Influence of friction on gear dynamics

Sliding friction between meshing teeth can be a very important of noise and vibrationexcitation source in geared systems. This study presents a single degree of freedom torsionalmodel for a FZG type C single gear pair. Starting from a base dynamic model with timevarying mesh stiffness as the only internal excitation, the influence of additional effects isgradually considered, namely, constant friction coefficients and time varying output torques.In particular, sliding friction is modeled as external and internal linear time varyingexcitation. On the other hand, time varying output torques are also considered as alternative ofconstant driven torque.The gears rotational vibrations are calculated by Runge-Kutta method for differentcombinations of rational speeds, input torques and friction coefficients. The results indicatethat dynamic transmission errors calculated from modeling the friction force as external andinternal excitation are quite different, especially when contact point moves ahead of pitchpoint. However the influence of time variations on output torque is very reduced