A new dynamic model of a cylindrical gear pair with localized spalling defects

Abstract

Accurate assessment and modeling of the effects of tooth defects on the vibration response of gear systems is beneficial for the early detection and diagnosis of gear faults and failures. This paper presents a new dynamic model of a cylindrical gear pair with localized tooth spalling defects. Depending on the depth and extent of a spall, the resulting contribution of the spall to the gear dynamics can be classified in terms of mesh stiffness reduction and displacement excitation. The main improvement of the proposed model, relative to previous similar models which assume a linear line contact between mating tooth pairs, is that modification coefficients are introduced to account for the effects of nonlinear elliptical tooth surface contact pattern on the influencing mechanisms of the spalls on the gear dynamics. It was found that the modification coefficients are dependent on the transmitted load, the dimensions of the spall, and the amount of tooth crowning. Experimental vibration responses of several 1:1 ratio spur gear pair sets with different dimensions of spalling defects working under various load and speed conditions were measured to compare with the simulated results based on the proposed model and previous similar models in terms of the time-history acceleration, power spectrum and some statistical indicators. The results validate the superiority of the proposed model against previous similar models.