Influences of spline coupling on stability of rotor-bearing system

Meshing force model of loosely meshed spline coupling considered the critical disjointed condition is derived, dynamic equation of rotor-spline coupling-bearing system with the action of coupling mesh and nonlinear oil forces is established based on finite element analysis. The influence of spline coupling on stability of rotor-bearing system is simulated by the numerical integral method. Research results show that the influence of lateral stiffness of spline coupling on system threshold speed of oil whipping instability is weak, however, the influence of angular stiffness is larger. For loosely meshed spline coupling, the angular stiffness is not considered, system threshold speed of instability obtained by linearized mesh stiffness of coupling is larger than the one obtainted by mesh force. Therefore, in real engineering project, meshing stiffness, instead of meshing force, used to model coupling will conceal the real threshold speed of instability of rotor-bearing system, and this simplification is unsafe for operation of rotor system. Research results can provide theoretical evidence for obtaining the real threshold speed of instability of rotor-spline coupling-bearing system, and this approach can provides guidance for other kinds of couplings.