Analysis of factors affecting the wear failure of an aeroengine spline pair and evolution mechanism of the tribolayer

Abstract

Involute spline shafts are widely used in aerospace applications. Splines often undergo severe failure due to wear under complex operating conditions, and their life expectancy often falls short of expectations. We simulated and characterized an aero-engine involute spline that failed after 1000 h of actual flight in an aero-engine. The results showed that the local stress concentration area analyzed in the simulation matched the actual area that underwent severe wear in the spline pair. The microstructure and misalignment of the involute spline subsets affected the wear and loss of efficiency. The fretting tribolayer was analyzed using ion beam in situ cutting and high-resolution transmission characterization techniques. High-density dislocation lamellar structures and oxide nanoparticles formed by martensite that underwent strong plastic deformation in the tribolayer were present, and microcracks were found in both the nanosized lamellar structure and oxide particles. Based on combining the above characterization results, the microscopic mechanism and a model of drive shaft failure were proposed. Cracks that formed inside brittle oxides and the nano-scale lamellae were the main causes of the eventual failure due to fretting wear. The above mechanism provides a theoretical basis for deepening the understanding of the process and essential reasons for spline pair failure as well as improving the production process and increasing the service life of spline pairs.