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Photo du rédacteurGoustan BACQUAERT

An industrial PhD: Balancing creativity and feasibility within a constrained environment


Goustan BACQUAERT
Goustan BACQUAERT

Merci beaucoup d'avoir accepté l'interview


Can you please describe your student journey until your start of PhD?

In 2016, I joined the École Nationale des Ponts et Chaussées after completing my preparatory classes in Angers and Nantes. I specialized then in solid mechanics and materials science. During my gap year, I completed several internships in industrial research and academic laboratories, in Paris, Munich, and Tokyo. These experiences encouraged my wish to continue with research activities. In my final year of engineering school in 2019, I decided to pursue thus, in parallel, the Master's program in Multiscale Analysis for Materials and Structures, jointly taught by the École Nationale des Ponts et Chaussées and Sorbonne University. It was during this program that I met the team who would later become my PhD advisors!

 

Can you please briefly describe your PhD thesis work?

First, this CIFRE PhD thesis was conducted in collaboration with EDF, the Institut Jean le Rond d’Alembert, and the Navier Laboratory. The target applications focused on studying the hydraulic structures of EDF, through numerical simulations using the finite element software Code_Aster. The goal was to certify their mechanical integrity under various static loads and seismic conditions.

More specifically, the first aspect of my work involved developing a constitutive model for granular soils, adopting a sound thermodynamic formulation. This began with revisiting traditional approaches to modeling granular soils within the framework of Generalized Standard Materials. Starting from a simple phenomenological law, we integrated relevant modeling elements such as nonlinear elasticity and hardening behaviors, aiming to achieve an optimal balance between robustness and accurate physical representation.

The second focus of the thesis was the study of regularization methods for strain localization, a characteristic phenomenon in the behavior of geomaterials. To address this, we concentrated on using the Generalized Standard Materials framework with internal variable gradients, which offers the advantage of a variational structure. This approach, supported by both analytical solutions and numerical results, proved effective. Numerical applications on structures demonstrateted the versatility of this regularization approach, as well as its relevance for addressing soil modeling challenges encountered at EDF.

 

In terms of personal values, what did your PhD journey add?

This thesis was first and foremost a collective journey, shared with my advisors and colleagues (but also my friends!). To synthesize the perspectives of both the industrial and academic viewpoints, I had to develop strong listening skills and a collaborative mindset. By fostering teamwork in this way, I was able to gain autonomy in my work, allowing me to address the final challenges posed by this CIFRE PhD thesis while following a path that aligned with my own scientific interests.

 

What are you currently working on?

For the past year, I have been working at EDF R&D as a research engineer, maintaining strong ties to my PhD activities. Part of my time remains dedicated to modeling the behavior of hydraulic structures. Additionally, my work now also focuses on the analysis of underground geotechnical structures, particularly in connection with the French deep geological repository for radioactive waste (Cigéo). Through these projects, I have been able to expand my technical expertise, building on the skills I developed during my education and PhD, particularly in rock mechanics, poromechanics, and related fields. This progression allows me to envision a career path within EDF R&D's expertise division.

 

Any advice for students who want to do PhD?

I believe it is essential for any student considering a PhD to begin with a mindset free from excessive certainties. Throughout the PhD journey, these certainties will be continuously challenged, often requiring you to question the quality and validity of the work you propose.

A second piece of advice I would offer is to take your time. With three years to complete a PhD, there is no need to place undue pressure on yourself to achieve results too quickly. Instead, focus on fully assimilating the fundamentals of your subject and meticulously verifying and refining your work. This approach ensures that the thesis outcomes not only provide a solid foundation for other future research but also inspire further PhD candidates

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