Thèse Vers une Modélisation Avancée de la Propagation des Fissures dans les Matériaux Anisotropes Grâce à la Fabrication Additive par Dépôt de Fil Fondu H/F

Doctorat.Gouv.Fr

Anisotropic materials gain importance in industry driven by new applications and environmental concerns, from wood construction, single crystals for photovoltaic applications or aerospace turbines, to Additive Manufactured materials. But due to the lack of certified damage tolerance models to guarantee their resistance to failure, their use in sensitive components whose failure must be avoided at all costs is limited.
Several funded projects aiming to fill this gap are currently in progress whithin our multi-disciplinary team. The thrust of these projects is to take advantage of the versatility of fused filament fabrication to design experiments that challenge advanced experimental and numerical approaches to fracture mechanics. Experimentally, advanced measurement techniques from Digital Image Correlation to state-of-the-art Digital Volume Correlation approaches are challenged. Numerically, concepts of linear elastic fracture mechanics, from the classical Griffith variational energy approach to phase-field simulations developed for anisotropic materials, are tested.
In this context, the thesis will focus on the development of innovative experiments based on the propagation of cracks in polycarbonate brittle materials printed by Fused Deposit Modeling in line with a previous PhD thesis. The design of experiments will be guided by human intelligence with artificial intelligence.

ANR 3FAM: Crack propagation in Anisotropic Materials manufactured by Fused Filament Fabrication processes (experiments and modelling)

Abstract: Due to the directional building process, additive manufacturing generally leads to anisotropic microstructures that highly influence crack propagation paths. It is thus crucial to be able
to take this directionality into account in damage tolerance approaches. This is even essential to extend the use of additive manufacturing to sensitive components, for instance, in the
field of aeronautics or aerospace where catastrophic failure has to be avoided at all costs. In this project, a first step toward this goal is aimed for in the framework of Linear Elastic
Fracture Mechanics, by focusing on Fused Filament Fabrication processes. As general models are sought, the processes for printing polymers by Fused Deposition Modeling, and
metals by Markforged will be considered. State-of-the-art experimental and numerical methods, together with an interdisciplinary mechanics-physics point of view, will be geared
toward (i) a deep and multi-scale understanding of the physical phenomena at play, and (ii) the development of safe, experimentally validated, mechanical methods to accurately
predict crack propagation from fatigue to brittle fracture threshold. The methodology will involve advanced and innovative tools, notably new fracture experiments carried out in-situ
in an XRay scanner, analyzed by Digital Volume Correlation in conjunction with multiscale asymptotic approaches and phase-field simulations. The expected benefits are to provide
tools to develop lighter, while safe, additively manufactured components, but also to elaborate damage tolerance approaches applying to a broad range of anisotropic materials, going
from 3D printed components to monocrystals in airplane engine components.

Setup new experiments to understand and predict how and when a crack propagates in an anisotropic material

New experiments will be designed using both human and artificial intelligence.
First, an extensive experimental campaign, varying the microstructure and shape of the sample under both monotonic and cyclic loading will be done.
Second, the experiments will be simulated using classical sharp crack approaches based on the Stress Intensity Factors, and phase-field models.
Third, comparison between experiments and simulations will aim to improve, calibrate and validate the models.