Influences of finite element model load distribution and load sharing on fatigue crack propagation behaviour of spur gear

Abstract

Spur gears are considered to be the most important mechanical element for transmitting the power between parallel shafts with the small centre distance. The preliminary stage of spur gear tooth design is carried out considering the limit of load rating. Tooth fracture is an important failure mode when the tooth was loaded by bending fatigue load. In most of the literature, failure predictions are approximated by using either Two-Dimensional (2D) Finite Element (FE) based moving load model with point load or Three-Dimensional (3D) FE based moving load model with Uniformly Distributed Load (UDL). In this research work, the main objective is to estimate the actual crack propagation failure at the tooth root by developing reliable FE models of Normal Contact Ratio (NCR) (contact ratio lt 2) spur gear and Actual Load Distribution (ALD) model. A generalised mathematical model is required to explore the Load Distribution Ratio (LDR) along the face width and Load Sharing Ratio (LSR) between the pair of gear tooth using different FE models. The 3D FE models of Single Tooth Part Model (STPM), Three Teeth Part Model (TTPM), Three Teeth Full-rim Model (TTFM) have been created to find the actual crack propagation failures of three types of gear dimensions referred to as Type 1, Type 2, and Type 3 spur gear using ABAQUS software. The stiffness-based mathematical model has been implemented to find the LDR (from each nodal deflection of the contact line) and the LSR which is used to estimate the ALD model newline