Modeling Internal Stresses in the Nonelastic Deformation of Metals

1986 ◽  
Vol 108 (4) ◽  
pp. 365-373 ◽  
Author(s):  
T. C. Lowe ◽  
A. K. Miller
Keyword(s):  
Experimental Data ◽  
Long Range ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Short Range ◽  
Dynamic Recovery ◽  
Small Strain ◽  
Internal Stresses ◽  
Deformation Model

The roles of short range and long range internal stresses during nonelastic deformation have been postulated and explored using the MATMOD-4V deformation model. New microstructural variables have been introduced in MATMOD-4V which represent the effects of internal stresses upon deformation. Simulations for aluminum have been performed to demonstrate improved capability to represent small strain deformation behavior and dynamic recovery. Comparisons are made between experimental data and computer predictions of microplastic straining and cyclic deformation.

Lattice dynamics of ionic molecular crystals in the rigid ion approximation, phases II and III of sodium superoxide

1984 ◽  
Vol 62 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Pier Francesco Fracassi ◽  
Michael L. Klein ◽  
Raffaele Guido Della Valle
Keyword(s):  
Experimental Data ◽  
Computer Program ◽  
Long Range ◽  
Lattice Dynamics ◽  
Short Range ◽  
Molecular Crystals ◽  
Electrostatic Potentials ◽  
Wave Method ◽  
Long Wave

Quasi-harmonic lattice dynamics is developed for ionic molecular crystals, within the framework of the rigid ion approximation. Long-range electrostatic potentials as well as short-range atom–atom interactions are discussed, making extensive use of the Ewald long wave method. A computer program based on this theory has been developed, and phonon calculations have been carried out for phases II and III of solid Na+O2−. The calculated quantities are then compared with experimental data.

Local variations of lattice parameter and long-range internal stresses during cyclic deformation of polycrystalline copper

1993 ◽  
Vol 41 (9) ◽  
pp. 2743-2753 ◽  
Author(s):  
H. Biermann ◽  
T. Ungár ◽  
T. Pfannenmüller ◽  
G. Hoffmann ◽  
A. Borbély ◽  
...  
Keyword(s):  
Long Range ◽  
Cyclic Deformation ◽  
Lattice Parameter ◽  
Internal Stresses ◽  
Polycrystalline Copper

Backstress, the Bauschinger Effect and Cyclic Deformation

2008 ◽  
Vol 604-605 ◽  
pp. 39-51 ◽  
Author(s):  
M.E. Kassner ◽  
P. Geantil ◽  
L.E. Levine ◽  
B.C. Larson
Keyword(s):  
Long Range ◽  
Cyclic Deformation ◽  
Bauschinger Effect ◽  
Internal Stresses ◽  
Dislocation Dipole ◽  
Crystalline Materials ◽  
X Ray ◽  
The Past ◽  
Slip Bands ◽  
Persistent Slip Bands

Backstresses or long range internal stresses (LRIS) in the past have been suggested by many to exist in plastically deformed crystalline materials. Elevated stresses can be present in regions of elevated dislocation density or dislocation heterogeneities in the deformed microstructures. The heterogeneities include edge dislocation dipole bundles (veins) and the edge dipole walls of persistent slip bands (PSBs) in cyclically deformed materials and cell and subgrain walls in monotonically deformed materials. The existence of long range internal stress is especially important for the understanding of cyclic deformation and also monotonic deformation. X-ray microbeam diffraction experiments performed by the authors using synchrotron x-ray microbeams determined the elastic strains within the cell interiors. The studies were performed using, oriented, monotonically deformed Cu single crystals. The results demonstrate that small long-range internal stresses are present in cell interiors. These LRIS vary substantially from cell to cell as 0 % to 50 % of the applied stress. The results are related to the Bauschinger effect, often explained in terms of LRIS.

Diffuse scattering and disorder in zirconia

2005 ◽  
Vol 220 (12) ◽  
Author(s):  
Friedrich Frey ◽  
Hans Boysen ◽  
Ines Kaiser-Bischoff
Keyword(s):  
Experimental Data ◽  
Long Range ◽  
Diffuse Scattering ◽  
Short Range ◽  
Theoretical Work ◽  
Tetragonal Type

AbstractDiffuse scattering in zirconia is reviewed mainly for yttria- and calcia-stabilized material. Common general disorder features are explained by rhombohedral-type and/or tetragonal-type short-range and long-range ordered clusters or “domains”. Differences are comparatively discussed on the basis of available experimental data and theoretical work.

