The ninety-seventh UQSay seminar on UQ, DACE and related topics will take place online on Thursday afternoon, March 26, 2026.
2–3 PM — Anthony Quintin (CEA DIF)
Optimal experimental designs based on the cross-entropy method for planning fracture toughness tests
Nuclear reactor pressure vessels undergo progressive embrittlement under neutron irradiation, monitored through the Master Curve theory which estimates a reference temperature T0. The core challenge is obtaining a reliable estimate of T0 from a very limited number of specimens. The work pursues two objectives. First, developing a numerical twin of fracture toughness test campaigns based on finite element simulations coupled with a Beremin model calibrated via Bayesian inference. Second, building a decision-making tool to optimize experimental planning within the framework of Bayesian Optimal Experimental Design, which seeks to determine the experimental conditions maximizing the information gained from a limited number of observations.
To this end, the approach relies on a Bayesian optimization method aimed at identifying test temperature sequences that minimize uncertainty on T0. The problem is formulated as a constrained combinatorial optimization, where the criterion to maximize is an expected information gain (entropy). Temperature sequences are modeled as homogeneous first-order discrete-time Markov chains, whose transition matrix is optimized via the Cross-Entropy Method. The resulting method yields a transition matrix that serves as a directly interpretable sequential decision rule. The proposed methodology is inherently general and transferable to any material and to a broad range of experimental testing frameworks where observations are limited and acquisition costs are high.
References:
- Plans d'expériences d'essais optimaux, 2025
- Uncertainty quantification of the reference temperature T0 of 16MND5 steel from experimental and numerical fracture toughness tests, 2025
Joint work with Jean Marc Bourinet & Cécile Mattrand (SIGMA Clermont) & Rudy Chocat (CEA Saclay) & Tom Petit (CEA Gramat)
Organizing committee: Pierre Barbillon (MIA-Paris), Julien Bect (L2S), Nicolas Bousquet (EDF R&D), Vincent Chabridon (EDF R&D), Amélie Fau (LMPS), Filippo Gatti (LMPS), Clément Gauchy (CEA), Bertrand Iooss (EDF R&D), Alexandre Janon (LMO), Sidonie Lefebvre (ONERA), Didier Lucor (LISN), Sébastien Petit (LNE), Emmanuel Vazquez (L2S), Xujia Zhu (L2S).
Coordinators: Sidonie Lefebvre (ONERA) & Xujia Zhu (L2S)
Practical details: the seminar will be held online using Microsoft Teams.
If you want to attend this seminar (or any of the forthcoming online UQSay seminars), and if you do not already have access to the UQSay group on Teams, simply send an email and you will be invited. Please specify which email address the invitation must be sent to (this has to be the address associated with your Teams account).
You will find the link to the seminar on the "General" UQSay channel on Teams, approximately 15 minutes before the beginning.
The technical side of things: you can use Teams either directly from your web browser or using the "fat client", which is available for most platforms (Windows, Linux, Mac, Android & iOS). We strongly recommend the latter option whenever possible. Please give it a try before the seminar to anticipate potential problems.
