PhD defense of S. Florez

The PhD defense will take place in CEMEF Mines ParisTech the 30th of November. These PhD works are dedicated to « Towards highly efficient massive-multidomain simulations in the context of microstructural evolutions ».

A brief summary below:

Strategic industries make extensive use of metallic materials. Today, there is a strong demand from these industries to predict, during hot metal forming processes, the microstructural evolutions of these materials, which are of prime importance concerning their final in-use properties.

In this context of massive multi-domain problems, numerous full-field approaches that describe grain boundary (GB) network motion at the mesoscopic scale have been developed for forty years. When very large deformations are investigated, as in the context of realistic industrial thermomechanical treatments, the level-set (LS) approach in the context of finite element (FE) formulations and meshing/remeshing algorithms remains the most powerful and versatile numerical tool.

Even if recent improvements were realized (context of DIGIMU software), the main weakness of this approach remains its numerical cost, which limits the number of grains considered (small representative volume elements) and still implies long calculation times, especially in 3D.

In these works, the performance of FE-LS models is studied and a new method denominated ToRealMotion, capable to perform 2D massive multi-domain simulations is introduced. This new method, belonging to the family of front-tracking methods, includes various innovations and has been parallelized. Geometrical properties used in the kinetics are only computed at the interfaces, and GBs migration is defined thanks to a Lagrangian scheme, keeping a FE discretization of the bulk of the grains through the concept of body-fitted unstructured FE meshes. This aspect allows for higher adaptability than traditional Front-Tracking models. Of course, one of the main ambitions of this new approach is the improvement of the computational performance when simulating evolving microstructures, while keeping the precision and versatility of the FE-LS approach. As such, 2D numerical cases in the context of grain growth (GG) and recrystallization (ReX) are provided to prove the efficiency of this new approach. These results show impressive reductions in the computational costs and offer promising perspectives on the modeling of massive multi-domain simulations in terms of numerical performance and precision in the modeling of numerous solid-state phenomena.

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