Improved Constitutive Equations for Modeling Strain Softening—Part I: Conceptual Development

1984 ◽  
Vol 106 (4) ◽  
pp. 337-342 ◽  
Author(s):  
T. C. Lowe ◽  
A. K. Miller
Keyword(s):  
Constitutive Equations ◽  
Work Hardening ◽  
Short Range ◽  
Conceptual Development ◽  
Strain Softening ◽  
Dynamic Recovery ◽  
Internal Stresses ◽  
Wide Range ◽  
Deformation Behaviors ◽  
Heterogeneous Microstructures

A microstructurally based model of nonelastic deformation is proposed which is capable of predicting strain softening as well as a wide range of other deformation behaviors. The model, an extension of the MATMOD constitutive equations, now includes representations of both short range and long range internal stresses, strengthening due to homogeneous and heterogeneous microstructures, and dynamic recovery. Additional conceptual improvements regarding the interactions between various sources of work hardening and the influence of straining direction upon deformation induced microstructures are also introduced. The physical origins of these extensions, their relationship to strain softening, and their implementation in the new model, MATMOD-4V, are presented.

scholarly journals Effects of Short and Long Range Correlations on the Charge Densities and Radii of Ca Nuclei

2019 ◽  
Vol 7 ◽  
pp. 47
Author(s):  
G. A. Lalazissis ◽  
S. E. Massen
Keyword(s):  
Experimental Data ◽  
Long Range ◽  
Short Range ◽  
Proton Density ◽  
Nuclear Surface ◽  
Combined Effects ◽  
Mean Square ◽  
Long Range Correlations ◽  
Charge Densities ◽  
Short Range Correlations

The experimental data for the charge (proton) density differences of the even Ca nuclei is analyzed by means of a simple phenomenological model where the effects of certain type short and long range correlations have been accounted. Short range correlations are approximated through the Jastrow type correlation function while for long range correlations the fluctuations of the nuclear surface are considered. The analysis shows that the combined effects of these correlations lead to a better description of the experimental charge (proton) density differences. Moreover, the calculated charge mean square radii of the even Ca nuclei exhibit a parabolic behaviour and compare well with the experimental isotope shifts from the laser spectroscopy measurements.

Cyclic Deformation Behavior of a New N+C Alloying Austenitic Manganese Steel

2014 ◽  
Vol 891-892 ◽  
pp. 1621-1626
Author(s):  
Jie Kang ◽  
Fu Cheng Zhang ◽  
Zhi Nan Yang ◽  
Xiao Yan Long
Keyword(s):  
Internal Stress ◽  
Effective Stress ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Short Range ◽  
High Strain ◽  
Cyclic Softening ◽  
Manganese Steel ◽  
Austenitic Manganese Steel ◽  
Austenitic Manganese

The cyclic deformation behavior and fatigue characteristics of a new austenitic manganese steel with composition FeMn18Cr7C0.8N0.2 (wt%) have been explored and analyzed based on the partition of hysteresis loops linked with microstructure by low cycle testing in the total strain amplitudes 0.3% - 1.0%. The new N+C austenitic manganese steel exhibited immediate cyclic softening for small strain amplitude and initial hardening at the onset of fatigue life followed by softening for medium and high strain amplitudes. For low and high strain amplitudes the evolution of internal stress and effective stress partitioned from the hysteresis loop with the prolonged cycles both corresponded to the change in the total stress amplitudes. With the exception of 316LN0.2 austenitic stainless steel, the effective stress and internal stress made a contribution to the cyclic deformation behavior with similar effect. The markedly improved contribution of effective stress in the new N+C austenitic manganese steel was attributed to the enhanced short range order caused by N+C alloying whereas the decreasing of effective stress with the number of cycles was because of this broken short range interaction. TEM observations showed that the significantly increased planar dislocation structures due to the presence of N+C were responsible for the strong tendency to cyclic softening, in association with the decrease of effective stress and internal stress simultaneously. Moreover the fatigue short crack could be observed on the fractured sample surface at high strain amplitude.

scholarly journals Structural basis of long-range to short-range synaptic transition in NHEJ

Nature ◽  
2021 ◽  
Author(s):  
Siyu Chen ◽  
Linda Lee ◽  
Tasmin Naila ◽  
Susan Fishbain ◽  
Annie Wang ◽  
...  
Keyword(s):  
Long Range ◽  
Short Range ◽  
Structural Basis
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