A micromechanical approach based on Fourier transforms and continuum dislocation mechanics to simulate grain size effects in polycrystals

Coupling of Elasto-Visco-Plastic (EVP) Fast Fourier Transform (FFT)-based formulation initially developed for conventional crystal plasticity and the phenomenological Mesoscale Field Dislocation Mechanics (MFDM) theory.

The combined “MFDM-EVPFFT” model accounts for plastic flow and hardening from densities of geometrically necessary dislocations (or “GND”) in addition to statistically stored dislocations (“SSD”).

The model captures GND density evolution through a filtered numerical spectral approach, which is coupled with stress equilibrium through the EVPFFT algorithm. The discrete Fourier transform method together with finite difference schemes is applied to solve both lattice incompatibility problem and Lippmann-Schwinger equation. Numerical results are first presented for two-phase laminate composites with plastic single crystal channels and elastic precipitates. First, a channel size effect on the overall behavior of laminate composites is obtained due to the pile up of GND densities at interfaces between hard and soft phases. Second, 3D face-centered cubic (FCC) polycrystals using periodic Voronoï tessellations are considered. In comparison with the conventional Crystal Plasticity model (CP-EVPFFT), it is shown that grain size effects occur on the flow stress of polycrystals during monotonic loadings. In addition, GND effects on backstress and plastic strain profiles during reversible loadings are investigated with the present MFDM-EVPFFT numerical approach.

Prof. Stéphane Berbenni Prof. Vincent Taupin

Directeur de recherche CNRS - Department 2 IMPACT

University of Lorraine UdL LEM3 

(Ingénierie des Microstructures, Procédés, Anisotropie, ComportemenT)

(Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux)


Laboratoire LEM3, UMR CNRS 7239
7 rue Félix Savart
F-57070 METZ

France

Phone

+33 3-72-74-78-42

+33 3-72-74-78-43
Email

Http Prof. S. Berbenni Prof. V. Taupin
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