Thermo-mechanical Modelling of Pebble Beds in Fusion Blankets and its Implementation by a Return-Mapping Algorithm
- IMF II, Forschungszentrum Karlsruhe, Karlsruhe (Germany)
In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. Reimann at Forschungszentrum Karlsruhe (FZK). The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered. Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importance with respect to the application of pebble beds in fusion blankets. Therefore, UMAT (user defined material's mechanical behaviour) and UMATHT (user defined material's thermal behaviour) routines are used to re-implement the present thermo-mechanical model in ABAQUS. An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature. Finally, the thermo-mechanical interactions are implemented in a UMATHT routine for the coupled analysis. The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made. (authors)
- Research Organization:
- Materials Research Society, 506 Keystone Drive, Warrendale, PA, 15086-7573 (United States)
- OSTI ID:
- 21091564
- Resource Relation:
- Conference: Symposium on Structural and Refractory Materials for Fusion and Fission Technologies, Boston, MA (United States), 28-30 Nov 2006; Other Information: Country of input: France; Related Information: In: Proceedings of the Symposium on Structural and Refractory Materials for Fusion and Fission Technologies, by Aktaa, J. [ed. Forschungszentrum Karlsruhe GmbH, Institute for Materials Research II, Postfach 3640, 76021 Karlsruhe (Germany)]; Samaras, M. [ed. Paul Scherrer Institute, Nuclear Energy and Safety, CH-5232 Villigen PSI (Switzerland)]; Serrano de Caro, M. [ed. Lawrence Livermore National Laboratory, Chemical Biology and Nuclear Science Division, L-632, P.O. Box 808, Livermore, CA 94550 (United States)]; Victoria, M. [ed. Polytechnic University of Madrid, Instituto de Fusion Nuclear, J. Gutierrez Abascal 2, 28006 Madrid (Spain)]; Wirth, B. [ed. University of California-Berkeley, Nuclear Engineering Dept., Berkeley, CA 94720-1730 (United States)], v. 981E, 112 pages.
- Country of Publication:
- United States
- Language:
- English
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