Plasticity in fretting contact

The fretting problem of a cyclically loaded cylinder on a flat elastic-plas tic surface is analyzed under the assumption of plane strain. Severe fretti ng conditions are modeled by applying a constant normal load and a cyclic t angential load to the cylinder and describing the contact behavior using a Coulomb friction law. Detailed numerical results are presented for the evol ution of plastic strains in the substrate as a function of loading and fric tion coefficient. Shakedown maps and cyclic plastic strain behavior maps ar e created to describe the relative contribution of cyclic plasticity, ratch eting and shakedown as a function of loading. Cyclic plastic strain amplitu des are presented as a function of tangential load amplitude for various le vels of normal pressure and friction using extensive finite element computa tions. Several plasticity models are considered: elastic/perfectly-plastic, isotropic strain hardening and kinematic strain hardening. The results ind icate that, while the plastic strain amplitudes decrease with increased str ain hardening, the qualitative behavior is insensitive to the choice of pla sticity model. The results are compared with corresponding fully elastic an alyses to highlight the role of plasticity during contact deformation and t o evaluate the implications of using fully elastic analyses to predict crac k nucleation. (C) 2000 Elsevier Science Ltd. All rights reserved.