Influence of laser-induced discrete hardening units on gear surface fatigue resistance: Investigation from contact behavior and lubrication state

Abstract

High-energy-density gears demand enhanced wear resistance and fatigue strength that traditional surface treatments struggle to balance. This study introduces laser-induced discrete hardening units (DHUs) to create a soft–hard alternating structure on gear tooth surfaces. Gear meshing tests reveal that DHUs reduce frictional power by 9.36–27.10 % and stabilize the running-in phase. Finite element simulations indicate a 43.9–49.0 % increase in maximum equivalent stress in hard zones while lowering substrate stress. Moreover, numerical analysis shows a 0.29 % improvement in oil film thickness and a 15.6 % decrease in oil film pressure. These combined effects enhance lubricant retention, mitigate substrate wear, and improve contact fatigue performance, ultimately extending gear lifespan and offering valuable insights for fatigue-resistant gear design in applications.