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Elastomers are found in many applications ranging from technology to daily life applications for example in tires, drive systems, sealings and print rollers. Dynamical operation conditions put extremely high demands on the performance and stability of these materials and their elastic and flow properties can be easily adjusted by simple manipulations on their elastic and viscous properties.

However, the required service life suffers often from material damage as a result of wear processes such as abrasion and wear fatigue, mostly caused by crack formation and propagation.

This book covers interdisciplinary research between physics, physical chemistry, material sciences and engineering of elastomers within the range from nanometres to millimetres and connects these aspects with the constitutive material properties. The different chapters describe reliable lifetime and durability predictions based on new fracture mechanical testing concepts and advanced material-theoretical methods which are finally implemented in the finite element method for structural simulations.

The use of this approach allows a realistic description of complex geometrical and loading conditions which includes the peculiarities of the mechanical behaviour of elastomeric materials in detail. Furthermore, this approach demonstrates how multi-scale research concepts provide an ambitious interdisciplinary challenge at the interface between engineering and natural sciences.

This book covers the interests of academic researchers, graduate students and professionals working in polymer science, rubber and tire technology and in materials science at the interface of academic and industrial research.

The IUTAM Symposium on "Non-Linear Singularities in Defonnation and Flow" took place from March 17 to 21, 1997, at the Technion in Haifa, Israel, with 70 participants from 12 countries. The leitmotif of this Symposium brought together scientists working on singularity-dominated local fields in various branches of continuum mechanics, covering traditional solid and liquid behaviour as well as that of more complex non-linear materials; non-linearities arise either from the constitutive equations for the material or from the presence of interfaces or both. The scientific committee invited speakers who presented 34 papers in 12 sessions. Topics covered in the lectures included near tip fields of cracks, notches and wedges; flow around comers, wedges and cones; interfacial phenomena; moving contact lines in multiphase systems; cusps in fluid interfaces and shocks and localization. There was a general consensus among the participants that singularities induced by non-linearities provide a challenging and currently important area of research in mechanics, engineering and applied mathematics. Presentation and discussions during the symposium initiated further studies of problems in these interesting areas. This volume contains 30 full length papers, submitted by the lecturers after the symposium and reviewed to the standards of international scientific periodicals. It is our pleasure to acknowledge the efficient and tireless help of Mrs. Alice Goodman and Mr. Gideon Wachsman of the Faculty of Aerospace Engineering at the Technion. David Durban Anthony Pearson Haifa Cambridge April 1998 IX International Scientific Committee C. Atkinson (UK) G. I. Barenblatt (USA) H. -c.
This book is the standard text book of elastoplasticity in which the elastoplasticity theory is comprehensively described from the conventional theory for the monotonic loading to the unconventional theory for the cyclic loading behavior. Explanations of vector-tensor analysis and continuum mechanics are provided first as a foundation for elastoplasticity theory, covering various strain and stress measures and their rates with their objectivities.

Elastoplasticity has been highly developed by the creation and formulation of the subloading surface model which is the unified fundamental law for irreversible mechanical phenomena in solids. The assumption that the interior of the yield surface is an elastic domain is excluded in order to describe the plastic strain rate due to the rate of stress inside the yield surface in this model aiming at the prediction of cyclic loading behavior, although the yield surface enclosing the elastic domain is assumed in all the elastoplastic models other than the subloading surface model. Then, the plastic strain rate develops continuously as the stress approaches the yield surface, providing the advantages: 1) The tangent modulus changes continuously, 2) The yield judgment whether the stress reaches the yield surface is not required, 3) The stress is automatically attracted to the yield surface even when it goes out from the yield surface by large loading increments in numerical calculation and 4) The finite strain theory based on the multiplicative decomposition of deformation gradient tensor is formulated exactly. Consequently, the monotonic, the cyclic, the non-proportional loading behaviors for wide classes of materials including soils, rocks and concretes in addition to metals can be described rigorously by the subloading surface model.

