Missions

At the CNRS Futuroscope site, the Pprime Institute is recruiting a Researcher whose job will consist in continuing the collaboration initiated between the ENDO team and CETIM since 2009, and more specifically on aspects of rapid decompression on elastomer O-rings.

In addition to the various studies already carried out and the different items to be tackled, it seemed appropriate to :
- Complete the metrology by designing a system for simultaneous in-situ measurement of mass and strain. The aim is to identify solubility diffusion coefficients synchronized with swelling and temperature variation,
- To develop an ABAQUS user subroutine for diffuso-thermomechanical analysis, taking into account concentration, temperature and stress fields, both in experiments and in service,
- Conduct rapid decompression tests (RGD) to identify the parameters influencing damage, by considering different configurations,
- Work on the formulation of an initiation criterion based on thermodynamic concepts.

Activities

The candidate will carry out the following activities during this 24-month project:
- System design,
- Development of an Abaqus user subroutine,
- Experimental testing.

Skills

The candidate will have to possess the following skills:
- Solid knowledge of mechanics of materials and structural design,
- Skills in mechanical testing and programming,

The profile required is as follows:
-Trained as a mechanical engineer or Master's degree in Mechanics, followed by a PhD with a focus on mechanics of materials, with a strong taste for both experimental and numerical approaches.
-Fluency in English is essential, and a good knowledge of design would be a definite asset.

Work Context

This project is part of CETIM's collaboration with the Institut Pprime, which has been active for over 15 years, and focuses on characterizing the behavior of elastomers used for seals in an environment made up of diffusive species. In this context, extensive work has been carried out to identify thermo-diffusive-mechanical couplings, and today it seems appropriate to complete this knowledge on the evolution of the behavior of CO2-saturated HNBR under several phases (liquid-gas) and to study the rapid decompression phase (desorption phase).
The aim is to master these multiphysical couplings as effectively as possible, so as to be able to assess the seals' performance under pressure and over time. Fundamental questions concerning the state of the dissolved species within the rubber are being asked to better understand the damage-creating mechanism during a rapid drop in pressure. This phenomenon is a major limitation for seals.
Improved knowledge of behavior is also essential to develop a numerical model coupling hyperelasticity with temperature and CO2 diffusion. This is an essential tool for gaining a detailed understanding of the state of stress in joints during these transient phases, and for gaining a better grasp of the onset and evolution of damage. Based on these results, an initiation criterion will be proposed.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

Short-term travel in France and abroad is to be expected.