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Portail > Offres > Offre UMR5513-DAVDAL-002 - Post-Doctorat en physique et mécanique des contacts en matière molle (H/F)

Post-Doctoral position in physics and mechanics of soft matter(H/F)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : lundi 13 décembre 2021

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General information

Reference : UMR5513-DAVDAL-002
Workplace : ECULLY
Date of publication : Monday, November 22, 2021
Type of Contract : FTC Scientist
Contract Period : 24 months
Expected date of employment : 1 February 2022
Proportion of work : Full time
Remuneration : between 2750 and 3100 € brut/month
Desired level of education : PhD
Experience required : Indifferent

Missions

The WEEL project:
This post-doctoral project will be part of a broader collaborative project (acronym WEEL) between Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), Ingénierie des Matériaux Polymères (IMP) and Solvay Silica company, funded by the French National Agency for Research (ANR). The project aims at bringing new insights in the fundamental understanding of the abrasion wear mechanisms of reinforced elastomers that will set the basis for future improvement in the prediction of durability of such materials, and in particular car or truck tires. Understanding abrasion wear remains an unsolved scientific challenge, that we propose to tackle by combining for the first time (i) proper wear experiments with (ii) advanced experimental and numerical investigation of the in-operando stress/strain field at a sliding interface. Indeed, our main research hypothesis is that the latter mechanical fields are the true local driving forces responsible for wear evolution. Our strategy will thus be threefold:
1. preparation of various types of carefully controlled reinforced elastomer samples by Solvay company
2. use of a home-made wear test device to characterize the wear properties of those samples, including the evolutions of their shape and of the local wear patterns (ridges, rolls,…)
3. use of a recent, cutting-edge opto-mechanical device to analyse the contact stress/strain state and dynamics, at different stages of the wear evolution.
4. development of an improved, comprehensive model of wear of reinforced elastomers incorporating the local contact conditions.

The “contact mechanics” PhD project
While point 2 above will be carried out by another PhD student, point 3 is the focus of the present Post-Doctoral project. In recent years, the consortium developed an internationally recognized expertise in the contact mechanics of sheared elastomer contacts. Under increasing shear, those contacts undergo important changes in the average contact pressure and in the micro-contact morphology, even under constant normal loading [R. Sahli et al. PNAS 115, 471 (2018)]. Such changes are expected to affect all macroscopic responses of the interface, including wear. But, so far, those insights have not been correlated to the observed spatial patterns of wear in reinforced elastomers
The main experimental task of the candidate will be to perform single-loading-cycle tribo-tests with complex kinematics, on either pristine or previously worn samples from wear tests that will be performed by the consortium. He/she will measure not only the classical evolution of macroscopic normal and tangential forces but also that of the true contact area and interfacial stress/strain field at different stages during the wear process. Both latter quantities will be obtained through advanced analysis of in-situ contact images using particle tracking [J. Lengiewicz, et al. J. Mech. Phys. Solids 143, 104056 (2020)] or digital image correlation (DIC) [A. Prevost et al. Eur. Phys. J. E 36, 17 (2013)]. We will aim at extracting the local stress/strain state, at different scales, to understand both the global morphology of the wear scar and origin of the local conditions associated with different wear mechanisms.

Many experimental set-ups available in LTDS laboratory will be made available for this project. This includes in particular a world class, new generation opto-mechanical contact mechanics device. Many more facilities of the LTDS laboratory will be used for specific friction tests, sample characterization (microscopy (optical, SEM, AFM ...), camera, fast camera ...) or numerical modelling, among others. The Post-doc will be mainly located at LTDS (Ecole Centrale de Lyon -CNRS) very close to Lyon but will involve close collaborative work with other partners within the WEEL project (IMP and Solvay, both also very close to Lyon), specifically with the other PhD student dedicated to wear experiments.

Activities

The work will include an important experimental component: preparation / physico-chemical characterization of samples, their mechanical and optical characterization. It will also involve processing and analyzing a large amount of data, not only experimental but also digital. Finally, the doctoral student will have to synthesize these results, place them in the context of international literature and use them to write articles for international scientific journals. The work also includes participation in national or international congresses.

Skills

The candidate must hold an PhD degree in experimental physics or experimental mechanics. The position requires solid knowledge in tribology and contact mechanics, in particular elastomers. The following specific skills are not required but will be a plus:
- Practical experience with elastomers
- Practical experience in image analysis
- Ability to develop or modify an experimental device
A good command of at least one programming language (ideally Matlab) is necessary. A good command of English is required. Experience of at least 3 months in a non-French speaking country is highly desirable. Candidates must demonstrate excellent writing skills, and have demonstrated (internships for example) their ability to lead a scientific project. They should be able to work in an international and multidisciplinary team. A great deal of autonomy, a proven organizational capacity and a good capacity to report are expected. Candidates must show a high level of critical thinking, ease in scientific argumentation and the ability to take initiative. Applications should include a detailed CV; if possible two references (people likely to be contacted); a one-page cover letter; a one-page summary of the master's thesis or end of study thesis; Master 1 or 2 or engineering school grades).

Work Context

ThePost-doc will work within a multidisciplinary team of the LTDS including two supervisors (physicists), two engineers (one in surface sciences and one in instrumentation) and also in connection with the IMP laboratory.

Constraints and risks

Not applicable

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