Further, the viscoplastic constitutive equations in a general rate from the quasi-static to the impact loadings are described, and constitutive equations of friction behavior and its application to the prediction of stick-slip phenomena, etc. are also described in detail. In addition, the return-mapping algorithm, the consistent tangent modulus, etc. are explained for the numerical analyses. Further, the damage, the phase-transformation and the crystal plasticity models are also described in brief. All of them are based on the subloading surface model. The elastoplasticity analysis will be advanced steadily based on the subloading surface model.

Recent developments in engineering and technology have brought about serious and enlarged demands for reliability, safety and economy in wide range of fields such as aeronautics, nuclear engineering, civil and structural engineering, automotive and production industry. This, in turn, has caused more interest in continuum damage mechanics and its engineering applications.

This book aims to give a concise overview of the current state of damage mechanics, and then to show the fascinating possibility of this promising branch of mechanics, and to provide researchers, engineers and graduate students with an intelligible and self-contained textbook.

The book consists of two parts and an appendix. Part I is concerned with the foundation of continuum damage mechanics. Basic concepts of material damage and the mechanical representation of damage state of various kinds are described in Chapters 1 and 2. In Chapters 3-5, irreversible thermodynamics, thermodynamic constitutive theory and its application to the modeling of the constitutive and the evolution equations of damaged materials are descried as a systematic basis for the subsequent development throughout the book.

Part II describes the application of the fundamental theories developed in Part I to typical damage and fracture problems encountered in various fields of the current engineering. Important engineering aspects of elastic-plastic or ductile damage, their damage mechanics modeling and their further refinement are first discussed in Chapter 6. Chapters 7 and 8 are concerned with the modeling of fatigue, creep, creep-fatigue and their engineering application. Damage mechanics modeling of complicated crack closure behavior in elastic-brittle and composite materials are discussed in Chapters 9 and 10. In Chapter 11, applicability of the local approach to fracture by means of damage mechanics and finite element method, and the ensuing mathematical and numerical problems are briefly discussed.

A proper understanding of the subject matter requires knowledge of tensor algebra and tensor calculus. At the end of this book, therefore, the foundations of tensor analysis are presented in the Appendix, especially for readers with insufficient mathematical background, but with keen interest in this exciting field of mechanics.

