PhD Student (M/F) in Mechanics and Tribology of Multilayer Materials for Flooring Applications

Job Description

Thesis Subject

Floor coverings under real-life operating conditions (hospitals, schools, hotels, offices, retail environments, etc.) are subjected to diverse and repeated mechanical solicitations: rolling loads, particle abrasion, furniture movement, cleaning procedures, etc. These stresses generate a wide range of surface damage, reducing the visual appeal of the flooring and progressively leading to the need for replacement. Over recent years, Tarkett, a world leader in the field of floor coverings and a project partner, has collected operational feedback from various flooring systems installed in different target environments, allowing several types of surface degradation to be identified. Among all observed defects, scratches, abrasive wear, and gloss loss are the most significant. Despite several decades of industrial testing and the existence of numerous standards, no existing laboratory method can reliably reproduce the long-term degradation observed under real-life conditions. The industry relies on accelerated ageing tests (such as Martindale or Taber tests), which aim to compress several years of wear into a limited number of test cycles. In some cases, these methods even induce damage mechanisms that differ from those observed during long-term use. This highlights the limitations of current acceleration factors and the need to develop a mechanistic understanding of the phenomena rather than relying on simple empirical extrapolation.
The project objectives aim to address several major gaps: • Lack of correlation between laboratory tests and real-life ageing. Current tests do not reproduce the combined wear mechanisms occurring in service. The first objective of the project is to identify the laboratory tests that are most representative of real usage conditions and to develop hybrid protocols that more accurately reproduce in-service degradation. • Limited understanding of multilayer interactions. Floor coverings are composed of polyurethane layers exhibiting different mechanical behaviours. However, their yield stresses, stress flow mechanisms, relaxation and recovery behaviours, as well as the interfacial toughness and respective contributions of each layer to the overall behaviour, remain poorly characterised. The second objective of the thesis is to establish a multiscale mechanical map of these interactions. • Lack of a mechanistic database on real wear. Decades of field observations collected by Tarkett have never been structured from a scientific perspective. The third objective is to classify and quantify the observed defects and to correlate them with the product usage class and age.• Material design remains empirical rather than physics-based. Current optimisation strategies rely mainly on trial-and-error approaches. The fourth objective is to guide the selection of layers, their sequencing, and the overall system design by using finite element modelling (FEM) and machine learning (ML) tools.

Your Work Environment

The PhD project will be carried out at the Charles Sadron Institute (ICS, UPR 22 CNRS), located on the CNRS Cronenbourg campus in Strasbourg. The ICS is an internationally recognised research laboratory specialising in polymer science, multifunctional materials, materials mechanics, and interfacial phenomena. The PhD student (M/F) will join the Mechanics of Interfaces and Multiphase Systems (MIM) research group, whose activities focus on polymer and composite mechanics, tribology, contact mechanics, instrumented indentation, material damage mechanisms, and the durability of multilayer systems. The project is part of a close collaboration with Tarkett, a world-leading company in the field of innovative and sustainable flooring solutions. This collaboration provides a particularly attractive research environment at the interface between academic research and concrete industrial challenges. The PhD student will have access to state-of-the-art experimental facilities both at ICS and at Tarkett's R&D site in Wiltz (Luxembourg), enabling the preparation of multilayer samples, the implementation of advanced mechanical and tribological tests, and the validation of scratch and wear mechanisms under conditions representative of industrial applications. The project organisation will rely on regular interactions between the partners. The PhD student will spend significant periods at the Tarkett site (at least 25% of the PhD duration) to participate in sample preparation, experimental campaigns, and scientific discussions with research and development teams. Regular coordination meetings between academic and industrial supervisors will be organised, together with continuous sharing of experimental data and modelling results. The position is based in Strasbourg, a dynamic and international university city offering an attractive living environment, an efficient public transportation network, and a particularly rich scientific ecosystem. The candidate (M/F) will benefit from the advantages associated with the status of CNRS contractual staff, including access to a subsidised administrative restaurant and partial reimbursement of transportation costs. Remote working opportunities may be considered in accordance with applicable regulations and the requirements of the research project. This PhD project represents a unique opportunity to develop expertise at the interface between materials mechanics, tribology, and polymer engineering, within an environment strongly focused on innovation and the transfer of research outcomes towards concrete industrial applications.

Constraints and risks

The PhD project will be affiliated with the Doctoral School of Physics and Physical Chemistry (ED 182) of the University of Strasbourg. The PhD student (M/F) will be responsible for completing the administrative procedures associated with doctoral enrolment and for following the doctoral training programme (mandatory courses, individual monitoring committees, annual re-enrolments, etc.). As part of the partnership with Tarkett, regular visits to Tarkett's R&D site in Wiltz (Luxembourg) will be required, representing approximately 25% of the PhD duration. These missions will be funded by the company. Occasional travels in France or abroad to attend scientific conferences may also be planned during the PhD.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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