Plasticity - Mathematical Theory and Numerical Analysis ^!*?vHx:
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by Weimin Han B. Daya Reddy a#0GmK
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Springer 1999 .=>T yq
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The basis for the modern theory of elastoplasticity was laid in the nineteenthcentury, jj)9jUz
by Tresca, St. Venant, L´evy, and Bauschinger. Further LaE;{ jY
major advances followed in the early part of this century, the chief contributors
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during this period being Prandtl, von Mises, and Reuss. This sQA{[l!aj
early phase in the history of elastoplasticity was characterized by the introduction _e.b#{=9
and development of the concepts of irreversible behavior, yield fxDY:l
criteria, hardening and perfect plasticity, and of rate or incremental constitutive T2wn!N?r
equations for the plastic strain. 6[9E^{(z
Greater clarity in the mathematical framework for elastoplasticity theory fJCh
came with the contributions of Prager, Drucker, and Hill, during the |7Q8WjCQ{m
period just after the Second World War. Convexity of yield surfaces, and bH41#B
all its ramifications, was a central theme in this phase of the development J{mP5<8>b
of the theory. vtFA#})~
The mathematical community, meanwhile, witnessed a burst of progress (oxe\Qk
in the theory of partial differential equations and variational inequalities TKc&yAK
from the early 1960s onwards. The timing of this set of developments was 6QRfju'
particularly fortuitous for plasticity, given the fairly mature state of the !dLz ?0
subject, and the realization that the natural framework for the study of l\^q7cXG
initial boundary value problems in elastoplasticity was that of variational JXeqVKF
inequalities. This confluence of subjects emanating from mechanics and (nrrzOax
mathematics resulted in yet further theoretical developments, the outstanding ![5<\
examples being the articles by Moreau, and the monographs c
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by Duvaut and J.-L. Lions, and Temam. In this manner the stage was N,ik&NIWy
set for comprehensive investigations of the well-posedness of problems in E|9LUPcb
elastoplasticity, while the simultaneous rapid growth in interest in numer- G
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ical methods ensured that equal attention was given to issues such as the L>UYR++<6
development of solution algorithms, and their convergences. s/[i>`g/9
The interaction between elastoplasticity and mathematics has spawned i,")U)b
among many engineering scientists an interest in gaining a better understanding ^TWN_(-@
of the modern mathematical developments in the subject. In the "|DR"rr'j
same way, given the richness of plasticity in interesting and important l7{hq}@;cC
mathematical problems, many mathematicians, either students or mature !E_uQ?/w]Z
researchers, have developed an interest in understanding the mechanical savz>E&
and engineering basis of the subject, and its connections with the mathematical p2~Q
theory. While there are many textbooks and monographs on plasticity QBsDO].J<
that deal with the mechanics of the subject, they are written mainly o33{tUp'
for a readership in the engineering sciences; there does not appear to us t=\V&,
to have existed an extended account of elastoplasticity which would serve z% /ww7H
these dual needs of both engineering scientists and mathematicians. It is 0h shHv-
our hope that this monograph will go some way towards filling that gap. 0]oQ08
We present in this work three logically connected aspects of the theory of \Di~DN1
elastic-plastic solids: the constitutive theory, the variational formulations of _R(5?rG,
the related initial boundary value problems, and the numerical analysis of 'v|2}T*
these problems. These three aspects determine the three parts into which Y0B*.H
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the monograph is divided. (+]k{
The constitutive theory, which is the subject of Part I, begins with a IVNNiNN*5
motivation grounded in physical experience, whereafter the constitutive x}x@_w
theory of classical elastoplastic media is developed. This theory is then cast ~POeFZ
in a convex analytic setting, after some salient results from convex analysis , D1[}Lr=K
have been reviewed. The term “classical” refers in this work to that theory S,(@Q~
of elastic-plastic material behavior which is based on the notion of convex .;KupQ;*
yield surfaces, and the normality law. Furthermore, only the small strain, qk,cp},2K
quasi-static theory is treated. Much of what is covered in Part I will be ')1sw%[2
familiar to those working on plasticity, though the greater insights offered hTG
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by exploiting the tools of convex analysis may be new to some researchers. ''v1Pv-
On the other hand, mathematicians unfamiliar with plasticity theory will 3+|6])Hi1
find in this first part an introduction that is self-contained and accessible. _&%!4n#>
Part II of the monograph is concerned with the variational problems in (Z"Xp{u
elastoplasticity. Two major problems are identified and treated: the primal \[oHt:$do
problem, of which the displacement and internal variables are the primary #8z\i2I
unknowns; and the dual problem, of which the main unknowns are the ;5|EpoM
generalized stresses. 78QFaN$
Finally, Part III is devoted to a treatment of the approximation of the oNU* q.Q
variational problems presented in the previous part. We focus on finite element $GO'L2oLwn
approximations in space, and both semi- and fully discrete problems. I(<G;ft<}
In addition to deriving error estimates for these approximations, attention xY'g7<})$
is given to the behavior of those solution algorithms that are in common YqJIp. Z
use. )(L&+DDy
Wherever possible we provide background materials of sufficient depth `p ?E{k.N
to make this work as self-contained as possible. Thus, Part I contains a AX,Db%`l,
Preface ix ^n2w6U0
review of topics in continuum mechanics, thermodynamics, linear elasticity, "G,*Z0V5
and convex analytic setting of elastoplasticity. In Part II we include a H);'\]_'x
treatment of those topics from functional analysis and function spaces that ]czy8n$+
are relevant to a discussion of the well-posedness of vatriational problems. R]Yhuo9,&n
And Part III begins with an overview of the mathematics of finite elements. |"-,C}O
In writing this work we have drawn heavily on the results of our joint collaboration y*(YZ zF
in the past few years. We have also consulted, and made liberal UA8!?r-cR
use of the works of many: we mention in particular the major contributions #`fT%'T!
of G. Duvaut and J.-L. Lions, C. Johnson, J.B. Martin, H. !xc7~D@om(
Matthies, and J.C. Simo. While we acknowledge this debt with gratitude, OX`n`+^D
the responsibility for any inaccuracies or erroneous interpretations $($SQZK&
that might exist in this work, rests with its authors. ~JNuy"8
We thank our many friends, colleagues and family members whose interest, +-nQ,
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guidance, and encouragement made this work possible. &rd(q'Vi
W.H. h[8y$.YsC
Iowa City S }n;..{
B.D.R. ~ 9;GD4
Cape Town