Dilatational viscoplasticity of polycrystalline solids with intergranular cavities
Résumé
We propose constitutive models for polycrystalline aggregates with intergranular cavities and test them against full-field numerical simulations. Such conditions are prevalent in many engineering applications and failure of metallic components (e.g. HIPing and other forming processes, spallation under dynamic loading conditions, etc.), where the dilatational effects associated with the presence of cavities must be accounted for, and standard polycrystalline models for incompressible plasticity are not appropriate. On the other hand, it is not clear that the use of porous plasticity models with isotropic matrix behavior is relevant, particularly, when large deformations can lead to significant texture evolution and therefore to strong matrix anisotropy. Of course, finite strains can also lead to significant changes in the porosity and pore shape, resulting in additional anisotropy development. In this work, we make use of 'variational linear-comparison' homogenization methods to develop constitutive models simultaneously accounting for texture of the matrix, porosity and average pore shape and orientation. The predictions of the models are compared with full-field numerical simulations based on fast Fourier transforms to study the influence of different microstructural features (e.g. overall porosity, texture of the matrix phase, single-crystal anisotropy, etc.) and type of loading (triaxiality) on the dilatational viscoplastic behavior of voided polycrystals. The results are also compared with the predictions of isotropic-matrix porous plasticity models to assess the effect of the possible matrix anisotropy in textured samples. © 2011 Taylor & Francis.
Mots clés
Anisotropic property
Dilatational effects
Dynamic loading conditions
Engineering applications
Finite strain
Forming process
Full-field
Intergranular cavity
Isotropic matrix
Large deformations
matrix
Matrix phase
Metallic component
Microstructural features
Polycrystalline aggregates
Polycrystalline models
Polycrystalline solid
Pore shape
Porous plasticity
Texture evolutions
Triaxiality
Viscoplastic
voids
Anisotropy
Constitutive models
Curricula
Dynamic loads
Fast Fourier transforms
Forecasting
Homogenization method
Microstructural evolution
Models
Polycrystals
Porosity
Textures
Computer simulation