PhD student: Surface integrity generated during the belt finishing process and consequences on the lifetime of gear boxes shafts for automotive applications

Background :
The improvement of vehicles safety is an EU priority. The enhancement of the components performance reduces the likelihood of accidents caused by failures of these components. The FATECO project aims the fatigue and tribological performance improvement of automotive transmission parts by means of an optimized surface integrity reached through innovative finishing techniques. Additionally, some of these techniques will allow the lubricant removal, leading to a 100% eco-friendly process. This project is in collaboration with the research centre of FIAT in Turin and the research centre of SIDENOR in Bilbao.

Aim of the thesis :
-Understand and model the physical phenomena governing the surface integrity generation (and especially the surface topography) during the belt finishing process.
-Understand and model the surface influence on the functionality of gear boxes shafts (fatigue and wear).
For that, sensitivity experimental studies will be performed by varying the process parameters (belt abrasives, roller hardness, finishing time, contact forces etc…) and the surface integrity response will be observed (different roughness parameters, residual stresses…). Those observations will lead to the modelling of the surface generated by the process. It will take into account the process kinematic, abrasives/surface contact among others.
In a second time, experimental studies will be performed to link the surface integrity to the fatigue (rotational bending) and wear performances. Phenomenological or physical models will then be developed. In future, the belt finishing process could be optimized in order to improve the functionality.

Workplace :
The Laboratory of Tribology and System Dynamics (LTDS) is a research laboratory shared between the French national research council CNRS, École Centrale de Lyon, École Nationale d’Ingénieurs de Saint-Etienne (ENISE) and École Nationale des Travaux Publics de l’État. It is therefore located in 2 cities: Lyon and Saint-Étienne. The work placement will be in Saint-Etienne (60 km from Lyon). On this site, the MMP team (Material Mechanic and Processes) of LTDS owns a well-known expertise on manufacturing processes for aeronautic, automotive and nuclear industries. This expertise concerns:
-New metal additive manufacturing processes
-High performance machining processes
-Superfinishing processes (honing, belt finishing, grinding, drag finishing etc…)
In total, LTDS is composed of 62 professors and assistant professors, 23 researchers, 46 engineers and technicians, 169 PhD students and postdoctoral fellows. Concerning the MMP team, it is composed of 23 professors and assistant professors, 10 engineers and technicians, 30 PhD students and postdoctoral fellows.