A model for the simulation of the interactions between dynamic tooth loads and contact fatigue in spur gears
Résumé
The main objective of this paper is to study the possible interactions between contact fatigue and dynamic tooth loading in spur gears. To this end, a dynamic gear model is used which incorporates the influence of gear body distortions and simultaneously deals with the equations of motion and the normal contact conditions on tooth flanks. Both crack initiation and propagation are analyzed; crack initiation is studied using several multi-axial fatigue criteria while an approach based on Linear Elastic Fracture Mechanics is employed to analyze the crack propagation period. It is shown that the corresponding fatigue life and defect shape agree well with the evidence from a back-to-back test rig. An extensive parameter analysis is conducted focusing on three characteristic points on the tooth profile, respectively near the root, the pitch point and the tooth tip. The numerical results show that contact fatigue depends on dynamic loads and that tip relief can play an important role in reducing the risk of fatigue at engagement.