承力孔孔壁微动磨损对其疲劳性能的影响OA

Bearing holes in service are subjected to multiple loads,and the interaction between the hole wall and mating parts inaxial and circumferential direction induces fretting wear,thereby degrading fatigue performance.To decouple the manifestations of fretting wear and quantify their effects on fatigue,the single-factor experiments of hole-wall surface roughness and residual compressive stress of 7050 aluminum alloy are conducted.Surface roughness and residual compressive stress are controlled via milling and extrusion parameters,followed by high-frequency fatigue testing and fracture observation.Results show that when Ra is within 0.2-0.8 μm,the fatigue life is approximately 30 000 cycles with minor variation,indicating comparable stress-concentration levels under low roughness and a limited influence on life.With the increasing of residual compressive stress,fatigue life increases firstly and decreases;concomitantly,fatigue striation spacing diminishes,reflecting enhanced resistance of the hole wall to cyclic loading.The interference fit of 1.655％yields about a 30％increment of fatigue cycles comparing with the control group.However,excessive extrusion causes near-surface hardening damage and introduces stress concentrators,leading to reduced fatigue life.Overall,fretting-induced fatigue failure of bearing holes is primarily governed by the release of residual compressive stress and wear-induced stress concentration.