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theses
36 mois

BIOMIMETISM AND BIOINSPIRATION OF THE ANGUILLIFORM SWIM OF A SNAKE

The performance of aquatic locomotion is closely related to the circulation of the flow around the animal's body and primarily to the intensity of the induced flow downstream of the tail and its characteristics. This developing wake consists in a Von Karman street vortices whose vortices are periodically emitted with each flap of the tail. The way the tail moves in the fluid (angle of attack, amplitude, frequency ...) determines the swimming performance. Animals can adjust their swimming kinematics to optimize their performance. Different criteria can define performance, such as energy efficiency, maximum speed (prey-predator system), or even stealth. The shape of the body and the tribological properties of the skin, which influence the propulsion and drag produced by swimming animals, must be taken into account. The central objective of this thesis is to contribute to the development of a numerical model based on real data such as geometry, kinematics, skin texture (data-driven numerical modeling) in order to simulate the complex phenomena of unsteady fluid-structure interaction (FSI), involved in anguilliform swimming within an incompressible viscous flow in the presence of a free surface.The aim is to identify the hydrodynamic mechanisms that will allow us to obtain estimates of the efficiency of this swimming in terms of propulsive force and energy efficiency, based on the kinematic and velocimetric data that characterize the swimming of snakes. This thesis work is part of a larger ANR (Dragon II) project in which biologists, fluid mechanics, mathematicians and roboticists are involved. A strong link will be maintained with the experimentalists of the project and experimental data on the swimming of real snakes and bio-inspired robots will be made available in order to validate the numerical model. The candidate will be required to participate in measurement campaigns at the Ecole Supérieure de Physique et de Chimie Industrielles in Paris, at the PPRIME Institute in Poitiers and at the Center for Biological Studies in Chizé .
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3 years, from October 2024

MODIFIED ISPH METHOD FOR MODELING THE WAVES INTERACTION WITH THE COASTAL PROTECTION STRUCTURES

Coastalization refers to the dual process of increasing attractiveness of the coastline and the transformation of coastlines due to the intensification of human presence and activities, observable since the 1970s. Coastal erosion and submersion are risks associated with coastalization. To protect the coastline, defense structures have been built at high costs...
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36 months

PhD - Physical properties of functional thin films under mechanical stresses

The proposed thesis is part of an international collaborative research project (PRCI) of the ANR (French National Research Agency) and its Austrian alter ego the FWF (Fund zur Furderung der Wissenschaftlichen Forschung): NANOARCHITECTED FILMS FOR UNBREAKABLE FLEXIBLE ELECTRONICS (NANOFILM). The thesis aims to understand the relationship between the microstructure and the mechanical and electrical properties of nanostructured thin films using synchrotron radiation and X-ray diffraction supported by electrical characterization techniques such as Hall effect and Van der Pauw resistivity. The candidate will have the opportunity to participate in the design and production of a new biaxial traction machine of smaller dimensions than the one used in diffraction to visualize cracks under atomic force microscopy (AFM).
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36 months

[Filled] Surface hardening and fatigue behaviour of titanium alloys induced by multi-interstitial followed by mechanical surface treatments: effect of property gradient

This PhD offer has already been filled. The objective of our project is to open new routes to the improvement of the tribological properties of titanium alloys. To achieve this objective, a combination of thermochemical (multi-interstitial diffusion at moderate temperature) and mechanical (Surface Mechanical Attrition: SMAT) surface treatments will be considered. The underlying hypothesis of this research is that this combination will allow the formation of hard layers supported by a thick supporting layer with smooth mechanical property gradients together with the preservation of the macroscopic mechanical resistance of the alloys. Surface hardness will be used as an indicator for the treatment’s efficiency, and mechanical testing (including in situ tensile tests operated in SEM and fatigue testing) will be conducted to study the evolution of the damaging mechanisms of the material.
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