A dislocation density based constitutive model for crystal plasticity FEM including geometrically necessary dislocations

Ma, Anxin; Roters, Franz; Raabe, Dierk

doi:10.1016/j.actamat.2006.01.005

Cited by 355 publications

(215 citation statements)

References 22 publications

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“…The shortcoming of such viscoplastic formulations is the absence of an internal variable concept beyond the incorporation of the crystal orientation. More advanced variants of the crystal plasticity finite element method, therefore, replace the viscoplastic constitutive description by dislocation-based models [9,10,[19][20][21][22][23][24][25][26]. Since it is likely that some dislocation effects which cannot be readily captured by viscoplastic hardening laws may play a substantial role in nanoindentation of single crystals, we use in this study an advanced crystal plasticity finite element method which is based on dislocation rate formulations for the simulation of nanoindentation.…”

Section: Motivationmentioning

confidence: 99%

“…For this purpose, we take the following approach: first, the rotation patterns are investigated by a high-resolution three-dimensional (3D) EBSD technique (EBSD tomography) for a nanoindent performed by a conical indenter with a spherical tip in a copper single crystal. Next, we conduct advanced crystal plasticity finite element simulations which are based not on a viscoplastic formulation but on a dislocation density-based constitutive model [9,10]. Finally, the results are discussed in terms of a geometrical model which simplifies the boundary conditions imposed during indentation in terms of a compressive state normal to the local tangent of the indent rim.…”

Section: Introductionmentioning

confidence: 99%

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On the origin of deformation-induced rotation patterns below nanoindents

et al. 2008

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Section: Motivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the origin of deformation-induced rotation patterns below nanoindents

et al. 2008

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“…These GNDs, which are equivalent to a local accumulation of dislocations with the same sign, can be included as hardening terms in strain gradient plasticity, such as those proposed by Ashby [23], Fleck et al [24] and Gao et al [25]. Plastic strain gradients can play a critical role in understanding size effects present in most material systems and mechanical tests, either due to sample geometry or strain gradients developed because of heterogeneous microstructures, resulting in extra hardening effects [26] and can be incorporated into crystal plasticity finite element models [27][28][29].…”

Section: Introductionmentioning

confidence: 99%

On the mechanistic basis of fatigue crack nucleation in Ni superalloy containing inclusions using high resolution electron backscatter diffraction

et al. 2015

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This is an authors' copy of a manuscript published in Acta Materialia Volume 97, 15 September 2015, Pages 367-379. http://dx.doi.org/10.1016/j.actamat.2015.06.035 AbstractA series of interrupted three-point bend low-cycle fatigue tests were carried out on a powder metallurgy FHG96 nickel superalloy sample containing non-metallic inclusions. High resolution electron backscatter diffraction (HR-EBSD) was used to characterize the distribution and evolution of geometrically necessary dislocation (GND) density, residual stress and total dislocation density near a non-metallic inclusion. A systematic study of room temperature cyclic deformation is presented in which slip localisation, cyclic hardening, ratcheting and stabilisation occur, through to crack formation and microstructurally-sensitive propagation. Particular focus is brought to bear at the inclusion-matrix interface. Complex inhomogeneous deformation structures were directly observed from the first few loading cycles, and these structures were found not to vary significantly with increasing number of cycles. A clear link was observed between crack nucleation site and microstructurally-sensitive growth path and the spatially-resolved sites of extreme values of residual stress and GND density.

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“…There are two main groups of constitutive models differentiated by the nature of the state variable they use: phenomenological models mostly use a critical resolved shear stress as state variable for each slip system [19][20][21][22], while physically-based constitutive models rely on the dislocation density as state variable since dislocations are considered the main carriers of plasticity [23][24][25]. Most of the existing CP frameworks have been focused on fcc metals [26][27][28][29], while only a few studies have been devoted to study bcc plasticity.…”

Section: Introductionmentioning

confidence: 99%

Linking atomistic, kinetic Monte Carlo and crystal plasticity simulations of single‐crystal tungsten strength

et al. 2015

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Understanding and improving the mechanical properties of tungsten is a critical task for the materials fusion energy program. The plastic behavior in body‐centered cubic (bcc) metals like tungsten is governed primarily by screw dislocations on the atomic scale and by ensembles and interactions of dislocations at larger scales. Modeling this behavior requires the application of methods capable of resolving each relevant scale. At the small scale, atomistic methods are used to study single dislocation properties, while at the coarse‐scale, continuum models are used to cover the interactions between dislocations. In this work we present a multiscale model that comprises atomistic, kinetic Monte Carlo (kMC) and continuum‐level crystal plasticity (CP) calculations. The function relating dislocation velocity to applied stress and temperature is obtained from the kMC model and it is used as the main source of constitutive information into a dislocation‐based CP framework. The complete model is used to perform material point simulations of single‐crystal tungsten strength. We explore the entire crystallographic orientation space of the standard triangle. Non‐Schmid effects are inlcuded in the model by considering the twinning‐antitwinning (T/AT) asymmetry in the kMC calculations. We consider the importance of 〈111〉{110} and 〈111〉{112} slip systems in the homologous temperature range from 0.08Tm to 0.33Tm, where Tm =3680 K is the melting point in tungsten. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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A dislocation density based constitutive model for crystal plasticity FEM including geometrically necessary dislocations

Cited by 355 publications

References 22 publications

On the origin of deformation-induced rotation patterns below nanoindents

On the origin of deformation-induced rotation patterns below nanoindents

On the mechanistic basis of fatigue crack nucleation in Ni superalloy containing inclusions using high resolution electron backscatter diffraction

Linking atomistic, kinetic Monte Carlo and crystal plasticity simulations of single‐crystal tungsten strength

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