Dynamic Characteristics Analysis of High-Speed Fixed-Axis Gear Pair with Spalling Fault for a Wind Turbine Gearbox Considering Friction and Flash Temperature

As one of the main forms of gear failure, tooth spalling makes the pit occur on the tooth surface and causes the gear not to mesh normally. Friction, an important factor in gear transmission, not only exacerbates the system vibration but also leads to the flash temperature on the tooth surface, and then the flash temperature reduces the gear stiffness. Hence, this paper reveals the relationship between gear spalling and nonlinear dynamics for a wind turbine gearbox considering friction and flash temperature. The friction force and flash temperature are calculated using Coulomb’s law and Blok’s flash temperature theory, respectively. The time-varying flash temperature stiffness and meshing stiffness of gears with spalling are separately obtained based on Hertz’s theory and potential energy method. The torsional dynamic model of the gearbox with high-speed driving gear spalling is established to study the influences of friction, flash temperature, and spalling on the dynamic behaviors, and the frequency spectrums of simulation and experiment of gear spalling are compared. The results indicate that the gear spalling and flash temperature make the comprehensive time-varying meshing stiffness decrease, and then affect the dynamic characteristics of the system in various friction states, especially dry friction. The friction and spalling change the chaotic motion interval in the high-frequency region, but the flash temperature affects the low-frequency region greatly and increases the quasi-periodic interval. The research provides significant guidance for monitoring the spalling fault of multi-stage gear transmission systems.