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Sornin D.,Gif sur Yvette | Pachon-Rodriguez E.A.,Gif sur Yvette | Pachon-Rodriguez E.A.,ArcelorMittal | Vanegas-Marquez E.,Gif sur Yvette | And 2 more authors.
Journal of Materials Engineering and Performance | Year: 2016

For new fast-neutron sodium-cooled Generation IV nuclear reactors, the candidate cladding materials for the very strong burn-up are ferritic and martensitic oxide dispersion strengthened grades. Classically, the cladding tube is cold formed by a sequence of cold pilger milling passes with intermediate heat treatments. This process acts upon the geometry and the microstructure of the tubes. Consequently, crystallographic texture, grain sizes and morphologies, and tube integrity are highly dependent on the pilgering parameters. In order to optimize the resulting mechanical properties of cold-rolled cladding tubes, it is essential to have a thorough understanding of the pilgering process. Finite Element Method (FEM) models are used for the numerical predictions of this task; however, the accuracy of the numerical predictions depends not only on the type of constitutive laws but also on the quality of the material parameters identification. Therefore, a Chaboche-type law which parameters have been identified on experimental observation of the mechanical behavior of the material is used here. As a complete three-dimensional FEM mechanical analysis of the high-precision tube rolling (HPTR) cold pilgering of tubes could be very expensive, only the evolution of geometry and deformation is addressed in this work. The computed geometry is compared to the experimental one. It is shown that the evolution of the geometry and deformation is not homogeneous over the circumference. Moreover, it is exposed that the strain is nonhomogeneous in the radial, tangential, and axial directions. Finally, it is seen that the dominant deformation mode of a material point evolves during HPTR cold pilgering forming. © 2016 ASM International

Doligez B.,French Institute of Petroleum | Hamon Y.,French Institute of Petroleum | Barbier M.,French Institute of Petroleum | Nader F.,French Institute of Petroleum | And 2 more authors.
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2011

The relationships between sedimentological facies and diagenetic properties differ depending on burial and geological history. In this paper we propose several examples where different quantitative expressions of diagenetic imprints lead to different workflows to be applied, to obtain final simulations reproducing both the sedimentary facies and the diagenetic trends in reservoir models. A first case is based on an outcrop study of mixed siliciclastic- carbonate facies. The relationships between sedimentary facies and diagenesis have been used to define truncation rules for the plurigaussian algorithm, which aims at simulating both the distribution of sedimentary facies and the diagenetic overprint. Another workflow has been developed on this example, using the bi-plurigaussian simulation algorithm to address the problem of heterotopic bivariate conditional simulation (the two variables are known at different locations). A second example is related to early diagenesis characterization. In this example (Madison Formation, Wyoming, USA), diagenetic imprints have been quantified, corresponding to a succession of diagenetic phases (micritization, calcite cementation, dolomitization...), that can coexist in the same sedimentary facies. The workflow using plurigaussian and nested simulation algorithms shows the impact of such joint simulations, as the diagenesis may completely modify the distribution of reservoir properties only based on a facies simulation. In a third example, the modeled Aptian/Albian formation includes hydrothermal dolomites (HDT) associated to fractures and faults hosted in reefal and slope limestones. Simulations succeed in redistributing the HTD correctly at the surface and in the subsurface. Hence, in the deeper parts of the Aptian/Albian reefal rock unit, the dolomite is inherently associated to fractures, while at shallower levels, dolomitization seems to be more lateral, affecting probably more permeable facies. These results provide insights and numerical means for estimating volumes of dolomites (vertically and laterally) in an excellent case study of fracture-related HTD. Diagenesis alters the original relationships between depositional facies and petrophysical properties in a reservoir. The quantitative integration of sedimentological facies and diagenetic properties is a key point to obtain a realistic geological model in reservoir studies. Copyright 2011, Society of Petroleum Engineers.

Bunsell A.R.,Air Liquide | Barbier F.,MinesParisTech | Thionnet A.,Air Liquide | Zejli H.,Air Liquide | Besancon B.,MinesParisTech
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

Efficient storage of hydrogen is critical to the success of transition markets for hydrogen energy. For these near-term niche markets, high pressure compressed gas storage in carbon fiber composite pressure vessels is currently the most advanced and promising technology. However, challenges remain to improve performance and reliability while still insuring the safety of these pressure vessels in service over periods of 15 to 20 years. In order to avoid overdesign and conservative use, a fundamental understanding of damage mechanisms and degradation of these materials is required to fully exploit the potential of these materials. Acoustic emission has thus been used to characterize damage accumulation and its kinetics under static and cyclic loading in carbon fiber composite samples and pressure vessels. These experimental results were complemented by finite element modeling taking into account the elastic nature of the fibers, coupled with the visco-elastic behavior of the matrix and debonding at the fiber matrix interface.Copyright © 2010 by ASME.

