Regimes of Contact in Spline Couplings

The contact between the male and female teeth of involute spline couplings connecting misaligned transmission shafts has been studied using an elastostatic contact model with stick-slip friction based on the boundary integral element method. The effect on the distribution of pressure and on the slip path during shaft rotation, of a wide range of design parameters and of applied torque and misalignment has been explored. The predicted behavior is classified according to the regime of friction (cyclic stick-slip or gross slip) and to that of the pressure history (uniform, cyclic, discontinuous, or toppled). The magnitude of the maximum tooth load, the axial skewness of the distribution of pressure and a maximum wear depth parameter are presented in terms of dimensionless design and operating parameters. The effect of tooth crowning is briefly examined. The results show a number of previously unreported features including a cyclic tooth load—which declines to zero for certain conditions—and an effective slip amplitude of around half the rigid-body value. This may affect the interpretation of laboratory fretting tests.