Incipient Sliding Analysis Between Two Contacting Bodies. Critical Analysis of Friction Law

Thami Zeghloul (1) , Marie-Christine Baietto (2) , Bernard Villechaise (1)

1 LMS - Laboratoire de mécanique des solides
2 LMSt - Laboratoire de Mécanique des Structures

Two non-conforming bodies are brought into contact. They touch over a plane surface of extent size compared with the dimensions of the solids. Then they are subjected to a tangential force until gross sliding is observed at the contact interface. Under certain circumstances, this phenomemom is preceeded by local slidings over part of the contact area, named as “sliding waves”. They are similar to the Schallamach waves. Relations between these instabilities and the stick limit and the friction conditions on one hand and with the body compliance on the other hand must be investigated as they generate vibratory phenomena like for instance judder. Progri et al. [1] have identified the experimental conditions for reproducing these phenomena. A two-body contact is established between a rectangular polyurethane slab (L = 80mm, 1 = 10mm, h = 40mm, Young modulus E = 7 MPa, Poisson's ratio v=0.48) and an araldite flat, considered as rigid comparatively. Phenomenological description of these phenomena was performed. Mouwakeh et al [2] performed a quantitative analysis and show that the energy dissipated during sliding was comparable with the energy associated with the propagation of a shearing mode interface crack. Numerical simulations based on variational formulations were proposed by numerous authors, and more particularly by Raous [3]. The friction law used is the Coulomb's law. Sliding waves are observed experimentally at one edge of the contact area, sweep through it first partially, then entirely and lead finally to gross sliding. Correct modelling of all stages of the sliding evolution from rest up to gross sliding is still not performed: a central slip zone is predicted, based on the assumption of a friction coefficient equal to the ratio of the tangential load corresponding to the gross sliding over the normal load. This study deals with these differences. Thus: - modelling of interface behaviours based on the Coulomb's law were listed. The numerical model is based on a combination of the finite element technique, the interfacial crack theory and the unilateral contact analysis with friction. Geometrical dimensions of the slab and the friction coefficient value have a great influence on the way the sliding stages progress.- Tests were realised to give an accurate phenomenological description of the sliding waves. The influence of both the geometrical dimensions of the slab and the friction coefficient value have been verified. Further both load and displacement variations when the sliding waves sweep through the contact area, partially or totally, were performed. Particularly, informations on the influence of the loading speed on sliding were obtained.For the configuration studied, incipient slidings are highly dependent on the parameters mentionned above. These results can't be extrapolated directly to industrial configurations due to the difference in material, a very compliant one in tests, rigid ones in industry. But this device is of a great help for local frictional behaviour analysis. Comparisons between experimental and theoretical results and the behaviours noted from the parametric study lead to the conclusion that a parameter adjustement will allow to model sliding stages with a Coulomb law type.

Domaines: Sciences de l'ingénieur [physics]

Thami Zeghloul, Marie-Christine Baietto, Bernard Villechaise. Incipient Sliding Analysis Between Two Contacting Bodies. Critical Analysis of Friction Law. Science direct, 1994, 27 (C), pp.549-557. ⟨10.1016/S0167-8922(08)70340-7⟩. ⟨hal-01951922⟩