Kaabi A.,MinesParisTech | Bienvenu Y.,MinesParisTech | Pierre B.,GRISET S.A. | Prevond L.,CNAM SATIE
MATEC Web of Conferences | Year: 2013

The powerchain in electric vehicles sets new demands on semi conductors and their packaging. The latter will be specifically addressed. The power density per cm2 in DC/DC or DC/AC converters requires a mastering of thermomecahnical aspects. The temperature cyling, the environment under the hood of the vehicles and the "hybrid" technology impose severe constraints on the assemblies which may be met by architectured substrates, new options for assemblies and efficient cooling systems. An optimised semi conductor substrate associating copper and invar in a will be developed, relying on roll bonding to produce the 3D architecture. Roll bonding may also be used to associate aluminium and iron to produce light laminates with a CEM performance. © Owned by the authors, published by EDP Sciences, 2013.

Hellouin De Menibus A.,CEA Saclay Nuclear Research Center | Auzoux Q.,CEA Saclay Nuclear Research Center | Besson J.,MinesParistech | Crepin J.,MinesParistech
Journal of Nuclear Materials | Year: 2014

This study is focused on the impact of rapid Reactivity Initiated Accident (RIA) representative strain rates (about 1 s-1 NEA, 2010) on the behavior and fracture of unirradiated cold work stress relieved Zircaloy-4 cladding tubes. Uniaxial ring tests (HT) and plane strain ring tensile tests (PST) were performed in the 0.1-10 s-1 strain rate range, at 25 °C. The local temperature increase due to plastic dissipation was measured with a high-speed infrared camera. Limited temperature increases were measured at 0.1 s-1 strain rate. Limited but not strongly localized temperature increases were measured at 1 s-1. Large temperature increase were measured at 5 and 10 s-1 (142 °C at 5 s -1 strain rate in HT tests). The local temperature increase induced heterogeneous temperature fields, which enhanced strain localization and resulted in a reduction of the plastic elongation at fracture. © 2014 Elsevier B.V. All rights reserved.

Bacro J.-N.,Montpellier University | Bel L.,Agro ParisTech | Lantuejoul C.,MinesParisTech
Extremes | Year: 2010

Characterizing the behaviour of multivariate or spatial extreme values is of fundamental interest to understand how extreme events tend to occur. In this paper we propose to test for the asymptotic independence of bivariate maxima vectors. Our test statistic is derived from a madogram, a notion classically used in geostatistics to capture spatial structures. The test can be applied to bivariate vectors, and a generalization to the spatial context is proposed. For bivariate vectors, a comparison to the test by Falk and Michel (Ann Inst Stat Math 58:261-290, 2006) is conducted through a simulation study. In the spatial case, special attention is paid to pairwise dependence. A multiple test procedure is designed to determine at which lag asymptotic independence takes place. This new procedure is based on the bootstrap distribution of the number of times the null hypothesis is rejected. It is then tested on maxima of three classical spatial models and finally applied to two climate datasets. © Springer Science+Business Media, LLC 2010.

De Menibus A.H.,CEA Saclay Nuclear Research Center | Auzoux Q.,CEA Saclay Nuclear Research Center | Besson J.,MinesParistech | Crepin J.,MinesParistech
LWR Fuel Performance Meeting, Top Fuel 2013 | Year: 2013

This work is part of the global research effort carried out at the CEA to improve the understanding of zirconium based cladding tube failure under fast reactivity initiated accident (RIA) conditions, ie Rod Ejection Accident (REA) in Pressurized Water Reactors. It is focused on the impact of REA representative strain rates (about 1/s) on the fracture of unirradiated cold worked stress relieved Zircaloy-4.

Hellouin De Menibus A.,CEA Saclay Nuclear Research Center | Auzoux Q.,CEA Saclay Nuclear Research Center | Dieye O.,CEA Saclay Nuclear Research Center | Macdonald V.,CEA Saclay Nuclear Research Center | And 4 more authors.
LWR Fuel Performance Meeting, Top Fuel 2013 | Year: 2013

This work is part of the global research effort carried out at the CEA to improve the understanding of zirconium based cladding failure under rapid Reactivity Initiated Accident (RIA) transients. The present study is focused on the combined role of hydride blisters and loading biaxiality on the fracture of unirradiated cold worked stress relieved Zircaloy-4 cladding tubes.

Lantuejoul C.,MinesParisTech
Image Analysis and Stereology | Year: 2013

A Boolean model is a union of independent objects (compact random subsets) located at Poisson points. Two algorithms are proposed for simulating a Boolean model with non uniformly bounded objects in a bounded domain. The first one applies only to stationary models. It generates the objects prior to their Poisson locations. Two examples illustrate its applicability. The second algorithm applies to stationary and non-stationary models. It generates the Poisson points prior to the objects. Its practical difficulties of implementation are discussed. Both algorithms are based on importance sampling techniques, and the generated objects are weighted.

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