Physically-Based Simulations of the Cyclic Behavior of FCC Polycrystals

Sauzay, Maxime; Liu, Jia; Rachdi, Fatima; Signor, Loïc; Ghidossi, Thomas; Villechaise, Patrick

doi:10.4028/www.scientific.net/amr.891-892.833

Cited by 12 publications

(7 citation statements)

References 17 publications

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“…FFT results indicate that the field histograms for the strain and stress components are almost identical for the Voronoï, standard and anisotropic Johnson-Mehl models (not shown). This lack of sensitivity with respect to the microstructure has been noticed in other works in linear elasticity [32]. In the present material, this is explained by the moderate contrast between elastic moduli.…”

Section: Local Fieldssupporting

confidence: 78%

A Fourier-based numerical homogenization tool for an explosive material

Gasnier

Willot

Trumel

et al. 2015

Matériaux & Techniques

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This paper describes the development of a numerical homogenization tool adapted to TATB-based pressed explosives. This is done by combining virtual microstructure modeling and Fourier-based computations. The polycrystalline microstructure is represented by a Johnson-Mehl tessellation model with Poisson random nucleation and anisotropic growth of grains. Several calculations are performed with several sets of available data for the thermoelastic behavior of TATB. Good agreement is found between numerical predictions and experimental data regarding the overall thermal expansion coefficient. The results are shown to comply with available bounds on polycrystalline anisotropic thermoelasticity. Finally, the size of the representative volume element is derived for the bulk, shear and volumetric thermal expansion moduli.

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Section: Local Fieldssupporting

confidence: 78%

A Fourier-based numerical homogenization tool for an explosive material

Gasnier

Willot

Trumel

et al. 2015

Matériaux & Techniques

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“…The effect of the choice of the tessellation model for the TATB material on the fields distribution, outside of the present study, will be investigated in a future work. In any case, accurate modeling of the polycrystal geometry is presumably important to incorporate the effect of the binder, to predict strain field localization or fracture (Sauzay et al, 2014).…”

Section: Field Distributionsmentioning

confidence: 99%

“…The results above do not necessarily depend on the geometric model chosen for the polycrystal. In a previous work based on finite element computations (Sauzay et al, 2014), the elastic and plastic strain and stress fields occurring in the 3D PoissonVoronoï model and in a simplified model with cubic-shaped grains have been computed. Slightly broader field distributions have been predicted for polyhedric grains rather than cubic grains, but overall the strain and stress histograms for the two geometries are very close to one another.…”

Section: Field Distributionsmentioning

confidence: 99%

Numerical modeling of the thermal expansion of an energetic material

Ambos

Willot

Jeulin

et al. 2015

International Journal of Solids and Structures

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Two typos in the last two equations in the appendix have been corrected (changes highlighted in red). This preprint is consistent with the published version. Results unchanged.International audienceThe thermoelastic response of a TATB-based pressed explosive is studied using morphological modeling and a numerical Fourier scheme. First, we characterize the polycrystalline-like microstructure in terms of the (2D) granulometry and covariance functions, measured on SEM micrograph images. The granulometry is found to be close to a Rayleigh distribution. Second, we represent the polycrystal by a modified Johnson-Mehl tessellation with time-varying germination-rate, in order to approach the wide size distribution observed on the SEM images. We find excellent agreement between the numerically optimized model and the real material in terms of granulometry. Third, we compute the thermoelastic response of the microstructure model by means of full-field Fourier-based computations. Each crystal is assigned uncorrelated random orientations. The thermomechanical response of single crystals is provided by the molecular dynamic simulations of Bedrov et al. (2009) and the X-ray diffraction results of Kolb et al. (1979). Macroscopic (uniform) temperature or strain loadings are applied along various directions (tension, shear or hydrostatic). We observe strong internal stresses upon heating, owing to the highly anisotropic thermoelastic response of TATB and random crystallographic orientations in the polycrystal. The largest stress and strain gradients are observed at grain boundaries, enforcing the idea that grain boundary fracture is indeed the irreversible mechanism underlying ratchet growth. As a first attempt to account for the plastic binder, a 4-voxels soft interphase is inserted at grain boundaries. This results in a strong softening effect on elastic macroscopic properties

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“…These approaches are computationally and experimentally too demanding to support parametric simulations to assess the intrinsic statistical variability of microstructures. In addition, Sauzay and collaborators [28] have shown that meshes with highly detailed microstructures and simple meshes with cubic grains result in only minor differences regarding the distributions of the mean plastic strain per grain. Therefore, the use of nonlocal averaging schemes for FIPs combined with coarse meshes is quite promising to support practical parametric simulations to assess statistics of microstructure influence on fatigue resistance.…”

Section: Introductionmentioning

confidence: 97%

Microstructure and mesh sensitivities of mesoscale surrogate driving force measures for transgranular fatigue cracks in polycrystals

Castelluccio

McDowell

2015

Materials Science and Engineering: A

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a b s t r a c tThe number of cycles required to form and grow microstructurally small fatigue cracks in metals exhibits substantial variability, particularly for low applied strain amplitudes. This variability is commonly attributed to the heterogeneity of cyclic plastic deformation within the microstructure, and presents a challenge to minimum life design of fatigue resistant components. This paper analyzes sources of variability that contribute to the driving force of transgranular fatigue cracks within nucleant grains. We employ crystal plasticity finite element simulations that explicitly render the polycrystalline microstructure and Fatigue Indicator Parameters (FIPs) averaged over different volume sizes and shapes relative to the anticipated fatigue damage process zone. Volume averaging is necessary to both achieve description of a finite fatigue damage process zone and to regularize mesh dependence in simulations. Results from constant amplitude remote applied straining are characterized in terms of the extreme value distributions of volume averaged FIPs. Grain averaged FIP values effectively mitigate mesh sensitivity, but they smear out variability within grains. Volume averaging over bands that encompass critical transgranular slip planes appear to present the most attractive approach to mitigate mesh sensitivity while preserving variability within grains.Published by Elsevier B.V.

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Physically-Based Simulations of the Cyclic Behavior of FCC Polycrystals

Abstract: Two homogeneization approaches are used in order predict the cyclic elastic-plastic behaviour of 316L(N) polycrystals, either

Cited by 12 publications

References 17 publications

A Fourier-based numerical homogenization tool for an explosive material

A Fourier-based numerical homogenization tool for an explosive material

Numerical modeling of the thermal expansion of an energetic material

Microstructure and mesh sensitivities of mesoscale surrogate driving force measures for transgranular fatigue cracks in polycrystals

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