Nonlinear Vibration Characteristics of the Involute Spline Coupling in Aeroengine with the Parallel Misalignment

In order to control the vibration of the involute spline coupling in aeroengine well and reduce the fretting wear, a bending–torsion coupling nonlinear vibration model of the involute spline coupling with the misalignment was proposed, and a dynamic meshing stiffness function with multiteeth engagement was established. Then, the influence of different misalignment, wear, and rotation speeds with different misalignment on the nonlinear vibration characteristics of the involute aviation spline coupling was explored. The result shows that with an increase of the parallel misalignment, the system experienced the state of a single period, a quasiperiod, multiperiod, and chaos but finally only alternated between the quasiperiod and the chaos state. The uneven wear of each tooth of the spline displayed a significant influence on the vibration of the spline coupling, and the influence of the uniform wear was smaller under given conditions here. Furthermore, with an increase of the speed, the larger the misalignment was, the more times the system entered or left the chaos state were. The model proposed here is found to be closer to the actual working conditions, and the analysis results can provide more accurate external load conditions for the prediction of the fretting damage of the spline coupling in aeroengine.

Nonlinear dynamic load analysis of aviation spline coupling with mass eccentricity and misalignment

Most of the time, mass eccentricity, and misalignment exist at the same time with aviation spline coupling working. Therefore, in this paper, the function of dynamic meshing force between multi-teeth and a non-linear dynamic model of involute spline coupling system in aero-engine with mass eccentricity and misalignment were presented. And then, the non-linear dynamic meshing force of spline coupling in aero-engine on different misalignment and mass eccentricity was investigated. The result shows that when the mass eccentricity and the misalignment are both small, the aviation involute spline coupling can run steady. And with the increase of mass eccentricity or misalignment, the dynamic load coefficient of the aviation involute spline coupling gradually increase. At the same time, as the mass eccentricity or misalignment increases, some teeth suffer more load, some teeth suffer less load, and some teeth are out of engagement so that they do not suffer any load. The running state of spline coupling becomes more and more unstable.

Involute spline couplings in aero-engine: Predicting nonlinear dynamic response with mass eccentricity

This work presents a nonlinear dynamic model considering the multi-tooth meshing behaviour and mass eccentricity of an involute spline coupling to tackle the serious problem of involute spline failure, in aviation power transmission systems. The dynamic meshing force is calculated for the same. Based on this, the influence of different mass eccentricities on the nonlinear dynamic response of the spline coupling was investigated in aero-engines. The results show that when the mass eccentricity is small, its impact on the system is insignificant. When the eccentricity reaches a certain value, the quasi-periodic and chaotic state appears alternately. Meanwhile, it can be concluded that the acceleration-frequency spectrum during the multi-periodic phase is an approximation of the working frequency with the accuracy affected by multiple teeth engagements. This was validated by the vibration experiments of the involute spline coupling. The proposed model, which considers the multi-tooth meshing behaviour and the mass eccentricity provides a reference model for the dynamic analysis of similar structures. The nonlinear dynamic response results attained lay a good theoretical foundation for fretting damage analysis and precise designs for involute spline couplings.

Experimental investigation and prediction method of fretting wear in rack-plane spline couplings

To investigate the fretting wear of involute spline couplings in aerospace, rack-plane spline couplings rather than the conventional involute spline couplings in aerospace were used to conduct tribological experiments, and it was assumed that the rack-plane spline couplings exhibit consistent contact stress with the real involute spline couplings in aerospace. The relationships among the static friction coefficient, dynamic friction coefficient, and fretting friction coefficient were established via tribological experiments, as well as the fretting-wear mechanism of the rack-plane spline couplings was examined. A fretting-wear estimation model based on the fretting-wear mechanism was developed. By applying the modified Archard equation and Arbitrary Lagrangian–Eulerian adaptive, mesh smoothing algorithm of Abacus was used. According to our experimental results, the fretting wear of the rack-plane spline couplings consisted primarily of abrasive wear, oxidative wear, and adhesive wear. For both, lubrication and non-lubrication settings, the fretting friction coefficient of 18CrNi4A steel (0.27) fluctuated between 0.12 (dynamic friction coefficient) and 0.35 (static friction coefficient). The fretting-wear results estimated via numerical prediction were consistent with the experimental results. When sm (vibration amplitude) was 20, 35, and 50 µm, the most difference in the fretting wear between the experimental results and numerical estimation was 0.001, 0.0007, and 0.001 mm, respectively. Therefore, the proposed model provides a method for accurate estimation of the fretting-wear. Additionally, the model contributes to the precise design of involute spline couplings in aerospace.