A System Approach to Contact Fatigue Life Estimation of Right-Angled Geared System

Abstract

The right-angled geared systems are used in automotive and aerospace applications. Most of the right-angled geared systems fail due to contact fatigue. Several articles reported discussing contact fatigue failure of parallel axis geared systems, and the contact fatigue conditions of hypoid and spiral bevel geared systems are seldom studied. This work aims to bridge the gap and proposes a simplified method to model contact fatigue in the right-angled geared system under dry contact conditions. Initially, the gear contact is modeled using a tooth contact analysis methodology for a given load, speed, and operating conditions. The above step is followed by obtaining stress histories based on suitable interpolation conditions, finite element computation, and Hertzian contact conditions. These stress histories form the basis of the Characteristic plane method. The contact fatigue life of the gears is calculated based on the equivalent bending amplitude of a multiaxial stress condition. The equivalent bending amplitude is then used to determine the number of cycles of operation the gear can endure from the SN-curve for that material. This method is then used to perform parametric analysis based on the size, material type, and gear contact ratio.