A micromechanical model for the secondary creep of elasto-viscoplastic porous materials with two rate-sensitivity exponents: Application to a mixed oxide fuel

Wojtacki, Kajetan; Vincent, Pierre-Guy; Suquet, Pierre; Moulinec, Hervé; Boittin, Guylaine

doi:10.1016/j.ijsolstr.2018.12.026

Cited by 15 publications

(21 citation statements)

References 38 publications

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“…FFT-based computational techniques proved useful for studying the viscoelasticity of cement paste [310], mortar samples [311], cement [312] and concrete [313]. Furthermore, FFT-based techniques were used for studying explosive materials [314], secondary creep in a porous nuclear fuel [315], the thermal expansion of an energetic material [316], optical properties of deposit models for paint [317], dynamic recrystallization [318], to compute geodesics in two-dimensional media [182], fitting microstructure-property relationships [319], topology optimization [320] and for finding emerging microstructures associated to non-convex potentials [93,321].…”

Section: Miscellaneousmentioning

confidence: 99%

A review of nonlinear FFT-based computational homogenization methods

Schneider

2021

Acta Mech

150

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Since their inception, computational homogenization methods based on the fast Fourier transform (FFT) have grown in popularity, establishing themselves as a powerful tool applicable to complex, digitized microstructures. At the same time, the understanding of the underlying principles has grown, in terms of both discretization schemes and solution methods, leading to improvements of the original approach and extending the applications. This article provides a condensed overview of results scattered throughout the literature and guides the reader to the current state of the art in nonlinear computational homogenization methods using the fast Fourier transform.

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Section: Miscellaneousmentioning

confidence: 99%

A review of nonlinear FFT-based computational homogenization methods

Schneider

2021

Acta Mech

150

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“…where σ (k) denotes the volume average of the stress at iterate k and . denotes the Frobenius norms of a vector v or a second-order tensor τ [28]:…”

Section: Constitutive Crystal Plasticity Lawmentioning

confidence: 99%

Full-field polycrystal plasticity simulations of neutron-irradiated austenitic stainless steel: A comparison between FE and FFT-based approaches

Shawish

Vincent

Moulinec

et al. 2020

Journal of Nuclear Materials

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We compare two full-field approaches-a crystal plasticity finite element method (CP-FEM) and crystal plasticity fast Fourier transform-based (CP-FFT) method-for a specific crystal plasticity law introduced for neutron-irradiated austenitic stainless steel SA304L currently used in nuclear reactor vessel internals. This particular law is employed to identify and quantify possible advantages and drawbacks of the two approaches when used in the large-scale simulations to predict the effect of irradiation damage (e.g., crack initiation) in stainless steel microstructures. A comparison is performed in a polycrystalline context for different periodic Voronoi microstructures deformed under tension. Special emphasis is put on studying the performance of the two approaches in terms of mesh convergence analysis using aggregate models with different spatial discretizations. In the CP-FEM approach, the performance of linear as well as quadratic tetrahedral meshes is investigated. A similar performance between the CP-FEM and CP-FFT methods is demonstrated in a smaller 2-grain aggregate. However, a slower mesh convergence is observed for the CP-FEM method when comparing tensile responses of a larger 100-grain polycrystal. A drop in the convergence rate is much more pronounced on linear than on quadratic tetrahedral meshes. As a consequence, largest (average) grain boundary stresses are shown to be overestimated with the linear mesh CP-FEM approach, thus raising a concern of possible over-conservatism employed in the CP-FEM prediction of crack initiation in irradiated stainless steels. On the contrary, the mesh convergence of the CP-FFT approach is found to be practically independent of the applied macroscopic strain and also aggregate size. Therefore, for such steels, the CP-FFT approach seems to be better justified.

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“…The analytical description of the viscoplastic response contains an additional parameter q in the definition of the modified porosity f *. This parameter has been introduced following the experience of [27] with the so-called standard GTN model for isotropic porous plasticity to adjust the porosity percolation threshold at which the material is expected to completely loose its load carrying capacity [28]. A suitable value for q is identified by comparing the analytical and numerical predictions for the overall maximal stress under uniaxial tension.…”

Section: -2 Analytical Versus Numerical Modelsmentioning

confidence: 99%

Porous polycrystal plasticity modeling of neutron-irradiated austenitic stainless steels

Vincent

Moulinec

Joëssel

et al. 2020

Journal of Nuclear Materials

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A micromechanical model for quantifying the simultaneous influence of irradiation hardening and swelling on the mechanical stiffness and strength of neutron-irradiated austenitic stainless steels is proposed. The material is regarded as an aggregate of equiaxed crystalline grains containing a random dispersion of pores (large voids due to large irradiation levels) and exhibiting elastic isotropy but viscoplastic anisotropy. The overall properties are obtained via a judicious combination of various bounds and estimates for the elastic energy and viscoplastic dissipation of voided crystals and polycrystals. Reference results are generated with full-field numerical simulations for dense and voided polycrystals with periodic microstructures and crystal plasticity laws accounting for the evolution of dislocation and Frank loop densities. These results are calibrated with experimental data available from the literature and are employed to assess the capabilities of the proposed model to describe the evolution of mechanical properties of highly irradiated Solution Annealed 304L steels at 330oC. The agreement between model predictions and simulations is seen to be quite satisfactory over the entire range of porosities and loadings investigated. The expected decrease of overall elastic properties and strength for porosities observed at large irradiation levels is reported. The mathematical simplicity of the proposed model makes it particularly apt for implementation into finiteelement codes for structural safety analyses.

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A micromechanical model for the secondary creep of elasto-viscoplastic porous materials with two rate-sensitivity exponents: Application to a mixed oxide fuel

Cited by 15 publications

References 38 publications

A review of nonlinear FFT-based computational homogenization methods

A review of nonlinear FFT-based computational homogenization methods

Full-field polycrystal plasticity simulations of neutron-irradiated austenitic stainless steel: A comparison between FE and FFT-based approaches

Porous polycrystal plasticity modeling of neutron-irradiated austenitic stainless steels

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