The present paper proposes to analyze relations between the behavior of two bodies in contact (local stress and vibration modes) and the rheology of third-body particles. Experiments are performed on a system composed of a polycarbonate disk in contact with a steel cylinder, where birefringent property of polycarbonate allows us to observe shear-stress isovalues. Multiscale numerical simulations involve the coupling between fi-nite elements and discrete elements to model simultaneously nonhomogeneous third-body flows within a confined contact and dynamical behavior of the bodies in contact. Compar-isons between experiments and simulations are performed on the dynamic response of the system, the stress distribution, as well as the evolution of third-body particles within the contact. Such comparisons exhibit not only qualitative results but also quantitative ones and suggest a new approach to study in deeper third-body rheology.

Abstract. When two continuous bodies are in contact and subjected to relative motion, both particle detachment and dynamic instabilities naturally occur. To properly model such interacting phenomena, it is required to take account for the discontinuity of the interfacial layer (usually modeled with Discrete Element Model) as well as the continuity of the bodies in contact (usually modeled with Finite Element Model).For that, the present paper aims at validating experimentally the coupled FEM-DEM method. The experimental set-up aims at modeling the frictional behavior between a holed disk, tied on its exterior side and made of transparent polymer with birefringence property, and an inner rotating cylinder, made of steel. This last is statically enlarged to reach the wanted contact pressure and then animated with constant angular velocity. The birefringence property of the disk is used to dynamically visualize the evolution of stresses in the disk at both contact scale and body scale.Based on the same principle with the same boundary conditions, the numerical model coupled the modeling of a deformable disk, a pseudo-rigid cylinder and wear particles by a combination of a finite element method and a discrete element method. Parametrical study has been numerically made to study the influence of particle morphology on stress evolution in the disk.A good agreement is showed between the numerical results obtained with particles artificially introduced in the contact and the experimental results obtained with wear particles naturally produced in the contact.