Residual stresses and fatigue resistance of toothed wheels

Residual stresses in the dangerous section of toothed wheels made of materials and according to practices accepted in aviation engine construction have been determined using a mechanical method. The influence of the technology of manufacturing of toothed wheels, thermo-chemical treatment, hardening and coating on the residual stresses has been examined. Current technologies of manufacturing toothed wheels lead to significant dispersion of residual stresses, especially after thermo-chemical treatment. Therefore, the results have been statistically processed for each batch of parts and the average values are shown on the residual stress diagrams. We demonstrate the possibility of determining residual stress distribution in the dangerous section of a wheel tooth by the initial deformations of the reference specimen, which makes it possible to keep the part under examination unimpaired. A plate made of the same material as the toothed wheel and hardened simultaneously with the part under examination was used as a reference specimen. The influence of residual stresses on the fatigue resistance of toothed wheels by the average integral residual stresses criterion that takes into account both the value of residual stresses and the nature of their distribution in the dangerous section of toothed wheels was examined.