Post-Doc: Measurement of in-situ contact damage by X-ray tomography

14 Nov 2023
Job Information

Organisation/Company

LMPS – CNRS – CentraleSupélec – ENS Paris-Saclay

Research Field

Engineering » Mechanical engineering
Engineering » Materials engineering

Researcher Profile

Recognised Researcher (R2)

Country

France

Application Deadline

13 Dec 2023 – 23:00 (Europe/Paris)

Type of Contract

Temporary

Job Status

Full-time

Hours Per Week

35

Offer Starting Date

5 Feb 2024

Is the job funded through the EU Research Framework Programme?

Not funded by an EU programme

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

Keywords: Fretting, Contact, X-ray tomography, Image correlation, Quantitative imaging

 Mechanical assemblies subjected to vibration generate micro-friction at contact points. This stress, known as fretting, can lead to cracking and/or wear, reducing the service life of assemblies [1]. Many models exist to predict contact life, but there is still significant room for improvement. Most models use a continuous, homogeneous interface, whereas the actual contact air, pressure distribution and friction coefficient depend on the local state of the contact [2-5]. When this information is considered, it is generally calibrated on observations made before and after the test [6,7]. Performing an in-situ fretting test using tomography would give access to both the location and shape of the damage in 3D, yet this damage modifies the local stiffness of the contact, creating a strong coupling between damage and mechanics. The LMPS has recently designed such a device (Figure 1), but its use remains to be developed.

The aim of this post-doctoral work is to develop a method for quantifying local information (friction, stiffness, slip, etc.) in a fretting contact during 4D loading using this in-situ fretting device under laboratory X-ray tomography. This study will be carried out on a 2000 series aluminum model material with a cylinder/plane type contact.

The first step will be to validate the assembly against the fretting vibration test under controlled load, with a large number of cycles. The damage generated will be compared with that obtained on a conventional test bench. The second stage will involve setting up in-situ test protocols. The third stage will involve setting up analysis tools combining X-ray tomography with integrated digital image correlation to measure relative displacements between the cylinder and the plane. This approach enables accurate estimation of deformation fields using volume image correlation from in-situ testing, together with finite element simulation including appropriate material laws and cracks (Zmat/Zcracks).

The tests carried out as part of this project will provide the first in situ images of a fretting contact. Quantifying the 4D evolution of a fretting contact will be a new advance in the field. At the end of the project, we’ll have a digital twin that perfectly represents the geometries in contact, enabling us to test different friction models (Figure 2). The results will enable us to gain a better understanding of contact tribology, and to discuss friction models and the need or otherwise for discretization in time and space.

Profile sought: PhD in mechanics of materials with experience in image correlation or experimental mechanics. Interest in test-calculation dialogue.
Duration: 12 months as soon as possible
Location: Laboratory of Mechanics Paris-Saclay (LMPS, CentraleSupélec, ENS Paris-Saclay), Gif-sur-Yvette. Travel to Centre des Matériaux (CdM) of Mines Paris, Evry.

[1] Waterhouse, RB 1. (1992) Int. materials reviews, 37.1, 77-98.
[2] Bhatti, N. A., & Wahab, M. A. (2018). Trib. Int., 121, 121-138. 
[3] Vakis, A. I., et al. (2018). Trib. Int., 125, 169-199.                     
[4] Cheikh, M., et al. (2007). Wear, 262(7-8), 914-924.
[5] Murthy, H., & Vadivuchezhian, K. (2017). Trib. Int., 108, 164-173.
[6] Prouchon et al. (2005). Int. J. of Fat., 27, 569-579 
[7] Brink et al. (2021).  J. Mech. Phys. Solids, 147, 104238

Requirements

Research Field

Engineering » Materials engineering

Education Level

PhD or equivalent

Research Field

Engineering » Mechanical engineering

Education Level

PhD or equivalent

Skills/Qualifications

PhD in mechanics of materials with experience in image correlation or experimental mechanics. Interest in test-calculation dialogue

Languages

ENGLISH

Level

Good

Research Field

Engineering » Materials engineeringEngineering » Mechanical engineering

Years of Research Experience

1 – 4

Additional Information
Work Location(s)

Number of offers available

1

Company/Institute

LMPS – CNRS – CentraleSupélec – ENS Paris-Saclay

Country

France

City

Gif Sur Yvette

Postal Code

91190

Street

3 rue joliot curie

Number of offers available

1

Company/Institute

Centre des Matériaux

Country

France

City

Corbeil-Essonnes

Postal Code

91100

Street

63-65 Rue Henri Auguste Desbruères

Where to apply

E-mail

[email protected]

Contact

City

Gif sur Yvette

Website

https://lmps.ens-paris-saclay.fr/en

Street

rue joliot Curie

Postal Code

91190

STATUS: EXPIRED