Modelling the torsion of thin metal wires by distortion gradient plasticity

Bardella, Lorenzo; Panteghini, Andrea

doi:10.1016/j.jmps.2015.03.003

Cited by 99 publications

(73 citation statements)

References 64 publications

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“…Recently, Bardella (2010), Bardella and Panteghini (2015), and Fleck et al (2015) also proposed expressions for the free energy similar to Eq. (18).…”

Section: Back Stress Formulations and Resultsmentioning

confidence: 99%

On modeling micro-structural evolution using a higher order strain gradient continuum theory

El-Naaman

Nielsen

Niordson

2016

International Journal of Plasticity

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Published experimental measurements on deformed metal crystals show distinct pattern formation, in which dislocations are arranged in wall and cell structures. The distribution of dislocations is highly non-uniform, which produces discontinuities in the lattice rotations. Modeling the experimentally observed micro-structural behavior, within a framework based on continuous field quantities, poses obvious challenges, since the evolution of dislocation structures is inherently a discrete and discontinuous process. This challenge, in particular, motivates the present study, and the aim is to improve the micro-structural response predicted using strain gradient crystal plasticity within a continuum mechanics framework. One approach to modeling the dislocation structures observed is through a back stress formulation, which can be related directly to the strain gradient energy. The present work offers an investigation of constitutive equations for the back stress based on both considerations of the gradient energy, but also includes results obtained from a purely phenomenological starting point. The influence of model parameters is brought out in a parametric study, and it is demonstrated how a proper treatment of the back stress enables dislocation wall and cell structure * Tel: +45 4525-4020, Fax: +45 4593-1475 URL: saeln@mek.dtu.dk (S.A. El-Naaman)

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“…Recently, Bardella (2010), Bardella and Panteghini (2015), and Fleck et al (2015) also proposed expressions for the free energy similar to Eq. (18).…”

Section: Back Stress Formulations and Resultsmentioning

confidence: 99%

On modeling micro-structural evolution using a higher order strain gradient continuum theory

El-Naaman

Nielsen

Niordson

2016

International Journal of Plasticity

View full text Add to dashboard Cite

show abstract

“…Very recently Fleck, Hutchinson and Willis [18,22,23] noted that non-incremental dissipative higher order terms may lead to a delay in plastic flow under certain non-proportional loading conditions. This has been numerically corroborated by Bardella and Panteghini [56] and by Martínez-Pañeda et al [57]. This physically uncertain response may favor the incremental modeling approach suggested by Hutchinson [22] where increments of all stress magnitudes are expressed in terms of increments of strain.…”

Section: Thermodynamically Consistent Constitutive Equationsmentioning

confidence: 66%

“…This is the case of the very recent FE implementation of Poh and Peerlings [59] and the earlier work by Ostien and Garikipati [79], who implemented Gurtin (2004) [15] theory within a Discontinuous Galerkin framework. Energetic and dissipative contributions are both accounted for in the recent ad hoc FE formulation for the torsion problem by Bardella and Panteghini [56], also showing that, contrary to higher-order SGP theories, Gurtin (2004) DGP can predict some energetic strengthening even with a quadratic defect energy.…”

Section: A Finite Element Basis For Dgpmentioning

confidence: 96%

“…It has been consistently shown (see, e.g., [56,58,59]) that the use of phenomenological higher order models that involve the whole plastic distortion (here referred to as Distortion Gradient Plasticity, DGP) leads to superior modeling capabilities. Hence, a distinct feature of Gurtin 2004 DGP [15] is the constitutive inclusion of the plastic rotation through the prescription of a free energy dependent on Nye's dislocation density tensor [60].…”

Section: Distortion Gradient Plasticitymentioning

confidence: 99%

“…but one should note that exploring other options may lead to further modeling capabilities (see [56,58]), with recoverable gradient effects contributing to both hardening and strengthening. Accordingly, the defect stress equals:…”

Section: Energetic Contributionsmentioning

confidence: 99%

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