Residual Stress Evolution and Stability: Assessing Heterogeneity and Relaxation in Gear Operation

Resumo

Copyright © (2025) by American Gear Manufacturers Association. All rights reserved.This study addresses the sensitive aspects of the residual stress heterogeneity and its impact on the relaxation phenomena during the gear's operation. The primary objective is to evaluate how the operational loads can change the residual stress state due to the initial heterogeneity, specifically aiming to correlate the impact of these changes within the gear lifetime. Fatigue tests were performed, in which samples with different conditions of number of cycles were evaluated to observe the residual stress relaxation. This approach enabled the evaluation of the residual stress stability of the samples based on the evolution of the residual stress state. Aspects such as contact pressure, cyclic deformations, and retained austenite transformation were considered to evaluate the shakedown. Preliminary results of the surface residual stress relaxation have already provided relevant information related to the tendency for relaxation during gear operation due to a higher heterogeneity level. The comprehensive analysis of the residual stress state highlights the potential to optimize the gear manufacturing chain. With that, this approach can make it possible to understand and achieve more stable residual stress profiles in gears, ensuring their benefits are maintained for a long period throughout the gear's lifetime.