The scuffing load capacity of involute spur gear systems based on dynamic loads and transient thermal elastohydrodynamic lubrication

• Dynamic loads based on meshing stiffness were calculated by numerical method.
• Temperature rise model of the contact region in time domain was proposed.
• Transient thermal elastohydrodynamic lubrication (TEHL) model considering dynamic loads were calculated.
• Flash temperature and film thickness were closed to Blok and Dowson equation.
• The TEHL method is applied to check if the scuffing load capacity is effective.

A method for predicting scuffing failure in spur gear pairs by means of a transient thermal solver is proposed in this paper. The quasi-static and non-linear dynamic models of spur gear systems are established based on time-varying stiffness. The dynamic loads in meshing cycle are calculated. The transient effect is most pronounced at exchange point between single and double teeth region as well as greatly influenced by damping ratio. The temperature rise formula is proposed based on transient heat flux. The transient thermal elastohydrodynamic lubrication (TEHL) model which takes the dynamic loads into account is proposed and the distributions of pressure, film thickness and temperature are obtained. The flash temperature and minimum film thickness in meshing cycle are obtained and applied to check the scuffing load capacity. A comprehensively comparison between TEHL theory and Blok theory is implemented and the results turn out that the TEHL theory is more close to the actual conditions in theory. The distributions of flash temperature and minimum thickness with TEHL method are consistent with that of Blok flash temperature and thickness of Dowson, respectively. The scuffing load capacity is greatly influenced by dynamic effect.