "Xn%at4
Matthies, and J.C. Simo. While we acknowledge this debt with gratitude, feEMg
the responsibility for any inaccuracies or erroneous interpretations 7Kf}O6nE
that might exist in this work, rests with its authors. ](K0Fwo`;"
We thank our many friends, colleagues and family members whose interest, &~-~5B|3"
guidance, and encouragement made this work possible. /#S>sOg2xq
W.H. 5j^NV&/_
Iowa City V 0{tap}
B.D.R. w([$@1]
Cape Town