Description

Scientific and Industrial Challenges
Fretting fatigue phenomena are highly detrimental to the structural design of aeronautical components. These combined effects of fatigue and fretting (alternating micro-slips at the contact interfaces) accelerate both crack initiation and crack propagation processes. Such phenomena are observed in various aircraft structures, including turbofan engines and bolted or riveted wings.
While damage prediction for so-called non-conformal contacts (e.g. turbine blade roots) is now well mastered, the prediction of conformal contacts—such as bolted or riveted plate assemblies—remains much more challenging [1]. For these large conformal contacts (Fig. 1), it is necessary not only to simulate the mechanical loadings but also to account for local tribological phenomena known as Fretting Wear Spots, which promote the formation of Tribologically Transformed Structures (TTS) [2].
These TTS, although extremely hard, are also very brittle, thereby facilitating crack initiation. Consequently, unlike conventional approaches (which transpose multiaxial fatigue criteria while considering stress gradients), it is essential to develop a multiphysics approach integrating fatigue, tribology (fretting), and metallurgy (TTS formation) to address these scientific and technological issues. Within this framework, AIRBUS has established a CIFRE PhD collaboration with the Centre des Matériaux of Mines Paris – PSL.

PhD Programme
Following a comprehensive literature review, the PhD candidate will undertake a research stay at AIRBUS to accurately define the industrial problem and refine all relevant characteristics related to fretting fatigue in conformal contacts (contact configuration, loading conditions, materials, etc.). Based on this information, and in collaboration with CMAT engineers, a “fretting fatigue bending bonded assembly” test bench, inspired by the work of Mäntylä et al. [1], will be developed and instrumented using Digital Image Correlation (DIC) techniques (CMAT expertise) (Fig. 2). Unlike existing devices, this setup will allow for local measurement of fretting loads within the assembled plates. A series of experiments will then be conducted to study, as a function of loading conditions (bolt clamping force, bending load, and contact pressure), the fatigue life of TA6V assemblies, as well as the onset of Fretting Seizure Spots (FSS) and the formation of TTS. From these results, a multiphysics model—inspired by previous CMAT work [3–4]—will be developed.

This model will simulate not only the diffusion but also the consumption of oxygen at the fretted interface, in order to predict the appearance of Fretting Seizure Spots (under-oxygenated zones within the contact interface that prevent oxide formation and promote surface metal-metal seizure) as well as the formation of TTS. The resulting tribochemical model of fretting phenomena will be coupled with a multiaxial fatigue analysis to more reliably predict the fatigue life and crack propagation of assembled components [5]. In a first stage, the model will be calibrated using experimental data, and then extended to predict the risk of fretting-induced cracking in industrial assemblies (bonded assemblies). Finally, these developments (copy of the test rig & model) will be transferred to the AIRBUS R&D Centre, enabling the company to implement optimized design strategies and to select appropriate mitigation solutions (e.g., surface treatments).

Skills required

Typical profile for a thesis at MINES Paris: Engineer and / or Master of Science - Good level of general and scientific culture. Good level of knowledge of French (B2 level in french is required) and English. (B2 level in english is required) Good analytical, synthesis, innovation and communication skills. Qualities of adaptability and creativity. Teaching skills. Motivation for research activity. Coherent professional project. Prerequisite (specific skills for this thesis): Applicants should supply the following : • a detailed resume • a copy of the identity card or passport • a covering letter explaining the applicant’s motivation for the position • detailed exam results • two references : the name and contact details of at least two people who could be contacted • to provide an appreciation of the candidate • Your notes of M1, M2 • level of English equivalent TOEIC to be sent to recrutement_these@mat.mines-paristech.fr

Bibliography

[1] A. Mantyla, et al. Prediction of contact condition and surface damage by simulating variable friction coefficient and wear, Tribology International 143 (2020) 106054
[2] V. Lefranc, C. Gandiolle, M. Vallet, J. Bourgon, E. Héripré, S. Fouvry, V. Aubin, Scenario for the formation of fretting obtained TTS in TA6V from detailed microstructural analysis, Wear 571 (2025) 205834.
[3] S. Baydoun, P. Arnaud , S. Fouvry, Modelling adhesive wear extension in fretting interfaces: An advection-dispersion-reaction contact oxygenation approach, Trib.Int. 151 (2020) 106490
[4] P. Arnaud, S. Baydoun, S. Fouvry, Modeling adhesive and abrasive wear phenomena in fretting interfaces: A multiphysics approach coupling friction energy, third body and contact oxygenation concepts, Tribology International 161 (2021) 107077.
[5] P. Arnaud, S. Fouvry, Modeling the fretting fatigue endurance from partial to gross slip: The effect of debris layer, Tribology International 143, 2020, 106 069

Keywords

Fretting Fatigue, Cracking, Wear, TTS