Abstract: Spline couplings are widely used in the aviation field. The splines often fail to reach their expected life under complex working conditions, and the angular misalignment between spline shafts has a greater impact on the service life of the couplings. An efficient three-dimensional simulation model is established based on the finite element method to analyze the load distribution of spline teeth when the internal spline deviates 0.3° from the external spline. The wear depth of each node in the contact area is calculated based on the Archard wear model, and the UMESHMOTION subroutine and Arbitrary Lagrangian-Eulerian technique are adopted to remesh the calculation domain after each cycle. The critical plane methods, Brown-Miller and Smith-Watson-Topper, are used to predict fatigue life based on the analysis of stress states on the tooth surface and those near the tooth root. Expressions are fitted involving the cyclic life, maximum wear depth and wear coefficient. An experimental study is conducted to verify the model. The conclusions may provide guidance for the design and verification of the spline coupling. The results show that the stress concentrations are gradually released along with the surface evolution, which can elongate the residual life of splines. The splines fail to work due to wear when a large wear coefficient is produced and due to fatigue crack initiation when the wear coefficient is relatively small.

Key words: aviation spline coupling, angular misalignment, fretting wear, fatigue analysis, development of finite element method