On the numerical modeling of frictional wear phenomena

The evolution of the contact surfaces wear may become particularly importan t in the definition of the frictional behavior, in particular for frictiona l contact problems involving large slips, typically in sheet metal forming and bulk forming operations. Despite this fact. most of the current applica tions reported in the literature are restricted to a standard Coulomb law, using a constant friction coefficient. Such simple models may represent onl y a limited range of tribological situations and it appears to be: necessar y to develop a class of models which incorporate the tate conditions and th eir evolution at the contact surfaces, taking into account the influence of complex phenomena such as wear, lubrication and chemical reactions, among others, see Oden and Martins [1], In this paper a simple numerical model for the simulation of frictional wea r behavior, within a fully nonlinear kinematic setting, including large sli p and finite deformation, is presented. The model relies on the introductio n of an internal variable related to the state conditions at the contact su rface. Here, two possible definitions of this internal variable have been c onsidered. The fully nonlinear frictional contact formulation, entirely der ived first on a continuum setting by Laursen and Simo [2-6], has been exten ded here to accommodate the characterization of the wear frictional behavio r. Within the computational aspects, two families of robust time stepping algo rithms, arising from an operator split of the constrained frictional evolut ion equations, are discussed. Finally, following current approaches, see Lassen [9], Lassen and Bay [10], OH rn et al. [II], de Souza et al. [12]. Stromberg et al. [1.7] and Stromb erg [14], a long-term tools wear prediction is given by introducing an a pr iori wear estimate derived from Archard's law, Archard [15]. The numerical model has been implemented into an enhanced version of the co mputational finite element program FEAP. Numerical examples show the suitab ility of the proposed model to capture the essential features of the fricti onal behavior at the contact interfaces and to provide a prediction of tool wear in forming operations. (C) 1999 Elsevier Science S.A. All rights rese rved.