Abstract
Meshing force of misaligned spline coupling is derived, dynamic equation of rotor-spline coupling system is established based on finite element analysis, the influence of meshing force on rotor-spline coupling system is simulated by numerical integral method. According to the theoretical analysis, meshing force of spline coupling is related to coupling parameters, misalignment, transmitting torque, static misalignment, dynamic vibration displacement, and so on. The meshing force increases nonlinearly with increasing the spline thickness and static misalignment or decreasing alignment meshing distance (AMD). Stiffness of coupling relates to dynamic vibration displacement, and static misalignment is not a constant. Dynamic behaviors of rotor-spline coupling system reveal the following: 1X-rotating speed is the main response frequency of system when there is no misalignment; while 2X-rotating speed appears when misalignment is present. Moreover, when misalignment increases, vibration of the system gets intricate; shaft orbit departs from origin, and magnitudes of all frequencies increase. Research results can provide important criterions on both optimization design of spline coupling and trouble shooting of rotor systems.
Highlights
The problem of misalignment encountered in rotating machinery is of great concern to designers and maintenance engineers
The results show the predictability of rotor system instability due to internal fiction, which has been experimentally observed, especially for axial splines
(b) The slope coefficient of meshing force curve reflects the stiffness of coupling, during the vibration of system, the stiffness of coupling is not a constant, it relates to dynamic vibration displacement and depends on static misalignment
Summary
The problem of misalignment encountered in rotating machinery is of great concern to designers and maintenance engineers. Because of high-rotating speed (such as pump in rocket) or large transmitting torque (such as output shaft in ship) of rotors connected by spline coupling, the support conditions which get much rigorous would cause misalignment of spline coupling unavoidablely. It has been observed by the author on several occasions that rotating machinery stability conditions can change should the alignment state between the driver and the driven machines changes [4]. In 1994, the report of NASA [13] provides the first opportunity to quantify the angular stiffness and equivalent viscous damping coefficients of an axial-spline coupling used in high-speed turbomachinery with experimental method. To gain a greater insight of the effect of spline coupling on rotor system, the dynamic model of rotor-spline coupling system was presented with finite element analysis, Newmark-beta numerical integration method was employed to analyzing the dynamics of the system
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