In the framework of reducing energy losses and of improving eco-efficiency, the Lumiere project aims to better understand and model the mechanisms governing the mixed lubrication regime with the objective of a more accurate estimate of the lifetime and friction losses of the lubricated components. Among the many facets of this problem, the impact of wear particles and their interactions with the lubricating fluid and the surfaces will be more particularly studied: by in situ observations on dedicated test benches and by the method of discrete elements (DEM) coupled with a lubrication model. The results will then be integrated into a multiscale tool allowing simulations at the component level. The work will be carried out by the Pprime Institute, specialized in the study and simulation of lubrication in collaboration with the LaMCoS, recognized for its skills in the experimental study of tribology and the LMGC, expert in the simulation of contact and wear by DEM.

Seismic faults are the places where earthquakes happen, by a sudden release of the stress accumulated in the surrounding rock, sometimes with dramatic consequences. The fault then starts sliding, and numerous thermo-mechanical phenomena occur within this interface.The DRAMA project aims to improve our understanding of these phenomena, by reproducing in the lab the conditions of seismic sliding of a fault rock asperity. The question is to determine under which conditions this asperity will melt (thus lubricating the fault and enhancing sliding) or abrade (thus releasing in the interface a granular fault gouge which will modify its frictional properties). Several instrumentational means will be used to describe and quantify the energetic budget at the scale of the asperity, and a novel and complex numerical model will be used to reproduce experiments and build a local asperity frictional law.

Medical implants replace dysfunctional or missing body parts to maintain physiological functions. The associated market is growing by 4%/year. However, the key factor restraining the market is high implant costs. In this view, PEEK and CRF-PEEK due to biocompatibility, mechanical properties similar to that of bone and radiolucency, are increasingly used instead of metals. But, these biomaterials are bionert inducing a very limited osseointegration, which is THE expectation for bone implants. Another expected properties are wear resistance, angiogenic ability and bacterio resistance. Ca-PEEK project is aiming at developing the next generation of PEEK implants that will provide answers to these expectations. For that, the PEEK surface will be modified with an adherent functionalized biomimetic apatite deposited by cold spray. The challenges are adhesion of the coating, maintaining the bioactivity of biomimetic apatite as a coating, preserving the mechanical properties of PEEK, enhancing the whole durability of the implant, and achieving multifunctionalization of the coating.

Continuous fiber reinforced composites (CFRP) are used to provide light weight and high performance. Among the possible reinforcements, NCF (Non Crimp Fabric) provides an interesting solution and are increasingly used for highly loaded structures. The fibres are straight and bonded together by stitches that can be adapted. Nevertheless, the forming of these NCFs is delicate. The deformation mechanisms involved are specific and there are few reliable approaches to simulating the forming process. The classical Cauchy mechanical models used for forming simulation are not able to simultaneously express the almost inextensibility of the fibres, the slippage between the fibres and the stitches and the bending stiffness of the fibres. The objective of this project is to develop simulation approaches that takes these different points into account using generalized continuous media models. To model the cases where gapping between the yarns will be possible, mesoscopic models will be constructed. Mechanical tests, at the yarn and reinforcement level, will be carried out to identify the models implemented in the simulations and in particular the generalized continuous environment models. Experimental forming tests on preforms of complex shapes will validate the draping simulations.

Most of our daily interactions with the environment are based on tactile exploration (e.g., with objects or the surface supporting the feet). Tactile perception relies on the stimulation of skin receptors and on the processing of the evoked response in the brain. Up to now, a few research has been devoted to uncover the cascade of the whole “perception chain”, i.e., from the mechanical stimuli, through the signal conversion and transmission, up to the higher-order neural processes related to the interaction of the body part with the surface. Intriguingly, most of the investigations in the field of sensorimotor control has ignored the mechanical characteristics of the surface in contact with the body and, inversely, most of the research in the field of engineering and mechanics of surfaces (or fabrics) have ignored the brain mechanisms involved in the processing of the peripheral tactile inputs. The aim of this project is to understand the perceptual outcomes of touch.