Analysis on bistable response of a disk-rod-fastening rotor

In view of the fault of bistable response appeared in the disk-rod-fastening rotor,the peculiar structure of this kind of rotor was taken into account.By considering the influence of contact effect of discontinuous interfaces on the rotor stiffness,the tie-rod and the contact surface between the wheel disks were equated to a bending resistance spring with nonlinear stiffness.Then the equation of motion of the disk-rod-fastening rotor was established according to this simplification.The vibration characteristics of rotor were calculated by the harmonic balance method with introduction of the predict-correct and homotopy arithmetics.The bistable response behaviors recurred in this simplified model were much closer to the measured results in flight.The study shows that the nonlinear factor of stiffness,resulted from the contact effect of discontinuous interfaces,was a main reason leading to the appearance of bistable response in the disk-rod-fastening rotor.The bistable region can be reduced by the way of adjusting the system parameters to some appropriate values.