Plasticity in fretting contact

The fretting problem of a cyclically loaded cylinder on a flat elastic-plastic surface is analyzed under the assumption of plane strain. Severe fretting conditions are modeled by applying a constant normal load and a cyclic tangential load to the cylinder and describing the contact behavior using a Coulomb friction law. Detailed numerical results are presented for the evolution of plastic strains in the substrate as a function of loading and friction coefficient. Shakedown maps and cyclic plastic strain behavior maps are created to describe the relative contribution of cyclic plasticity, ratcheting and shakedown as a function of loading. Cyclic plastic strain amplitudes are presented as a function of tangential load amplitude for various levels of normal pressure and friction using extensive finite element computations. Several plasticity models are considered: elastic/perfectly-plastic, isotropic strain hardening and kinematic strain hardening. The results indicate that, while the plastic strain amplitudes decrease with increased strain hardening, the qualitative behavior is insensitive to the choice of plasticity model. The results are compared with corresponding fully elastic analyses to highlight the role of plasticity during contact deformation and to evaluate the implications of using fully elastic analyses to predict crack nucleation. (C) 2000 Elsevier Science Ltd. All rights reserved.