BTAP dynamic model establishment and influence analysis of marine two-stage herringbone gear transmission system considering cracks

Abstract

To reveal the influence of cracks on the vibration characteristics of marine two-stage herringbone gear transmission system (TSHBGTS), a 48 degree of freedom bending-torsional-axial-pendular (BTAP) dynamic model of the system was established, which took into account the influence factors such as error, time-varying meshing stiffness (TVMS), torsional stiffness, support stiffness, tooth surface friction, and undercut. In the model, the TVMS of each gear pair in the Two-stage herringbone gear system with cracks was calculated by using the potential energy method, and the TVMS variation rule under different lengths, depths, and angle parameters of cracks was analyzed. The Runge-Kutta numerical integration method was used to solve the problem. The influence of different crack degrees on the vibration of each position of the TSHBGTS was analyzed. The influence of different crack degrees on the vibration response of was tested through tests. The difference in mechanical vibration between the normal gear and cracked gear was analyzed by using the frequency domain diagram and time domain diagram, and the influence mechanism of cracks on vibration characteristics was revealed. The results show that when the gear cracks, the TVMS of the gear decreases, and with the increase of the crack depth and length, the TVMS of the gear pair will gradually decrease. With the increase of crack depth and length, the TVMS of the gear pair is greatly reduced, and there is a periodic impact phenomenon in the time domain response of the system. With the continuous expansion of the crack, the impact phenomenon becomes more and more serious. In the frequency domain response, a modulated sideband centered on the meshing frequency appears. When the crack is generated and the crack degree increases, a small noise frequency is generated near the frequency doubling and increases with the growth of the crack. The correctness of the theoretical analysis model is verified through experiments, and the research results can provide a theoretical basis for the fault diagnosis of the herringbone gear transmission systems with cracks.