Vectorial feature and evolution of run-in attractors for the AgCu-MoS₂/AgCu10 tribo-pair

Abstract Run-in process is a very critical stage before the solid self-lubricating friction pair reaches a steady state. For the identification and prediction of run-in states for AgCu-MoS 2 /AgCu10 tribo-pair, it is important to understand its evolution law. The run-in tests were carried out under different conditions with a pin-on-disc tribometer, and its friction coefficient signal was collected. Reconstructing phase trajectories using phase space reconstruction and principal component analysis is presented. As an alternative to traditional parameters, we propose vectorial feature parameters with minimum cosine similarity ( S_cos_min ) and maximum distance between adjacent phase points ( Dist_max ). S_cos_min and Dist_max identify changes in state and characteristics of the run-in attractor, as well as describe its evolution. The evolution of transfer film morphology on the counter surface demonstrated that the vectorial feature parameters could be used as run-in criteria.