[1] SAINT-VENANT, B. DE: Memoires des savants etrangers, Vol. 14, 1855. [2] BREDT, R.: Kritische Bemerkungen zur Drehungselastizitat. Z. VDl40 (1968) 785. [3] PRANDTL, L.: Zur Torsion von prismatischen Staben. Phys. Z. 4 (1903) 758. [4] FOPPL, A.: Der Drillingswiderstand von Walzeisentragern. Z. VDl61 (1917) 694. [5] FOPPL, A., and L. FOPPL: Drang und Zwang, Miinchen/Berlin: R. Oldenbourg 1928. [6] WEBER, C., and W. GUNTHER: Torsionstheorie, Braunschweig: Vieweg 1958. [7] TIMOSHENKO, S.: Einige Stabilitatsprobleme der Elastizitatstheorie. Z. Math. Phys. 58 (1910). [8] BACH, C. VON: Versuche iiber die tatsachliche Widerstandsfahigkeit von Balken mit [-fOrmigem Querschnitt. Z. VDI 1909, 1910. [9] MAILLART, R.: Zur Frage der Biegung. Schweiz. Bauztg. 77 (1921) 195. [10] EGGENSCHWYLER, A.: tiber die Festigkeitsberechnung von Schiebetoren und ahnlichen Bauwerken. Diss. E.T.H., 1921, Borna bei Leipzig: Robert Noske [11] WAGNER, H.: Verdrehung und Knickung von offenen Profilen. Festschrift 25 Jahre T.H. Danzig, 1929, or Luftf.-Forschg. 11 (1934) 329. [12] KAPPUS, R.: Drillknicken zentrisch gedriickter Stabe mit offenem Profil im elastischen Bereich. Luftf.-Forschg. 13 (1937) 444. [13] BORNSCHEUER, F.W.: Systematische Darstellung des Biege- und Verdrehvorganges unter besonderer Beriicksichtigung der W6lbkrafttorsion. Stahlbau 21 (1952) 1. (14) WANSLEBEN, F.: Die Theorie der Drillfestigkeit von Stahlbauteilen, K6ln: Stahlbau Verlag 1956. [15] HEILIG, R.: Der SchubverformungseinfluB auf die W6lbkrafttorsion von Staben mit offenem Profil. Stahlbau 30 (1961) 67. [16] GOODIER, J.N.: The Buckling of Compressed Bars by Torsion and Flexure. Cornell University, Engineering Experiment Station, Bulletin 27, 1941.
In 1978, the European Mechanics Committee and the French Centre National de la Recherche Scientifique agreed to the organization of an Interna tional Colloquium on the "Mechanical Behavior of Anisotropic Solids". The meeting was held at Villard-de-Lans (near Grenoble, France) from 19th to 22 nd June 1979. The Colloquium considered mechanical aspects of the anisotropy of solids, both initial and induced by permanent deformation, anisotropic hardening and damage, oriented fissuration, etc. Topics concerned mathematical, experimental and engineering aspects of the anisotropy of metals, composites, soils and rocks. The aim of the Colloquium was to bring together experimentalists, theoretecians and engineers interested in various features of mechanical anisotropy, in order to permit an interdisciplinary exchange of understanding, experience and methods. A detailed description of the scope, aim and proposed topics is contained in the Preface. The announcement of the Colloquium attracted a large number of sub mitted contributions. Conforming with the principles of Euromech Colloquia and of the Colloques Internationaux du CNRS, the accepted contributions were limited to 50 communications. A general description of the scientific program is to be found in the Preface. Five general lectures gave state-of-the-art reports concerning some areas of the behavior of anisotropic solids; the 50 communications were divided into 12 sessions dealing with specific topics (see "Contents"). In order to facilitate subsequent contact between the reader and the contributors, full addresses are given in the "List of Authors."
This volume contains the written texts of the papers presented at a Symposium on Buckling of Structures held at Harvard University in June 1974. This symposium, one of several on various topics sponsored annually by the International Union of Theoretical and Applied Me chanics (IUTAM), was organized by a Scientific Committee consisting of B. Budiansky (Chairman), A. H. Chilver, W. T. Koiter, and A. S. Vol' mir. Participation was by invitation of the Scientific Committee, and specific lecturers were invited to speak in the areas of experimental research, buckling and post-buckling calculations, post-buckling mode interaction, plasticity and creep effects, dynamic buckling, stochastic problems, and design. A total of 29 lectures were delivered, including a general opening lecture by Professor Koiter, and there were 93 reg istered participants from 16 different countries. Financial support for the symposium was provided by IUTAM, in the form of partial travel support for a number of participants, and also by the National Science Foundation, the National Aeronautics and Space Administration, and the Air Force Office of Scientific Re search, for additional travel support and administrative expenses. Meeting facilities and services were efficiently provided by the Science Center of Harvard University, and administrative support was gen erously provided by the Division of Engineering and Applied Physics of Harvard University. The scientific chairman enjoyed the invaluable assistance of his colleagues Professors J. W. Hutchinson and J. L.
This book was written to serve as the standard textbook of elastoplasticity for students, engineers and researchers in the field of applied mechanics. The present second edition is improved thoroughly from the first edition by selecting the standard theories from various formulations and models, which are required to study the essentials of elastoplasticity steadily and effectively and will remain universally in the history of elastoplasticity. It opens with an explanation of vector-tensor analysis and continuum mechanics as a foundation to study elastoplasticity theory, extending over various strain and stress tensors and their rates. Subsequently, constitutive equations of elastoplastic and viscoplastic deformations for monotonic, cyclic and non-proportional loading behavior in a general rate and their applications to metals and soils are described in detail, and constitutive equations of friction behavior between solids and its application to the prediction of stick-slip phenomena are delineated. In addition, the return-mapping algorithm, the consistent tangent operators and the objective time-integration algorithm of rate tensor are explained in order to enforce the FEM analyses. All the derivation processes and formulations of equations are described in detail without an abbreviation throughout the book.

