A ballistic impact identification method for the helicopter tail drive shaft system based on vibration response analysis

The ballistic impact identification method for the helicopter Tail Drive Shaft System (TDSS) isn’t yet comprehensive, which affects helicopter flight safety. This paper proposes a ballistic impact identification method for the TDSS based on vibration response analysis. Based on the Johnson-Cook constitutive model and failure criteria, the ballistic impact finite element simulation model is established, which is verified by the ballistic impact experiment of the Tail Drive Shaft (TDS). Considering the ballistic impact excitation force, the dynamic model of the TDSS with ballistic impact is established, which is verified by finite element commercial software. If a bullet hits the TDS, the bending vibration displacement increases sharply at a certain moment and then significantly increases but remains stable. Meanwhile, the critical speed component appears in the frequency-domain response of bending vibration, and then the speed component significantly increases but remains stable. What’s more, the axis trajectory exhibits a sudden, large-scale, and irregular whirling motion at a certain moment, followed by a significant increase but remains stable. Furthermore, if the axial vibration response is small, the bullet core shooting should be considered vertically or at a small incident angle, otherwise, it should be considered at a large incident angle.