Simulation of Fracture Initiation in Sliding Contact of Brittle Coatings on Elastoplastic Substrates.

In metal forming, failure of coated tools often indicate problems related to sliding contact, fretting, and substrate plasticity. To date, failure prediction of tools subjected to sliding and fretting contact has been largely based on elastic analysis if not empirical. As an effort to understand the issue and specifically, to investigate the role of plasticity, a finite element-based analysis of plane strain contact of brittle coating is performed. The problem consists of cyclically loading a rounded-edge punch in normal and tangential directions to a coated substrate. The results are presented for the maximum principal stress in the coating indicative of brittle failure and the evolution of plastic deformation in the substrate. These quantities are analyzed as functions of substrate’s plasticity parameters, coating’s elastic modulus, friction, and loading parameters. A combined isotropic-kinematic hardening plasticity law is considered. The prediction of the tool’s service life based on the above failure conditions is also discussed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]