SOFITT

The present proposal addresses an emerging activity dealing with a new lubrication mechanism of biomimetic inspiration, called eX-Poro-HydroDynamic (XPHD) lubrication. It consists of self-sustained fluid films generated within compressible porous layers imbibed with liquids and subjected to external normal or tangential forces. The objective is to find innovative technical solutions that break with current practices, offering efficient turbomachinery guidance and support systems in terms of load capacity, damping, reliability, friction and environmental impact. The project aims to demonstrate industrial applications and to develop numerical tools capable of predicting the operating behavior of these new technologies. The scientific target deals with challenges stem from the coupling of multiple mechanisms being intrinsically inter- and multi-disciplinary. The project is at the interface of several scientific fields: solid mechanics, fluid mechanics and thermal engineering. It calls on multidisciplinary skills in experimental mechanics and numerical analysis. The knowledge acquired in this project can be used not only to find innovative technical solutions in turbomachinery but, in the longer term, can also be applied to studies dedicated to biological tissues or to human joints where the behavior of soaked porous materials (human cartilage) is also a key point. To achieve the objective, the project relies on the scientific and experimental expertise of three research teams covering the fields of tribology, photomechanics and modelling of fluid-structure interaction. It is organized into three scientific WorkPackages. The main objective of the first scientific WorkPackage is to understand the mechanical behavior of the porous complex structures (combination of a solid deformable structure with a high porosity, soaked with fluid), linked to microstructural properties of the solid material and interactions with the fluid. The work will be carried out in three steps intended to decouple the physical effects in order to facilitate the understanding of physical phenomena: quasi-static 3D investigation, dynamic investigation on 2D simplified sample and global dynamic characterization in terms of rigidity and damping. The experimental data acquired will serve as input parameters for the second scientific WorkPackage, dedicated to the development of two numerical models aiming to study the response to external stresses of liquid-soaked porous materials, in particular by estimating their elastic response and damping capacity. A first task will be dedicated to the simulation at the microscopic scale of the flow through the structure of porous compressible materials. A second task proposes, on a larger scale, the development of a mechanical behavior model to predict the macroscale response, in particular the fluid/structure interaction. The third scientific WorkPackage will use the experimental and numerical results obtained in the first two WorkPackages to design two lubricated elements: a thrust bearing and a squeeze damper. The work will be divided into three tasks. A first task proposes experimental studies on guidance systems supporting static axial load. A second task also deals with experimental aspects by testing the damping capacity of XPHD solutions in the presence of an unbalance. The third task concerns the development of numerical simulation models on the scale of XPHD components. Two additional WorkPackages will be respectively devoted to the management and to the capitalization and dissemination of the project findings.