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Journal ArticleDOI

Structural changes and viscoplastic behavior of a generic embedded-atom model metal in steady shear flow

27 Feb 2004-Physical Review E (American Physical Society)-Vol. 69, Iss: 2, pp 021509-021509
TL;DR: The "common neighbor analysis," based on planar graphs is used to obtain information about the transient structures accompanying viscoplastic behavior on an atomic level, and a simple analytical expression for the isotropic pressure at finite temperatures is proposed.
Abstract: We study equilibrium and nonequilibrium properties of a simple ``generic embedded-atom model'' (GEAM) for metals. The model allows to derive simple analytical expressions for several zero-temperature constitutive properties---in overall agreement with real metals. The model metal is then subjected to shear deformation and strong flow via nonequilibrium molecular dynamics simulation in order to discuss the origins of some qualitative properties observed using more specific embedded-atom potentials. The ``common neighbor analysis,'' based on planar graphs is used to obtain information about the transient structures accompanying viscoplastic behavior on an atomic level. In particular, pressure tensor components and plastic yield are investigated and correlated with underlying structural changes. A simple analytical expression for the isotropic pressure at finite temperatures is proposed. A nonequilibrium phase diagram is obtained by semianalytic calculation.

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Citations
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Journal ArticleDOI
TL;DR: The atomistic response of a model amorphous material submitted to plastic shear in the athermal, quasi-static limit is analyzed in detail, showing a hyper-diffusive regime followed by a diffusive regime, even at zero temperature.
Abstract: We analyze in detail the atomistic response of a model amorphous material submitted to plastic shear in the athermal, quasi-static limit. After a linear stress-strain behavior, the system undergoes a noisy plastic flow. We show that the plastic flow is spatially heterogeneous. Two kinds of plastic events occur in the system: quadrupolar localized rearrangements, and shear bands. The analysis of the individual motion of a particle shows also two regimes: a hyper-diffusive regime followed by a diffusive regime, even at zero temperature.

206 citations

Journal ArticleDOI
TL;DR: It is shown that the widely used exponential-6 and Born-Mayer-Huggins alkali halide potentials produce many-particle systems that are thermodynamically unstable.
Abstract: We apply the pair interaction stability criteria of Fisher and Ruelle (1966 J. Math. Phys. 7 260) to establish the range of thermodynamic stability for a number of simple analytic potential forms used for condensed matter theory and modelling in the literature. We identify the ranges of potential parameters where, for a given potential, the system is thermodynamically stable, unstable and of uncertain stability. This was further explored by carrying out molecular dynamics simulations on the double Gaussian potential in the stable and unstable regimes. We show that, for example, the widely used exponential-6 and Born–Mayer–Huggins alkali halide potentials produce many-particle systems that are thermodynamically unstable.

21 citations

Journal ArticleDOI
TL;DR: In this paper, a coarse grain molecular dynamics description of an ionic liquid as a lubricant which can expand into lateral reservoirs was implemented for simulating meso-scopic phenomena related to lubrication of the piston ring-cylinder liner contact, and two regimes of lubrication, an elasto-hydrodynamic one under low loads and one with low, velocity-independent specific friction, under high loads.

19 citations


Cites background from "Structural changes and viscoplastic..."

  • ...Such schemes have been employed extensively for modelling a wide range of systems including metals [29] and metal-metal oxide interfaces [30]....

    [...]

  • ...Computationally efficient many–body potentials such as embedded atom method (EAM) potential [28,29] can be applied for the description of such solids....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the influence of grain boundaries on electronic properties of polycrystalline organic semiconductor naphthalene was investigated using a Monte Carlo method, whereas electronic structure calculations were performed using the charge patching method.
Abstract: We investigated the influence of grain boundaries on electronic properties of polycrystalline organic semiconductor naphthalene. The atomic structure of grain boundaries was found using a Monte Carlo method, whereas electronic structure calculations were performed using the charge patching method. We found that grain boundaries introduce trap states within the band gap of the material. Our results show that spatial positions and energies of trap states can be predicted solely from geometrical arrangement of molecules near the boundary. Wave functions of these states are localized on closely spaced pairs of molecules from opposite sides of the boundary. The energies of trap states are strongly correlated with the distances between the molecules in the pair. These findings were used to calculate the electronic density of trap states, which was found to exhibit a qualitatively different behavior for grain boundaries perpendicular to the a and b directions of the crystal unit cell.

