Bauschinger and size effects in thin-film plasticity

Xiang, Yong; Vlassak, Joost J.

doi:10.1016/j.actamat.2006.06.059

Cited by 231 publications

(185 citation statements)

References 37 publications

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“…Indeed, for the same reasons, it has been justified to use J 2 deformation theory solutions in a number of these cases to compare theory and experiment. Apart from an effort to measure the Bauschinger effect under reversed loading in thin films [15], we are unaware of any micron scale experiments carried out to explicitly explore non-proportional straining effects. Thus, at this time, it is not possible to make use of experimental data to settle the issues related to stress continuity and non-proportionality raised in Sect.…”

Section: Strain Gradient Version Of J 2 Flow Theory 2: Higher Order Smentioning

confidence: 99%

Generalizing J 2 flow theory: Fundamental issues in strain gradient plasticity

Hutchinson

2012

Acta Mech Sin

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It has not been a simple matter to obtain a sound extension of the classical J 2 flow theory of plasticity that incorporates a dependence on plastic strain gradients and that is capable of capturing size-dependent behaviour of metals at the micron scale. Two classes of basic extensions of classical J 2 theory have been proposed: one with increments in higher order stresses related to increments of strain gradients and the other characterized by the higher order stresses themselves expressed in terms of increments of strain gradients. The theories proposed by Muhlhaus and Aifantis in 1991 and Fleck and Hutchinson in 2001 are in the first class, and, as formulated, these do not always satisfy thermodynamic requirements on plastic dissipation. On the other hand, theories of the second class proposed by Gudmundson in 2004 and Gurtin and Anand in 2009 have the physical deficiency that the higher order stress quantities can change discontinuously for bodies subject to arbitrarily small load changes. The present paper lays out this background to the quest for a sound phenomenological extension of the rateindependent J 2 flow theory of plasticity to include a dependence on gradients of plastic strain. A modification of the Fleck-Hutchinson formulation that ensures its thermodynamic integrity is presented and contrasted with a comparable formulation of the second class where in the higher order stresses are expressed in terms of the plastic strain rate. Both versions are constructed to reduce to the classical J 2 flow theory of plasticity when the gradients can be neglected and to coincide with the simpler and more readily formulated J 2 deformation theory of gradient plasticity for deformation histories characterized by proportional straining.

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Section: Strain Gradient Version Of J 2 Flow Theory 2: Higher Order Smentioning

confidence: 99%

Generalizing J 2 flow theory: Fundamental issues in strain gradient plasticity

Hutchinson

2012

Acta Mech Sin

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“…GNDs to the CRSS under macroscopically homogeneous deformation modes may be determined with micro-pillar compression tests [3] and thin-film plane-stress bulge tests [15]. First, the sensitivity of numerical results to the material parameters , , , and were studied.…”

Section: Relative Contributions Of Ssds Andmentioning

confidence: 99%

“…In the recent past, a size effect in free-standing thin films under homogeneous uniaxial deformation [14,15] and compression of micron-and nano-sized pillars [3] was reported. Numerical results from a finite-element (FE) implementation of a dislocation mechanics-based plasticity theory, namely, Mesoscopic Field Dislocation Mechanics [16,17] were shown to be in a good qualitative agreement with experimental observation [18].…”

Section: Introductionmentioning

confidence: 99%

Indentation studies in b.c.c. crystals with enhanced model of strain-gradient crystal plasticity

Demiral

Roy

2013

Computational Materials Science

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• This is the author's version of a work that was accepted for publication in the Computational Materials Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at:http://www.sciencedirect.com/science/article/pii/S0927025613004072

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“…1 They tested passivated and unpassivated copper films with a columnar grain structure. In passivated films, a hysteresis cycle was observed during loading, unloading, and reloading.…”

Section: Introductionmentioning

confidence: 99%

Bauschinger effect in unpassivated freestanding thin films

Shishvan

Nicola

Giessen

2010

Journal of Applied Physics

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Two-dimensional ͑2D͒ discrete dislocation plasticity simulations are carried out to investigate the Bauschinger effect ͑BE͒ in freestanding thin films. The BE in plastic flow of polycrystalline materials is generally understood to be caused by inhomogeneous deformation during loading, leading to residual stress upon unloading. This inhomogeneity can be caused by dislocation pile-ups, variations in texture, grain orientations, and grain size. To study the BE, columnar-grained films as well as films with multiple grains across the thickness are considered. The film is modeled in a 2D framework by a unit cell consisting of an array of grains with different orientation. In order to capture the interaction among grains, we motivate and explore the use of an affine deformation assumption on the grain level to mimic the three-dimensional geometry in this framework. It is shown that the dispersion of grain size in a film together with the size-dependence of yield strength leads to significant BEs in bare films. Quantitative comparison of simulations with experimental data is provided.

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Bauschinger and size effects in thin-film plasticity

Cited by 231 publications

References 37 publications

Generalizing J 2 flow theory: Fundamental issues in strain gradient plasticity

Generalizing J 2 flow theory: Fundamental issues in strain gradient plasticity

Indentation studies in b.c.c. crystals with enhanced model of strain-gradient crystal plasticity

Bauschinger effect in unpassivated freestanding thin films

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