Effects of Stress Ratios on Aero High-strength LD2CZ Aluminum AlloyFatigue Crack Growth with Corrosion Damage

The effects of stress ratios on fatigue cracks growth of aero high-strength LD2CZ aluminum alloywith corrosion damage were studied with Walker equation with the aid of SS550scanning electron microscopycombined with server hydraulic fatigue test machine.Fatigue tests were executed at stress ratios of 0.05,0.5,0.7for specimens with corrosion damage equivalent to 0,15,30days exposure in certain natural airport environmentrespectively.The fatigue crack growth curves were obtained,and based on that the parameters in Walker equationwere computed out.The results indicate that fatigue cracks growth rate would increase with the increase of stressratio and corrosion damage.According to the obtained Walker equation,the effects of stress ratios and corrosiondamage on the fatigue cracks growth rate could be characterized quantitatively.