En poursuivant votre navigation sur ce site, vous acceptez le dépôt de cookies dans votre navigateur. (En savoir plus)

PhD Thesis M/W: Development of hybrid numerical methods for the diffraction of ultrasonic waves by obstacles on the surface of stratified structures, and application in Non-Destructive Testing

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : vendredi 26 août 2022

Assurez-vous que votre profil candidat soit correctement renseigné avant de postuler. Les informations de votre profil complètent celles associées à chaque candidature. Afin d’augmenter votre visibilité sur notre Portail Emploi et ainsi permettre aux recruteurs de consulter votre profil candidat, vous avez la possibilité de déposer votre CV dans notre CVThèque en un clic !

General information

Reference : UMR5295-ERIDUC-001
Workplace : TALENCE
Date of publication : Friday, August 5, 2022
Scientific Responsible name : Marc Deschamps, DR CNRS I2M-APy
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

The thesis deals with the numerical modeling of the generation, propagation and radiation of ultrasonic waves in stratified plane or cylindrical structures, including sensors, reinforcements and surface defects. Hybrid methods will be developed, combining a fast semi-analytical calculation of the propagation in the canonical structure and a treatment adapted to the diffracting objects: asymptotic model, or local numerical model and domain decomposition, depending on the case.
Detection of defects by NDT methods using ultrasonic waves is an important issue in many industrial fields. The improvement of these different methods often relies on the simulation of the wave propagation in the inspected structure. The hybrid modeling explored in the thesis will take into account the complexity of the structure, the role of the sensors and the presence of defects, by dealing with the diffraction of the waves by these obstacles.
Two hybridization methods with the TraFiC code (FFL method) of I2M will be developed to model the diffraction by objects of small dimensions compared to those of the structure.
The first one is the "asymptotic approximation" which allows to represent the diffracting behavior of an occlusion of small characteristic dimension located on the surface of the structure by one or several tensors. These tensors are calculated once and for all for a given occlusion geometry and a given layer material. In this case, any numerical modeling of Finite Element (FE) type is excluded.
The second is "domain decomposition", which has already been validated in many other contexts. It is an iterative approach that allows to independently carry out computations on several elements coupled by the boundary conditions at their common borders, whose satisfaction constitutes the convergence criterion of the iterative process. This approach has been originally intended to facilitate the parallelization of calculations. In the context of this thesis, it is intended to combine the semi-analytical modeling of the canonical structure (simulation by the TraFiC code of the propagation in the multilayer structure) and the numerical modeling of disturbances or local details (transducer or reinforcement in contact with the structure modeled by FE) by driving the respective solvers "from the outside".

Work Context

The three laboratories involved in this project are the CEA LIST (Saclay), the POEMS laboratory (ENSTA, Palaiseau) and the Institute of Mechanics and Engineering of Bordeaux (I2M, University of Bordeaux). These laboratories have recognized and complementary skills, which have led them to numerous collaborations over the years.
To achieve the objectives, the PhD student will work mainly at I2M but will also regularly visit the Saclay site (POEMS and CEA LIST). The computer development work for the development of the methods will take place in Bordeaux, as well as the design and realization of experimental validation devices. The more theoretical and mathematical aspects will require the presence of the PhD student in the POEMS laboratory. The development of the demonstrator will take place at CEA LIST.

Constraints and risks

This thesis is co-financed by the AID-DGA (Agence de l'Innovation de Défense de la Direction Générale de l'Armement, file number: 2022422) and the CEA LIST.

We talk about it on Twitter!