scholarly journals Concurrent multiscale modeling of microstructural effects on localization behavior in finite deformation solid mechanics

2017 ◽  
Vol 61 (1-2) ◽  
pp. 207-218 ◽  
Author(s):  
Coleman N. Alleman ◽  
James W. Foulk ◽  
Alejandro Mota ◽  
Hojun Lim ◽  
David J. Littlewood
10.1142/p604 ◽  
2009 ◽  
Author(s):  
Ugo Galvanetto ◽  
M H Ferri Aliabadi

1994 ◽  
Vol 47 (6) ◽  
pp. 171-205 ◽  
Author(s):  
Yoshihiro Tomita

The purpose of the present article is provide a perspective for computational predictions related to such plastic instabilities as buckling, necking and flow localization including shear–banding under a wide range of deformation rates for a variety of materials, including single– and polycrystals. Computational bifurcation analyses for general cases, axisymmetric to nonaxisymmetric deformation, very thin–walled bodies, and specific materials with nonstandard constitutive equations are given. The postbifurcation analyses and regularization schemes to remedy the problems associated with spurious mesh sensitivity and incorrect convergence in finite element prediction of flow localization behavior are discussed. The instability behavior of thick circular tubes deformed under pressure and combined loading of internal/external pressure and axial force, neck and bulge propagations in polymeric materials, wrinkling of thin plates and shells under sheet metal forming processes, flow localization of thermo–elasto–viscoplastic materials under a wide range of deformation rates including adiabatic shear banding, and flow localization behavior of mono– and polycrystalline solids are reviewed with illustrative examples.


Author(s):  
W. R. Duff ◽  
L. E. Thomas ◽  
R. M. Fisher ◽  
S. V. Radcliffe

Successful retrieval of the television camera and other components from the Surveyor III spacecraft by the Apollo 12 astronauts has provided a unique opportunity to study the effects of a known and relatively extensive exposure to the lunar environment. Microstructural effects including those produced by micro-meteorite impact, radiation damage (by both the solar wind and cosmic rays) and solar heating might be expected in the materials used to fabricate the spacecraft. Samples received were in the form of 1 cm2 of painted unpainted aluminum alloy sheet from the top of the camera visor (JPL Code 933) and the sides (935,936) and bottom (934) of the lower camera shroud. They were prepared for transmission electron microscopy by first hand-grinding with abrasive paper to a thickness of 0.006". The edges were lacquered and the sample electropolished in 10% perchloric methanol using the “window” method, to a thickness of ~0.001". Final thinning was accomplished by polishing 3 mm punched disks in an acetic-phosphoric-nitric acid solution.


Author(s):  
R.L. Sabatini ◽  
Yimei Zhu ◽  
Masaki Suenaga ◽  
A.R. Moodenbaugh

Low temperature annealing (<400°C) of YBa2Cu3O7x in a ozone containing oxygen atmosphere is sometimes carried out to oxygenate oxygen deficient thin films. Also, this technique can be used to fully oxygenate thinned TEM specimens when oxygen depletion in thin regions is suspected. However, the effects on the microstructure nor the extent of oxygenation of specimens has not been documented for specimens exposed to an ozone atmosphere. A particular concern is the fact that the ozone gas is so reactive and the oxygen diffusion rate at these temperatures is so slow that it may damage the specimen by an over-reaction. Thus we report here the results of an investigation on the microstructural effects of exposing a thinned YBa2Cu3O7-x specimen in an ozone atmosphere using transmission electron microscopy and energy loss spectroscopy techniques.


Author(s):  
Peter Howell ◽  
Gregory Kozyreff ◽  
John Ockendon
Keyword(s):  

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