The distinguishable features and importance of this book is the comprehensive description of fundamental concepts and formulations including the objectivity of

tensor and constitutive equations, the objective time-derivative of tensor functions, the associated flow rule, the loading criterion, the continuity and smoothness conditions and their substantial physical interpretations in addition to the wide classes of reversible/irreversible constitutive equations of solids and friction behavior between solids.

This book collects the theoretical derivation of a recently presented general variational macroscopic continuum theory of multiphase poroelasticity (VMTPM), together with its applications to consolidation and stress partitioning problems of interest in several applicative engineering contexts, such as in geomechanics and biomechanics.

The theory is derived based on a purely-variational deduction, rooted in the least-Action principle, by considering a minimal set of kinematic descriptors. The treatment herein considered keeps a specific focus on the derivation of most general medium-independent governing equations.

It is shown that VMTPM recovers paradigms of consolidated use in multiphase poroelasticity such as Terzaghi's stress partitioning principle and Biot's equations for wave propagation. In particular, the variational treatment permits the derivation of a general medium-independent stress partitioning law, and the proposed variational theory predicts that the external stress, the fluid pressure, and the stress tensor work-associated with the macroscopic strain of the solid phase are partitioned according to a relation which, from a formal point of view, turns out to be strictly compliant with Terzaghi's law, irrespective of the microstructural and constitutive features of a given medium. Moreover, it is shown that some experimental observations on saturated sandstones, generally considered as proof of deviations from Terzaghi's law, are ordinarily predicted by VMTPM.

As a peculiar prediction of VMTPM, the book shows that the phenomenon of compression-induced liquefaction experimentally observed in cohesionless mixtures can be obtained as a natural implication of this theory by a purely rational deduction. A characterization of the phenomenon of crack closure in fractured media is also inferred in terms of macroscopic strain and stress paths.

Altogether the results reported in this monograph exemplify the capability of VMTPM to describe and predict a large class of linear and nonlinear mechanical behaviors observed in two-phase saturated materials.

THE FOUNDATIONS OF THERMOELASTICITY-EXPERIMENTS AND THEORY (A. PHILLIPS) 1. Introduction 2. The initial yield surface 4 3. The subsequent yield surface 6 4. Some theoretical consequences 10 References 13 ON THE PHYSICS AND MATHEMATICS OF SELF-STRESSES (E. KRONER) 1. Introduction 22 2. The physical origin of the self-stresses 23 3. Formulation of the mathematical problem of self-stresses 27 4. The method of modified Green's functions 30 5. Concluding remarks 35 References 38 DISTORTION IN MICROPOLAR ELASTICITY (W. NOWACKI) 1. Fundamental relations and equations 39 2. Principle of virtual work 42 3. Theorem of minimum of the complimentary work 43 • 4. Reciprocity theorem 44 5. Equations in displacements and rotations 47 6. Compatibility equations 51 References 57 THE YIELD CRITERION IN THE GENERAL CASE OF NONHOMOGENEOUS STRESS AND DEFORMATION FIELDS (J. A. KONIG and W. OLSZAK) 1. Introduction 58 2. The plasticity condition 61 3. Special cases of the yield condition 62 4. Example: Pure bending 63 5. Criteria for neutral, passive and active processes 65 VI 6. The flow law 67 References 69 ELECTRO-MAGNETO-ELASTICITY (J. B. ALBLAS) 1. Introduction 71 2. Balance equations 77 3. The jump and boundary conditions 85 4. The constitutive equations 91 5. Linearization of the magnetic problem 95 6. Magneto-elastic waves in the infinite space and in the half-space 105 References 114 PLASTICITY AND CREEP THEORY IN ENGINEERING MECHANICS (J. F • BESSE LING) 1. Introduction 115 2. Limit analysis 117 3.
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