19 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the question of whether fluids and crystals are differentiated on the basis of their zero frequency shear moduli or their limiting zero-frequency shear viscosity.
Abstract: We examine the question of whether fluids and crystals are differentiated on the basis of their zero frequency shear moduli or their limiting zero frequency shear viscosity. We show that while fluids, in contrast with crystals, do have a zero value for their shear modulus, in contradiction to a widespread presumption, a crystal does not have an infinite or exceedingly large value for its limiting zero frequency shear viscosity. In fact, while the limiting shear viscosity of a crystal is much larger than that of the liquid from which it is formed, its viscosity is much less than that of the corresponding glass that may form assuming the liquid is a good enough glass former.

17 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the authors derived an expression for the total energy of a metal using the embedding energy from which they obtained several ground-state properties, such as the lattice constant, elastic constants, sublimation energy, and vacancy-formation energy.
Abstract: We develop the embedded-atom method [Phys. Rev. Lett. 50, 1285 (1983)], based on density-functional theory, as a new means of calculating ground-state properties of realistic metal systems. We derive an expression for the total energy of a metal using the embedding energy from which we obtain several ground-state properties, such as the lattice constant, elastic constants, sublimation energy, and vacancy-formation energy. We obtain the embedding energy and accompanying pair potentials semiempirically for Ni and Pd, and use these to treat several problems: surface energy and relaxation of the (100), (110), and (111) faces; properties of H in bulk metal (H migration, binding of H to vacancies, and lattice expansion in the hydride phase); binding site and adsorption energy of hydrogen on (100), (110), and (111) surfaces; and lastly, fracture of Ni and the effects of hydrogen on the fracture. We emphasize problems with hydrogen and with surfaces because none of these can be treated with pair potentials. The agreement with experiment, the applicability to practical problems, and the simplicity of the technique make it an effective tool for atomistic studies of defects in metals.

5,912 citations

Book
01 Jan 1954
TL;DR: Tabor and Bowden as mentioned in this paper reviewed the many advances made in this field during the past 36 years and outlined the achievements of Frank Philip Bowden, and reviewed the behavior of non-metals, especially elastomers; elastohydrodynamic lubrication; and the wear of sliding surfaces.
Abstract: Originally published in 1950, this classic book was a landmark in the development of the subject of tribology. For this edition, David Tabor has written a new preface, reviewing the many advances made in this field during the past 36 years and outlining the achievements of Frank Philip Bowden. The book covers the behavior of non-metals, especially elastomers; elastohydrodynamic lubrication; and the wear of sliding surfaces, which has gradually replaced the earlier concentration on the mechanism of friction. It remains one of the most interesting and comprehensive works available on a single branch of physics.

5,834 citations

Journal ArticleDOI
TL;DR: In this paper, the theory and application of Smoothed particle hydrodynamics (SPH) since its inception in 1977 are discussed, focusing on the strengths and weaknesses, the analogy with particle dynamics and the numerous areas where SPH has been successfully applied.
Abstract: In this review the theory and application of Smoothed particle hydrodynamics (SPH) since its inception in 1977 are discussed. Emphasis is placed on the strengths and weaknesses, the analogy with particle dynamics and the numerous areas where SPH has been successfully applied.

3,623 citations

Journal ArticleDOI
TL;DR: In this article, a semi-empirical model of metals and impurities (embedded atom method) was proposed to make possible a static treatment of the brittle fracture of a transition metal in the presence of hydrogen.
Abstract: A new, semiempirical model of metals and impurities (embedded atom method) makes possible a static treatment of the brittle fracture of a transition metal in the presence of hydrogen. Results indicate that hydrogen can reduce the fracture stress in nickel.

2,274 citations