At IRDL, Xavier Colon explored the behavior of mild steels under large deformations to optimize automotive manufacturing.
Xavier Colon, chercheur·e au sein de IRDL (Institut National Polytechnique de Bretagne).
Thèse soutenue en 2025 à l'école doctorale École doctorale Sciences Pour l'Ingénieur (Lorient ; 2022-....).
Référencée dans le réseau ABES/STAR, cette thèse répond aux critères de rigueur de l'enseignement supérieur français.
The automotive industry is at a decisive turning point. As the transition to electric vehicles accelerates, the manufacturing of the bodies of these vehicles still relies on traditional techniques for assembling metal sheets, often considered obsolete in a world seeking sustainability. Xavier Colon's thesis, conducted at IRDL, highlights the importance of understanding the behavior of metallic materials, particularly mild steel, subjected to significant deformations. This research is of crucial relevance for optimizing manufacturing processes, especially in a context where sustainability and resource efficiency are paramount.
In a rapidly changing automotive market, where environmental issues take center stage, it becomes essential to reassess the materials used. Mild steel, although a traditional choice, presents characteristics that can be optimized through a better understanding of its behavior under deformation. Indeed, Colon's research is part of an approach aimed at improving not only vehicle performance but also reducing their ecological footprint.
The experimental devices developed by Colon, namely the plane torsion test and the simple shear test, allow for the analysis of anisotropy and material history effects. These tests provide valuable data on how mild steels react under different stresses, which is essential for calibrating damage accumulation models. For example, anisotropy can influence how a material deforms in different directions, which is crucial during the shaping of sheets. Indeed, understanding linear and complex loading paths is fundamental to anticipating material performance during shaping or impact. This has direct implications for vehicle safety, as a material that deforms predictably can better absorb shocks in the event of an accident.
The results of this research pave the way for innovations in automotive structure design. By optimizing the amount of material used, it is possible to reduce vehicle weight, which contributes to improving their energy efficiency. For example, lighter vehicles require less energy to move, resulting in reduced greenhouse gas emissions. Furthermore, the innovation of sequential re-machining of the edges of the specimens allows for achieving large deformations while preserving the simplicity of the tests. This could transform the way materials are tested and used in the industry, making processes more efficient and less costly.
However, it is essential to ask questions about the practical application of these results. How can manufacturers integrate this new knowledge into their production processes? What challenges must be overcome for these innovations to be adopted on a large scale? The answers to these questions will determine the real impact of this research on the automotive industry and, by extension, on the environment. Companies must be ready to invest in technologies and training to leverage these advancements.
Moreover, it is important to consider the economic implications of these changes. The adoption of new manufacturing processes may require significant initial investments, but the savings achieved in the long term, both in terms of production costs and waste reduction, can offset these expenses. Policymakers must also take into account the impact on employment, as the evolution of manufacturing techniques may lead to changes in the required skills.
In summary, Xavier Colon's thesis is not limited to a simple academic study. It represents an opportunity for the automotive industry to rethink its manufacturing methods at the dawn of a new era. Decision-makers must consider these advancements to remain competitive and meet the growing demands for sustainability and efficiency. By integrating this new knowledge, the industry can not only improve its performance but also contribute to a more sustainable future for all.
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Sources et accès
Xavier Colon. Étude numérique et expérimentale du cisaillement d’un acier doux en grandes déformation : anisotropie, effet d'histoire et effet de la vitesse de déformation. Mécanique des matériaux [physics.class-ph]. Université de Bretagne Sud, 2025. Français. ⟨NNT : 2025LORIS729⟩. ⟨tel-05457085⟩