scholarly journals The Rules for the Lattice Rotation Accompanying Slip as Derived From a Self-Consistent Model

1999 ◽  
Vol 31 (4) ◽  
pp. 217-230 ◽  
Author(s):  
R. A. Lebensohn ◽  
T. Leffers
Keyword(s):  
Solid Mechanics ◽  
Grain Shape ◽  
Rolling Plane ◽  
Lattice Rotation ◽  
Consistent Model ◽  
Plane Strain Deformation ◽  
Self Consistent ◽  
The One ◽  
Equiaxed Grains ◽  
Very High

The rules for the lattice rotation during rolling (plane strain) deformation of fcc polycrystals are studied with a viscoplastic self-consistent model. Very high values of the ratesensitivity exponent are used in order to establish Sachs-type conditions with large local deviations from the macroscopic strain. The lattice rotation depends on the grain shape. For equiaxed grains the lattice rotation follows the MA rule, which is the one normally used in solid mechanics. For elongated and flat grains the lattice rotation follows a different rule, the PSA rule. In the standard version the model performs a transition from MA to PSA with increasing strain. There is avery clear difference between the textures resulting from the two different rules. MA leads to a copper-type texture, and PSA leads to a brass-type texture.

Elastic Property Estimation in Polycrystalline Films with Crystallographic Texture and Grain Shape

1995 ◽  
Vol 403 ◽  
Author(s):  
B. C. Hendrix ◽  
L. G. Yu ◽  
K. W. Xu ◽  
J. W. He
Keyword(s):  
Thin Films ◽  
Elastic Constants ◽  
Crystallographic Texture ◽  
Grain Shape ◽  
Elastic Anisotropy ◽  
Polycrystalline Films ◽  
Property Estimation ◽  
Bulge Testing ◽  
Consistent Model ◽  
Self Consistent

AbstractAlthough methods of measuring the elastic properties of thin films have made great advances with the use of bulge testing of membranes, deflection of micromachined beams, and nanoindentation, most results are still being compared to either isotropic or single crystal elastic constants, neither of which are, in general, appropriate for textured polycrystalline films. This paper uses recent results of a self-consistent model (after Krbner and Kneer) which calculates the elastic anisotropy arising from crystallographic texture and which has been extended to predict the anisotropy resulting from grain shape. These results are compared to the various Voigt, Reuss, and Hill approximations that are appropriate for different crystallographic textures. The accuracies of the different models are evaluated in terms of their ability to predict the biaxial modulus and indentation compliance that are most commonly measured in thin films.

Texture and High-Angle Boundary Formation during Deformation Processing

2008 ◽  
Vol 604-605 ◽  
pp. 251-258
Author(s):  
Terry R. McNelley ◽  
S. Swaminathan ◽  
J.Q. Su ◽  
Alex P. Zhilyaev
Keyword(s):  
Pure Aluminum ◽  
High Angle Boundary ◽  
The Other ◽  
Lattice Rotation ◽  
High Angle ◽  
Deformation Bands ◽  
Deformation Processing ◽  
Angular Pressing ◽  
Plane Strain Deformation ◽  
Equiaxed Grains

Among the phenomena leading to formation of high-angle boundaries during deformation processing at low homologous temperatures is the subdivision of prior grains and formation of deformation bands. Evidence for this phenomenon during processing of AA2004, a superplastic aluminum alloy, is reviewed; fragmentation of deformation bands leads to equiaxed grains and high-angle boundaries that support superplasticity. In addition to subdivision, groups of grains undergo lattice rotation toward one or the other variant of the β orientation fibers during plane-strain deformation of pure aluminum by ambient temperature rolling. The formation of equiaxed grains from banded structures during simple shear by equal channel angular pressing (ECAP) is also considered.

Modeling of the Grain Shape Effect on the Elastic-Inelastic Behavior of Polycrystals With Self-Consistent Scheme

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
A. Abdul-Latif ◽  
M. Radi
Keyword(s):  
Grain Shape ◽  
Spherical Inclusion ◽  
Shape Effect ◽  
Inelastic Behavior ◽  
Consistent Model ◽  
Self Consistent ◽  
Eshelby’S Tensor ◽  
Anisotropic Elastic ◽  
Nonlinear Elastic ◽  
Interaction Law

