In order to study the influence of the flash temperature on the crack fault characteristic of a wind turbine gearbox

the temperature and profile deformation of the tooth are calculated using the Blok flash temperature theory and thermal deformation formula

respectively

and the tooth stiffness considering the flash temperature is obtained using the Hertz contact theory. For the gearbox with crack fault occurred on the tooth root of the high-speed gear

the torsional dynamic model is established considering flash temperature

damping

meshing stiffness

transmission error and backlash. The variation laws of the vibration characteristics with flash temperature are investigated under different crack conditions through time domain

frequency spectrum

phase diagram and Poincaré section

and the numerical results in the time-frequency domain are compared with those of the test without considering the flash temperature. The results show that the flash temperature makes the impact amplitude from the crack in the time domain increase

the fault side frequency be more complex

the phase diagram expand and the number of discrete points in Poincaré section increase

and the changes are more obvious with increasing the crack length. The research provides the basis for diagnosing and monitoring the gear crack fault state.