The study of frictional contacts, especially under extreme conditions of velocity, deformation or energy dissipation, is considered very difficult because of the numerous physical couplings involved, the scale interactions and the frequent complexity of the materials used. This type of problem is often approached from a particular point of view such as thermal, dynamic, materials, etc.
The research conducted within the µFrein group is remarkable for its systemic and multiphysics approach. On an international scale, the laboratory is one of the few capable of conducting studies at several scales: "tribological" at the contact scale, "materials" at the component scale and "structures" at the system scale. With 20 years of experience in the field, it is recognized for its work on the identification :
- physical coupling parameters of the system in contact (interactions between tribology - thermomechanics - dynamics),
- evolution mechanisms of materials and surfaces in relation with the solicitations, in realistic conditions of use
- vibratory instabilities induced by friction, in connection with the evolution of the system in contact (surfaces, materials, etc.)
To do this, µFrein brings together a wide range of complementary skills in tribology, thermomechanics, dynamics and physical chemistry. It has developed specific means :
- theoretical modeling,
- multi-scale numerical modeling,
- development of friction materials,
- analysis of surfaces and materials, coupled with identification of properties / behavior at relevant scales,
- tribological tests, representative of the use or dedicated (particular coupling, simplification of materials and surfaces, controlled environment, etc.), mainly developed in-house,
- thermal, dynamic and tribological instrumentation, including some original instruments (bichromatic thermography) and especially coupled with inverse identification methods.
The dialogue between model and experiment is encouraged, as it is essential for the instrumentation of the contact that is inaccessible by experiment and for the identification of the key factors of the model.
The applications are mainly in the field of transport, in relation to the safety of organs, the durability of materials, the reduction of energy consumption and environmental and public health nuisances (noise emissions and particulate emissions).
The main applications are braking (SNCF, FLERTEX, CBI, Nipon Steel & Sumitomo Metal (jp), ...), wheel-rail contact (RATP, MG-VALDUNES, British-Steel ...) and rotor-stator contact, in particular in jet engines (ONERA, Safran Aircraft Engines).
The current work focuses on the initiation of phenomena (source mechanisms) but also on their evolution with use (solicitation, environment ...) until now little considered in research work. This ambition is reinforced within the laboratory by synergies from the viewpoint of materials (PoEME group), their behavior (COREFoU group) and multi-scale and heterogeneous modeling (CoNEx and GEOM groups).