Abstract: In order to examine the influence of the tooth contact temperature in the meshing surface on the dynamics in the gear system, the flash temperature in tooth surface of driving gear and driven gear is calculated based on Block’s flash temperature theory. The mathematical expression of the tooth contact temperature changed with time in the tooth surface is derived and the tooth profile deformation caused by the change of contact temperature in the tooth surface is computed. The expression of the mesh stiffness which is modified by the contact temperature in the tooth surface is derived based on Hertz contact theory. A nonlinear dynamic model of a single-stage spur gear system is established when the nonlinear factors such as the tooth contact temperature, the time-varying stiffness, the tooth surface friction, the backlash and the transmission error are considered. The dynamics of the system are analyzed. The influence of coefficient of friction and load on the flash temperature of the tooth surface is analyzed, too. The calculated results show that the maximum of the flash temperature in the tooth surface appears when the gear meshes at teeth top and teeth root and it reaches to zero near the pitch point. It indicates that the calculated method of the flash temperature of the gear tooth surface is correct and it can reflect the rules for the change of gear meshing temperature and sliding of the gear tooth surface. The tooth contact temperature has an obvious effect on the dynamics of the gear system according to comparison the bifurcation diagram of considering the tooth contact temperature and the one neglecting the tooth contact temperature.

Key words: gear, modelling, nonlinear dynamics, tooth contact temperature