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3D VS. 2D MODELLING OF CRACKING AND PLASTICITY IN POLYCRYSTALLINE MATERIALS

Paggi, M.; Lehmann, E.; Weber, C.; Carpinteri, A.; Wriggers, P.;

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The problem of cracking and plasticity in face-centered-cubic polycrystals is herein investigated. The aim is to quantify the difference between 3D simulations, computationally expensive but able to model real polycrystalline geometries, and simplified computations on 2D cross-sections with a reduced computational cost. To this aim, a unified finite element formulation with elasto-plastic elements for the grain interior and interface elements for the grain boundaries is developed. This approach is suitable for the analysis of polycrystalline materials with a response intermediate between that of brittle ceramics and that of ductile metals. Crystal plasticity theory is used for 3D computations, whereas isotropic VON MISES plasticity is adopted for the 2D tests. For the grain boundaries, a cohesive zone model (CZM) accounting for Mode Mixity is considered. Examining the nonlinearity due to the CZM only, 3D simulations of uniaxial tensile tests differ from 2D predictions due to the higher tortuosity of the crack path in 3D, leading to significant Mixed Mode deformation. Regarding the comparison between 3D and 2D simulations with plasticity only, results show that the saturation of the stress field is much faster in 3D than in 2D. Finally, when both nonlinearities are simultaneously present, a strong interplay is evidenced. The CZM prevails over plasticity for low deformation levels. Afterwards, plasticity prevails over CZM. Finally, for a very large deformation, failure is ruled by the CZM formulation which induces a softening in the global structural response and a size-scale dependency of the results.

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Palavras-chave: Cohesive Zone Model, Crystal plasticity, Isotropic plasticity, Finite element method, Polycrystalline materials.,

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DOI: 10.5151/meceng-wccm2012-18522

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Como citar:

Paggi, M.; Lehmann, E.; Weber, C.; Carpinteri, A.; Wriggers, P.; "3D VS. 2D MODELLING OF CRACKING AND PLASTICITY IN POLYCRYSTALLINE MATERIALS", p. 1702-1721 . In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1]. São Paulo: Blucher, 2014.
ISSN 2358-0828, DOI 10.5151/meceng-wccm2012-18522

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