Three dimensional fatigue crack initiation and propagation analysis of a gear tooth under various load conditions and fatigue life extension with boron/epoxy patches

Three-dimensional finite element analyses were conducted to study both crack initiation and propagation in a gear tooth. A damage mechanics approach was used to model crack initiated on the surface of a gear tooth due to rolling contact fatigue (RCF). A finite element model was developed to study the effects of friction on the fatigue crack initiation life. After the location of crack initiation was identified, a fracture mechanics approach was employed to simulate mixed-mode fatigue crack propagation. Partial contact loading conditions were also considered based on the width of the contact load acting along the thickness.