Tooth Friction in Models of Gears

The aim of this report is research on dynamics in gears on the basis of models with regard to tooth friction, considered as Coulomb’s dry friction, as well as an evaluation of its influence on dynamic behaviour of gears. The models of isolated and non-isolated gear transmissions are under our consideration. The non-isolated one includes additionally the input and output parameters of shafts. The mesh description includes tooth stiffness varying on the line of action and the function of the mesh parameters that depends on the mesh phase, clearances, pitch and profile deviations as well as the mesh displacements. Generally, the form of this function is consistent with the modified Müller’s model (see Müller, 1996). Assuming frictional resistance in the mesh, on the basis of the carried out researches some detailed conclusions considering the applied levels of the equivalent damping and damping distribution of dissipative forces in the gear models are formulated. The influence of friction on the maximal values of dynamic forces appears in the low range of rotational speeds and also in the resonant zones. Introduction of the friction forces into the models gives us more accurate mesh description, and thus additional explanation for the sources of dynamic loads in gears.