Overall viscoplastic behavior of non-irradiated porous nuclear ceramics

Yann Monerie (1) , Jean-Marie Gatt (1)

1 CEA - Commissariat à l'énergie atomique et aux énergies alternatives

This paper deals with the overall behavior of nonlinear viscous and porous nuclear ceramics. Bi-viscous isotropic porous materials are considered: the matrix is subjected to two power-law viscosities with different exponents related to two stationary temperature-activated creeping mechanisms (scattering-creep and dislocation-creep), and this matrix contains a low porosity volume fraction. The overall behavior of these types of composite materials is obtained with the help of quadratic strain-rate potentials combined with experimental-based coupling function depending on stress and temperature. For each creeping mechanism, the hollow sphere model of [Michel, J.-C., Suquet, P., 1992. The constitutive law of nonlinear viscous and porous materials. Journal of the Mechanics and Physics of Solids 40, 783–812] is used. Mechanical parameters of the resulting model are identified and validated in the particular case of non-irradiated uranium dioxide nuclear ceramics. This model predicts, under pure thermo-mechanical loading, a variation of the material volume and a variation of the porosity volume fraction (the so-called densification or swelling).

Mots clés: Overall behavior; Porous materials; Nonlinear viscosity; Nuclear ceramics

Domaines: Sciences de l'ingénieur [physics]

Yann Monerie, Jean-Marie Gatt. Overall viscoplastic behavior of non-irradiated porous nuclear ceramics. Mechanics of Materials, 2006, 38 (7), pp.608-619. ⟨10.1016/j.mechmat.2005.11.004⟩. ⟨hal-03143894⟩