Predicting Material Properties in Tribological Contacts Based on Continuum Dislocation Dynamics

  • Kübler-Tesch, Constantin (KIT Karlsruhe / HKA Karlsruhe)
  • Schulz, Katrin (KIT Karlsruhe / HKA)

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Tribological systems require a delicate balance between high surface resistance to wear and corrosion coupled with the ductility of the bulk material. Recent studies indicate that coatings containing hard par- ticle inclusions can lead to a significant improvement of the material behaviour in tribological systems, as shown in. The particles might induce significant strengthening effect originating from the hindering of dislocation movement. To investigate these mechanisms, the understanding of the kinematics of dislocations evolution around the particles is key for material design. This contribution presents an enhanced dislocation-based crystal plasticity framework based on continuum dislocation dynamics (CDD). In this model, the evolution of dislocation densities is modeled with CDD yielding the plastic slip evolution based on the Orowan’s equation. The framework has been extended to contact problems by considering dislocation dynamics at free surfaces and combined with a formulation for incorporating tribological loading. We apply the model to simplified coating systems with hard particles implemented into a single crystalline matrix material resembling the coating layer. We apply boundary conditions that restrict the dislocation motion at the particle interfaces in order to investigate the dislocation evolution in the vicinity of the matrix-particle interface. The results show that the model captures the accumulation of dislocations at the interface as well as the resulting internal stress fields. We furthermore analyze the impact of particle size and shape on the hardening behavior. Finally, the results are discussed with respect to the mechanical response of coated systems under tribological loading. The extensions of the model are discussed for a better understanding of the underlying physical mechanisms at internal interfaces for the design of tribological systems.