A Simple Semi-Analytic Contact Mechanical Model for Tangential and Torsional Fretting Wear of Axisymmetric Contacts

Fretting wear of axisymmetric contacts is considered within the framework of the Hertz–Mindlin approximation and the Archard law for the linear wear. If the characteristic time scale for the wear is much larger than the duration of a single fretting oscillation, the profile change due to wear during one fretting cycle can be neglected for the contact problem as a zero-order approximation. This allows to give an exact contact solution during each fretting cycle, depending on the current worn profile, and thus for the explicit statement of an ordinary integro-differential equation system for the time-evolution of the fretting profile, which can be easily solved numerically. The proposed method gives the same results as a known, contact mechanically more rigorous simulation procedure that also operates within the framework of the Hertz–Mindlin approximation, but works significantly faster than the latter one. Tangential and torsional fretting wear are considered in detail. A comparison of the numerical prediction for the evolution of the worn profile in partial slip torsional fretting of a rubber ball on abrasive paper shows good agreement with experimental results from the literature.

Study on tribo-chemical and fatigue behavior of 316L austenitic stainless steel in torsional fretting fatigue

Fretting fatigue is a complex tribological phenomenon that can cause premature failure of connected components. Combining with the effects of tribological and fatigue, the components have premature fracture, which ultimately leads to disastrous consequences. In this work, the fretting fatigue tests of 316L austenitic stainless steel have been carried out with same normal load and varied torsional torques. The results indicate that the fretting fatigue life significantly depends on the torque amplitude, wear degree of the fretting damage zone, hysteresis loops and energy dissipation. A physical model for fretting crack initiation and propagation is created to explain the failure process of torsional fretting fatigue. The results from X-ray photoelectron spectroscopy analysis show that the extent of oxidation in the fretting damage zone is affected by the amplitude of relative displacement. The tribo-chemical reaction in the slip regime is more activated than that in partial slip regime. It can lead to more severe wear in the slip regime. The wear debris of the fretting damage zone is composed of metallic Fe, Fe2+ and Fe3+.