Influence of kinematic parameters and tooth geometry on gear tooth root load capacity

Abstract

Spur gear load carrying capacity and mass are primarily dependent of the tooth root stress. Geometric and kinematic parameters of gear teeth pairs produce multiple effects on the tooth root stress: through tooth root critical section location and root fillet radius, tooth profile shape and load leading point location on tooth profile, as well as through tooth stiffness. In the conventional calculation procedure, according to ISO standard, the influence of geometric and kinematic parameters of the gear pair on the tooth root stress is considered through the "contact ratio factor" Y-epsilon , whose values are determined using the approximate expressions. To view the real effects of geometric and kinematic parameters of the gear pair on the tooth root stress analytical model is developed, defining non-dimensional relative stress factor. The analysis comprises two groups of cylindrical gear pairs with different gear ratios and different coefficients of addendum modification. The results obtained are compared with the results of standard calculation procedure according to ISO standard. In addition, the developed analytical model is used to explain the assumptions, physicality and boundary conditions of the "contact ratio factor" Y-epsilon.