A new algorithm for dense ellipse packing and polygonal structures generation in context of FEM or DEM

International audienceA new constructive ellipse packing algorithm is presented. It allows to respect the imposed area, shape and spatial orientation distribution (i.e. the inertia tensor) and achieve high packing densities. The packing density decreases with increasing particles aspect ratio what is in agreement with results reported in the literature. The generated packings with complex imposed area, shape and spatial orientation distributions with densities in the range of 0.74 and 0.8 are presented. The efficiency of the algorithm is demonstrated by comparison with the Optimized Dropping and Rolling method for disk packing. Moreover, the proposed packing strategy enables to generate very easily non-equiaxed polygonal structures by using Laguerre-Voronoï tessellation of the generated disk-based ellipse packing

A new algorithm for dense ellipse packing and polygonal structures generation in context of FEM or DEM

International audienceA new constructive ellipse packing algorithm is presented. It allows to respect the imposed area, shape and spatial orientation distribution (i.e. the inertia tensor) and achieve high packing densities. The packing density decreases with increasing particles aspect ratio what is in agreement with results reported in the literature. The generated packings with complex imposed area, shape and spatial orientation distributions with densities in the range of 0.74 and 0.8 are presented. The efficiency of the algorithm is demonstrated by comparison with the Optimized Dropping and Rolling method for disk packing. Moreover, the proposed packing strategy enables to generate very easily non-equiaxed polygonal structures by using Laguerre-Voronoï tessellation of the generated disk-based ellipse packing

Advancing layer algorithm of dense ellipse packing for generating statistically equivalent polygonal structures

International audienceA new constructive algorithm, called Advancing layer algorithm, for the generation of dense ellipse packing is proposed. Compared to existing algorithms for filling a 2D domain by elliptical particles, the method allows to respect the imposed size, shape and spatial orientation distributions (i.e. the inertia tensor) and achieve high packing densities. In particular case of disk packing, the comparison with Optimized Dropping and Rolling method shows that the computational cost of the proposed methodology is lower for moderate polydispersities of particle size while achieving higher packing densities and more homogeneous placing of particles in the domain. Thanks to an approximation of each ellipse by a set of circles, polygonal structures are constructed on the base of obtained ellipse packing by Laguerre–Voronoï Tessellation method in good agreement with desired characteristics of cells (polygons)

A new algorithm for dense ellipse packing and polygonal structures generation in context of FEM or DEM

A new constructive ellipse packing algorithm is presented. It allows to respect the imposed area, shape and spatial orientation distribution (i.e. the inertia tensor) and achieve high packing densities. The packing density decreases with increasing particles aspect ratio what is in agreement with results reported in the literature. The generated packings with complex imposed area, shape and spatial orientation distributions with densities in the range of 0.74 and 0.8 are presented. The efficiency of the algorithm is demonstrated by comparison with the Optimized Dropping and Rolling method for disk packing. Moreover, the proposed packing strategy enables to generate very easily non-equiaxed polygonal structures by using Laguerre-Voronoï tessellation of the generated disk-based ellipse packing

Effect of grain boundary trapping kinetics on diffusion in polycrystalline materials: hydrogen transport in Ni

Due to experimental limitations, the solute distribution in polycrystalline materials is difficult to obtain directly, especially in the vicinity of grain boundaries. Using a newly developed computational method which mixes continuum diffusion equations and atomic scale jump rates, we study the interstitial diffusion in solids containing interfaces taking into account trapping kinetics. The model is applied to hydrogen diffusion in Ni in elementary configurations: fast intergranular diffusion with no segregation (in agreement with Fisher's model), slow intergranular diffusion with trapping, diffusion through a triple junction and solute redistribution due to stress gradients across the interface. It is shown that the classical diffusion modes can be captured and a new diffusion regime with the effect of grain boundary trapping is revealed

Effect of intragranular strain heterogeneity on recrystallization kinetics assessed by numerical simulation at the mesoscopic scale

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Constraints on the CKM angle γ\gamma from B±→Dh±B^\pm\rightarrow Dh^\pm decays using D→h±h′∓π0D\rightarrow h^\pm h^{\prime\mp}\pi^0 final states

A data sample collected with the LHCb detector, corresponding to an integrated luminosity of $9~{\rm fb}^{-1}$, is used to measure $CP$ observables in $B^\pm \to D h^\pm$ decays, where $h^{(\prime)}$ is either a kaon or a pion, and the neutral $D$ meson decay is reconstructed in the three-body final states $K^\pm \pi^\mp \pi^0$, $\pi^\pm \pi^\mp \pi^0$, and $K^\pm K^\mp \pi^0$. The most suppressed of these modes, $B^\pm \to [\pi^\pm K^\mp \pi^0]_D K^\pm$, is observed with a significance greater than seven standard deviations and constraints on the CKM angle $\gamma$ are calculated from the combination of the measurements