Based on a well established nonincremental interaction law for fully anisotropic elastic-inelastic behavior of polycrystals, tangent formulation-based and simplified interaction laws of softened nature are derived to describe the nonlinear elastic-inelastic behavior of fcc polycrystals. Using the Eshelby’s tensor, the developed approach considers that the inclusion (grain) form is ellipsoidal. It has been clearly demonstrated by Abdul-Latif et al. (2002, “Elastic-Inelastic Self-Consistent Model for Polycrystals,” ASME J. Appl. Mech., 69, pp. 309–316) for spherical inclusion that the tangent formulation-based model requires more calculation time, and is incapable to describe correctly the multiaxial elastic-inelastic behavior of polycrystals in comparison with the simplified model. Hence, the simplified nonincremental interaction is studied considering the grain shape effect. A parametric study is conducted showing principally the influence of the some important parameters (the grain shape (α) and the new viscous parameter γ) and the effect of their interaction on the hardening evolution of polycrystals. Quantitatively, it is recognized that the model describes suitably the grain shape effect together with the new viscous parameter γ on the strain-stress behavior of aluminum and Waspaloy under tensile test.

THEORY AND SELF-CONSISTENT MODEL OF DUST-DRIVEN WINDS

2002 ◽  
Vol 5 ◽  
pp. 65-65
Author(s):  
S. Liberatore ◽  
J.-P.J. Lafon ◽  
N. Berruyer
Keyword(s):  
Consistent Model ◽  
Self Consistent

Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta
Keyword(s):  
Removal Rate ◽  
Removal Rates ◽  
Carbon Removal ◽  
Biofilm Growth ◽  
Loading Rates ◽  
Biomass Activity ◽  
High Turbulence ◽  
The One ◽  
High Level ◽  
Very High

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.

scholarly journals Stellar Flares: Observations and Theory

1989 ◽  
Vol 104 (2) ◽  
pp. 49-52
Author(s):  
Suzanne L. Hawley
Keyword(s):  
Scaling Law ◽  
Dynamic Scaling ◽  
X Ray ◽  
Temperature Distributions ◽  
Photometric And Spectroscopic Observations ◽  
Stellar Flares ◽  
Consistent Model ◽  
Self Consistent ◽  
Flare Model ◽  
Large Flare

AbstractPhotometric and spectroscopic observations of a very large flare on AD Leo are presented. A self consistent model of a flare corona, transition region and chromosphere is developed; in particular the chromospheric temperature distributions resulting from X-ray and EUV irradiation by coronae of various temperatures are determined. The predicted line fluxes in Hγ are compared to the observed line fluxes to find the coronal temperature as a function of time during the flare. This run of temperature with time is then compared with the predictions of an independent theoretical flare model based on a dynamic scaling law (see paper by Fisher and Hawley, these proceedings).

scholarly journals A Self‐Consistent Model for Sorption and Transport in Polyimide‐Derived Carbon Molecular Sieve Gas Separation Membranes

2020 ◽  
Vol 132 (46) ◽  
pp. 20523-20527
Author(s):  
Oishi Sanyal ◽  
Samuel S. Hays ◽  
Nicholas E. León ◽  
Yoseph A. Guta ◽  
Arun K. Itta ◽  
...  
Keyword(s):  
Gas Separation ◽  
Molecular Sieve ◽  
Carbon Molecular Sieve ◽  
Separation Membranes ◽  
Gas Separation Membranes ◽  
Consistent Model ◽  
Self Consistent

scholarly journals Self-consistent model for ambipolar tunnelling in quantum-well systems

1995 ◽  
Vol 10 (5) ◽  
pp. 577-585 ◽  
Author(s):  
C Presilla ◽  
V Emiliani ◽  
A Frova
Keyword(s):  
Quantum Well ◽  
Consistent Model ◽  
Self Consistent

Many-body Green functions in nuclear physics

2017 ◽  
Vol 26 (01n02) ◽  
pp. 1740025 ◽  
Author(s):  
J. Speth ◽  
N. Lyutorovich
Keyword(s):  
Nuclear Physics ◽  
Green Functions ◽  
Many Body ◽  
General Applicability ◽  
Pair Correlations ◽  
Self Consistent ◽  
The Many ◽  
The One ◽  
General Relations ◽  
Three Body

Many-body Green functions are a very efficient formulation of the many-body problem. We review the application of this method to nuclear physics problems. The formulas which can be derived are of general applicability, e.g., in self-consistent as well as in nonself-consistent calculations. With the help of the Landau renormalization, one obtains relations without any approximations. This allows to apply conservation laws which lead to important general relations. We investigate the one-body and two-body Green functions as well as the three-body Green function and discuss their connection to nuclear observables. The generalization to systems with pair correlations are also presented. Numerical examples are compared with experimental data.

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