Research On Friction And Wear Characteristic Of Aviation Involute Spline Couplings Under Axis Deviation And Bending Stress

Involute spline couplings is made of male spline and female spline. Compared to other key joint, involute spline couplings has so many advantages such as automatically centering, stable contact characters, long fatigue life and the capacity of bearing is marvelous. It is widely used in aviation industry while it stands poor working conditions; vibration results in tiny displacement when it delivers load which is easily get fretting damage. Above all reasons, it is high time that the research on fretting damage of aviation involute spline couplings is extremely important.Firstly, through mixed programming of VB.NET and CATIA, the design and modeling software of spline coupling was achieved, and assembly model of spline coupling was parameterized.The contact property of aviation involute spline couplings model was developed to analyze changes of contact stress and relative slip distributions, in which axis deviation was considered. Based on finite element method, the nonlinear friction contact property of spline couplings was analyzed, which is focused on the fretting damage of each tooth. At the same time, the concept of friction power is taken into account and analyze the changes of spline couplings under different moment. The results show that axis deviation significantly increases the value of contact stress and relative slip in the spline couplings, which gives rise to uneven wear damage. With the increasing deviation, the value of contact stress and relative slip raise accordingly, while the increment is negligible. In pace with increasing load of moment, the value of friction power raises accordingly, but the amplitude is comparatively invariable.Secondly, fretting damage of spline couplings was calculated by finite element method when main parameters were under consideration, such as friction coefficient, spline pore diameter, contact length, numbers of tooth and module. The results show that increasing friction coefficient appropriately decreases uneven distribution of relative slip. Spline pore diameter could not be too large and contact length should be no less than half of the total length when designing involute spline couplings. The more numbers of tooth, the more fretting damage of the spline couplings. The value of contact stress declines rapidly when module is on the increase.Then, fretting damage of spline couplings under deflection was analyzed. The boundary condition of spline couplings was defined again to make it hinged above both ends. It was as same as the real working condition module. Aviation involute spline couplings model was developed to analyze changes of contact stress and relative slip distributions when it is under both bending stress and torque.The results show that it is easily getting fretting damage when bending stress and torque affects. The contact stress and relative slip distribution chart of each tooth in spline couplings were obtained when deflection was taken into account.Finally, due to fretting damage was basic characters of the spline couplings, gradient material was applied to the spline in order to polish its surface intensity and fatigue life. For the sake of testing the effect of gradient material, electrical servo shaft testing machine was used to contrasting. The results show that new plated part enhances the intensity and the capacity of abrasion resistant. When quantitative analysis is applied to the result, fretting damage spot of the tooth face could cut down 71.4%, compared to normal spline couplings. Meanwhile, when the spline couplings were under axis deviation, reloading the testing machine to measure the value of damage. The experiment shows that fretting damage of each tooth is not the same, which validate the theoretical analysis.