Stability analysis of the helicopter supercritical tail drive shaft system with rub-impact and ballistic impact

Ballistic impact damage can cause dynamic instability of the supercritical tail drive shaft system, posing a threat to the helicopter’s safe flight. However, the effect mechanisms of ballistic impact parameters on the stability of the supercritical tail drive shaft system are unknown. Therefore, the stability characteristic equation of the supercritical tail drive shaft system with rub-impact and ballistic impact is established in this paper, which is verified by the dynamic equation through experimental verification, and then the effect laws of the rub-impact and the ballistic impact parameters on the system stability are evaluated. The research work in this paper conducts stability analysis for the first time by comprehensively considering mass loss, center of mass displacement, stiffness decrease, stiffness asymmetry, and rub-impact. Rub-impacts ensure the stable flight capability of the supercritical tail drive shaft system with hole or scratch damage, but the system becomes unstable after crack damage. The reasonable selection of rub-impact parameters is beneficial for improving the system stability, which provides a potential technical approach for the system stability control. This paper can provide new insights into the stability analysis of rotor systems at the theoretical level and assist helicopters in achieving high-reliability operation at the technical application level.