Design of asymmetric normal contact ratio spur gear drive through direct design to enhance the load carrying capacity

Abstract

Maximum fillet and contact stresses of asymmetric normal contact ratio spur gears designed by direct design method are evaluated based on the load sharing ratio, using finite element method. For a direct gear design, area of existence diagrams are developed for known input gear parameters such as number of teeth, coefficient of asymmetry, top land thickness coefficient and drive side contact ratio. A unique Ansys parametric design language code is developed to find the load sharing ratio, maximum fillet and contact stresses. The fillet stress is calculated in terms of non-dimensional stress. The influence of gear drive parameters such as drive and coast side pressure angles, top-land thickness coefficients, contact ratio, coefficient of asymmetry, gear ratio and teeth number on load carrying capacity has been studied extensively on non-dimensional fillet stress and maximum contact stress and compared with that of the conventionally designed gears. Through parametric study, suitable suggestions are made for the design of asymmetric gear drive for an enhanced load carrying capacity with constant contact ratio and constant drive side pressure angle separately.