Overall viscoplastic behavior of non-irradiated porous nuclear ceramics

Monerie, Yann; Gatt, Jean-Marie

doi:10.1016/j.mechmat.2005.11.004

Cited by 18 publications

(20 citation statements)

References 26 publications

(40 reference statements)

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“…The only active mechanism is dislocation motion for which the rate-sensitivity exponent n is found in the literature to range between 4.5 and 17 (Guerin, 1975). A commonly accepted value is n ¼ 8 ( Monerie and Gatt, 2006) which, compared to n ¼ 1 for diffusion, allows us to consider that viscosity effects are small. This observation has been summarized in Sauter and Leclercq (2003) by saying that ''the behavior of uranium dioxide tends to be more plastic than viscous".…”

Section: Matrix Constitutive Relationsmentioning

confidence: 99%

Porous materials with two populations of voids under internal pressure: I. Instantaneous constitutive relations

Vincent

Monerie

Suquet

2009

International Journal of Solids and Structures

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International audienceThis study is devoted to the mechanical behavior of uranium dioxide (UO2) which is a porous material with two populations of voids of very different size subjected to internal pressure. The smallest voids are intragranular and spherical in shape whereas the largest pores located at the grain boundary are ellipsoidal and randomly oriented. In this first part of the study, attention is focused on the effective properties of these materials with fixed microstructure. In a first step the poroelastic properties of these doubly voided materials are studied. Then two rigorous upper bounds are derived for the effective poro-plastic constitutive relations of these materials. The first bound, obtained by generalizing the approach of Gologanu et al. (1994) to compressible materials, is accurate at high stress-triaxiality. The second one, which derives from the variational method of Ponte Casta˜neda (1991), is accurate when the stress triaxiality is low. A N-phase model, inspired by Bilger et al. (2002), is proposed which matches the best of the two bounds at low and high triaxiality. The effect of internal pressures is discussed. In particular it is shown that when the two internal pressures coincide, the effective flow surface of the saturated biporous material is obtained from that of the drained material by a shift along the hydrostatic axis. However, when the two pressures are different, the modifications brought to the effective flow surface in the drained case involve not only a shift along the hydrostatic axis but also a change in shape and size of the surface

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Section: Matrix Constitutive Relationsmentioning

confidence: 99%

Porous materials with two populations of voids under internal pressure: I. Instantaneous constitutive relations

Vincent

Monerie

Suquet

2009

International Journal of Solids and Structures

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“…Following Monerie and Gatt [52], the equivalent stress s eq  p, σ eq , f  is defined as function of the hydrostatic pressure p = 1 3 tr (σ ), the Von-Mises stress σ eq and the porosity f :…”

Section: Compressible Viscoplastic Behaviourmentioning

confidence: 99%

Introducing the open-source mfront code generator: Application to mechanical behaviours and material knowledge management within the PLEIADES fuel element modelling platform

Helfer

Michel

Proix³

et al. 2015

Computers & Mathematics with Applications

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Available online xxxx Keywords:Material knowledge management Mechanical behaviour integration Implicit integration schemes Single crystal plasticity Domain specific languages a b s t r a c tThe PLEIADES software environment is devoted to the thermomechanical simulation of nuclear fuel elements behaviour under irradiation. This platform is co-developed in the framework of a research cooperative program between Électricité de France (EDF), AREVA and the French Atomic Energy Commission (CEA). As many thermomechanical solvers are used within the platform, one of the PLEAIADES's main challenge is to propose a unified software environment for capitalisation of material knowledge coming from research and development programs on various nuclear systems. This paper introduces a tool called mfront which is basically a code generator based on C++ (Stroustrup and Eberhardt, 2004). Domain specific languages are provided which were designed to simplify the implementations of new material properties, mechanical behaviours and simple material models. mfront was recently released under the GPL open-source licence and is available on its web site: http://tfel.sourceforge.net/.The authors hope that it will prove useful for researchers and engineers, in particular in the field of solid mechanics. mfront interfaces generate code specific to each solver and language considered.In this paper, after a general overview of mfront functionalities, a particular focus is made on mechanical behaviours which are by essence more complex and may have significant impact on the numerical performances of mechanical simulations. mfront users can describe all kinds of mechanical phenomena, such as viscoplasticity, plasticity and damage, for various types of mechanical behaviour (small strain or finite strain behaviour, cohesive zone models). Performance benchmarks, performed using the Code_Aster finite element solver, show that the code generated using mfront is in most cases on par or better than the behaviour implementations written in fortran natively available in this solver. The material knowledge management strategy that was set up within the PLEIADES platform is briefly discussed. A material database named sirius proposes a rigorous material verification workflow.We illustrate the use of mfront through two case of studies: a simple FFC single crystal viscoplastic behaviour and the implementation of a recent behaviour for the fuel material which describes various phenomena: fuel cracking, plasticity and viscoplasticity.

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“…Creep deformations of ceramic materials are important in many high temperature, engineering applications, ranging from high performance gas turbines [2], hot isostatic pressing [22], porous ceramic nuclear fuels [17], and refractory materials in the steel industry. Although viscous phenomena in ceramics are mostly evident at high temperature, delayed phenomena might assume a non-negligible role also in some applications at room temperature, for instance involving the mechanical response of the ceramic powders.…”

Section: Introductionmentioning

confidence: 99%

“…The first approach takes account of the cited ductility at high temperature and is based on the use of Gurson's model [8] for defining the flow potential of a hardening porous solid, and Duva & Hutchinson's model [10] for defining the strain rate potential of a voided material. This approach has been followed for instance by [5,16,17].…”

Section: Introductionmentioning

confidence: 99%

“…The experimental results were obtained at room temperature and showed that two deformation mechanisms can be recognized for both elastic and plastic strains, namely a short-term (immediate) mechanism, and a long-term, viscous one. Even in ceramics at high temperature, [17], proposed the existence of two creep mechanisms: the scattering-creep and the dislocation-creep. Thus the existence of two (or more) deformation mechanisms in ceramics and geomaterials is physically well motivated and can be reasonably expected.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A two-yield surfaces, viscoplastic constitutive model for ceramics and geomaterials

Madaschi

Gajo

2016

Journal of the European Ceramic Society

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Overall viscoplastic behavior of non-irradiated porous nuclear ceramics

Cited by 18 publications

References 26 publications

Porous materials with two populations of voids under internal pressure: I. Instantaneous constitutive relations

Porous materials with two populations of voids under internal pressure: I. Instantaneous constitutive relations

Introducing the open-source mfront code generator: Application to mechanical behaviours and material knowledge management within the PLEIADES fuel element modelling platform

A two-yield surfaces, viscoplastic constitutive model for ceramics and geomaterials

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