[PDF] Mechanics Of Strain Gradient Materials eBook

Author : Albrecht Bertram
Publisher : Springer Nature
Page : 177 pages
File Size : 38,14 MB
Release : 2020-06-30
Category : Science
ISBN : 3030438309

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Over the past 50 years, strain gradient material theories have been developed for the continuum modeling of size effects in materials and structures in terms of their elasticity, plasticity and fracturing. This book puts forward a unifying perspective to combine existing theories involving the higher order gradient of the strain tensor, or of plastic strain. It begins by reviewing experimental findings on the existence (or non-existence) of size effects on the mechanics of materials. In turn, the book devises first, second and higher order strain gradient theories from general principles, and presents constitutive frameworks that satisfy thermodynamic requirements. The special case of strain gradient plasticity is then developed and illustrated via computational analyses of size effects on the plasticity of metals at small scales. In closing, the book explains the origin of gradient effects in the case of lattice structures by drawing on homogenization theory.

Author : Holm Altenbach
Publisher : Springer Nature
Page : 231 pages
File Size : 14,53 MB
Release : 2019-11-04
Category : Technology & Engineering
ISBN : 303030406X

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This book discusses recent findings and advanced theories presented at two workshops at TU Berlin in 2017 and 2018. It underlines several advantages of generalized continuum models compared to the classical Cauchy continuum, which although widely used in engineering practice, has a number of limitations, such as: • The structural size is very small. • The microstructure is complex. • The effects are localized. As such, the development of generalized continuum models is helpful and results in a better description of the behavior of structures or materials. At the same time, there are more and more experimental studies supporting the new models because the number of material parameters is higher.

Author : Emilio Martínez Pañeda
Publisher : Springer
Page : 166 pages
File Size : 42,9 MB
Release : 2017-08-23
Category : Science
ISBN : 3319633848

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This book provides a comprehensive introduction to numerical modeling of size effects in metal plasticity. The main classes of strain gradient plasticity formulations are described and efficiently implemented in the context of the finite element method. A robust numerical framework is presented and employed to investigate the role of strain gradients on structural integrity assessment. The results obtained reveal the need of incorporating the influence on geometrically necessary dislocations in the modeling of various damage mechanisms. Large gradients of plastic strain increase dislocation density, promoting strain hardening and elevating crack tip stresses. This stress elevation is quantified under both infinitesimal and finite deformation theories, rationalizing the experimental observation of cleavage fracture in the presence of significant plastic flow. Gradient-enhanced modeling of crack growth resistance, hydrogen diffusion and environmentally assisted cracking highlighted the relevance of an appropriate characterization of the mechanical response at the small scales involved in crack tip deformation. Particularly promising predictions are attained in the field of hydrogen embrittlement. The research has been conducted at the Universities of Cambridge, Oviedo, Luxembourg, and the Technical University of Denmark, in a collaborative effort to understand, model and optimize the mechanical response of engineering materials.

Author : Albrecht Bertram
Publisher : Springer Nature
Page : 307 pages
File Size : 25,4 MB
Release : 2022-05-28
Category : Technology & Engineering
ISBN : 3031045009

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This book offers frameworks for the material modeling of gradient materials both for finite and small deformations within elasticity, plasticity, viscosity, and thermomechanics. The first chapter focuses on balance laws and holds for all gradient materials. The next chapters are dedicated to the material modeling of second and third-order materials under finite deformations. Afterwards the scope is limited to the geometrically linear theory, i.e., to small deformations. The next chapter offers an extension of the concept of internal constraints to gradient materials. The final chapter is dedicated to incompressible viscous gradient fluids with the intention to describe, among other applications, turbulent flows, as already suggested by Saint-Venant in the middle of the 19th century.

Author : Vadim V. Silberschmidt
Publisher : Springer
Page : 205 pages
File Size : 20,86 MB
Release : 2015-04-09
Category : Technology & Engineering
ISBN : 3319171186

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The book presents interesting examples of recent developments in this area. Among the studied materials are bulk metallic glasses, metamaterials, special composites, piezoelectric smart structures, nonwovens, etc. The last decades have seen a large extension of types of materials employed in various applications. In many cases these materials demonstrate mechanical properties and performance that vary significantly from those of their traditional counterparts. Such uniqueness is sought – or even specially manufactured – to meet increased requirements on modern components and structures related to their specific use. As a result, mechanical behaviors of these materials under different loading and environmental conditions are outside the boundaries of traditional mechanics of materials, presupposing development of new characterization techniques, theoretical descriptions and numerical tools. The book presents interesting examples of recent developments in this area. Among the studied materials are bulk metallic glasses, metamaterials, special composites, piezoelectric smart structures, nonwovens, etc.

