Coupling system dynamics and contact behaviour by numerical modelling at different scales

When dealing with mechanical systems including contact interfaces, two different mechanics at two different time and length scales have to be accounted for: the contact mechanics and the structural mechanics. The mechanics of the contact and the mechanics of structure are coupled by friction (forces and moments), local body deformations and wear (geometrical coupling). In the past, dynamic and tribological problems were treated separately and the analysis was focused either on the mechanism scales or on the contact scales, as a function of the problem. The analysis of the dynamic response of the mechanical system accounted for the contact interfaces thought global coefficients (global contact stiffness, damping, energy loss factor, etc.); vice versa, the analysis of the local behaviour at the contact interface accounted for the system dynamics imposing global boundary conditions on the contact model (pressure distribution, relative velocities, etc.). During last decades mechanical system design led to a power increase and to a drastic optimization, increasing as well the number of contact interfaces between deformable bodies. Thus, the need for coupling dynamic and tribological analyses arises for solving and understanding either wear phenomena or dynamic response of a mechanical system. On this sense, experimental tools showed their limits on the estimation and prediction of friction and wear phenomena. This paper proposes a first step toward a more general approach aimed to couple the dynamic analysis of the mechanism with the local tribological analysis at the contact, by the coupling of two different numerical models dealing with the two different scales. Two applications are then mentioned: the analysis of "false Brinelling" wear and the understanding of brake squeal instability. Copyright © 2010 by ASME.