Fault mechanism of spur gears with crack damage of pitch circle
                                                                        WENG Wuyan1,2, WU Yuren2
(1.School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350116, China;2.College of Engineering, Central University, Taoyuan 32001, China)

Abstract: Aiming at the problem of gear pitch circles are heavily affected by the alternating loads, which could easily lead to fatigue cracks，a coupling of 12degreeoffreedom gearrotorbearing bendingtorsion coupling was established by considering the coupling relationship between gear, rotor and bearing. The kinematic model and the effects of the pitch circle crack on the gear transmission system were reflected by the change of the integrated timevarying mesh stiffness. The Rungekutta numerical solution was applied to formulate the differential equation of motion of spur gear transmission, and the dynamic response of the system under the circular crack with pitching was obtained, and which were applied to investigate the dimensionless parameter indicators in the dynamic response of the system. The results indicate that the corresponding damage signal appears in the timefrequency domain of the gear system when the crack occurs in the pitch circle. Meanwhile, the kurtosis pitch, margin factor, peak factor and pulse factor of the vibration signal sequence have obvious changes, and as the crack deepens, the kurtosis pitch of the vibration signal sequence also increases accordingly. This study can provide theoretical basis for the evolutionary mechanism of the crack damage in the gear pitch circles and the fault diagnosis of the gear transmission.

Key words: spur gear; crack; timefrequency characteristic; crack damage