Author : Frederick D. Day
Publisher :
Page : 84 pages
File Size : 43,79 MB
Release : 1966
Category :
ISBN :

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An analytic solution is obtained for two composite-body problems employing the strain-gradient theory of elasticity as developed by Mindlin. The investigation is concerned with the effects produced by strain-gradients, especially bonding stresses in the vicinity of an interface separating two dissimilar materials when higher order contact conditions prevail at the common boundary. The composite body under consideration consists of an infinite elastic strip ('microlayer') embedded in two semi-infinite elastic regions. The first problem concerns the case of uniform tension at infinity applied in a direction perpendicular to the microlayer. The second considers simple shear applied at infinity parallel to the microlayer. It is shown that the stresses that develop in the vicinity of an interface may be at large variance with the classical results. The magnitude of these stresses may be many times greater than the classical values, thus emphasizing the uncertainty of the classical approach in this instance. This variance is very significant when one material is much more rigid than the other, as encountered in the practical case of composite materials.

Author : Zhuo Zhuang
Publisher : Academic Press
Page : 450 pages
File Size : 34,85 MB
Release : 2019-04-12
Category : Technology & Engineering
ISBN : 0128145927

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Dislocation Based Crystal Plasticity: Theory and Computation at Micron and Submicron Scale provides a comprehensive introduction to the continuum and discreteness dislocation mechanism-based theories and computational methods of crystal plasticity at the micron and submicron scale. Sections cover the fundamental concept of conventional crystal plasticity theory at the macro-scale without size effect, strain gradient crystal plasticity theory based on Taylar law dislocation, mechanism at the mesoscale, phase-field theory of crystal plasticity, computation at the submicron scale, including single crystal plasticity theory, and the discrete-continuous model of crystal plasticity with three-dimensional discrete dislocation dynamics coupling finite element method (DDD-FEM). Three kinds of plastic deformation mechanisms for submicron pillars are systematically presented. Further sections discuss dislocation nucleation and starvation at high strain rate and temperature effect for dislocation annihilation mechanism. Covers dislocation mechanism-based crystal plasticity theory and computation at the micron and submicron scale Presents crystal plasticity theory without size effect Deals with the 3D discrete-continuous (3D DCM) theoretic and computational model of crystal plasticity with 3D discrete dislocation dynamics (3D DDD) coupling finite element method (FEM) Includes discrete dislocation mechanism-based theory and computation at the submicron scale with single arm source, coating micropillar, lower cyclic loading pillars, and dislocation starvation at the submicron scale

Author : Peter Haupt
Publisher : Springer Science & Business Media
Page : 666 pages
File Size : 37,93 MB
Release : 2013-03-14
Category : Technology & Engineering
ISBN : 3662047756

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The new edition includes additional analytical methods in the classical theory of viscoelasticity. This leads to a new theory of finite linear viscoelasticity of incompressible isotropic materials. Anisotropic viscoplasticity is completely reformulated and extended to a general constitutive theory that covers crystal plasticity as a special case.

Author : Francesco dell'Isola
Publisher : Springer Nature
Page : 403 pages
File Size : 29,35 MB
Release : 2020-11-01
Category : Science
ISBN : 3030537552

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This book reviews the mathematical modeling and experimental study of systems involving two or more different length scales. The effects of phenomena occurring at the lower length scales on the behavior at higher scales are of intrinsic scientific interest, but can also be very effectively used to determine the behavior at higher length scales or at the macro-level. Efforts to exploit this micro- and macro-coupling are, naturally, being pursued with regard to every aspect of mechanical phenomena. This book focuses on the changes imposed on the dynamics, strength of materials and durability of mechanical systems by related multiscale phenomena. In particular, it addresses: 1: the impacts of effective dissipation due to kinetic energy trapped at lower scales 2: wave propagation in generalized continua 3: nonlinear phenomena in metamaterials 4: the formalization of more general models to describe the exotic behavior of meta-materials 5: the design and study of microstructures aimed at increasing the toughness and durability of novel materials