Fatigue life of 7075-T651 aluminium alloy treated with vibratory stress relief

As an energy-saving and high-efficient stress relieving process, vibratory stress relief (VSR)'s influence of on fatigue life is still explicit and needs further investigation. Standard specimens are manufactured to study the VSR effects on 7075-T651 aluminium alloy fatigue behaviour. Dynamic stresses generated during vibration are measured by strain gauge, and the residual stresses with and without VSR are compared to validate the stress relieving effects. Eventually, fatigue tests are conducted to obtain the fatigue behaviour of 7075-T651 aluminium alloy treated by VSR with different amplitudes. Experimental results show that when the amplitude is small enough (less than 0.01 mm), the fatigue life is almost unaffected by VSR. Fatigue life increases with the VSR amplitude when the amplitude changes from 0.01 to 0.04 mm. The fatigue limit increases by 11.11% after 0.04 mm amplitude VSR. The fatigue life decreases with the increase of the amplitude when the amplitude changes from 0.05 to 0.1 mm. VSR with 0.1 mm amplitude decreases fatigue life by 11.11%, which should be deliberated in engineering application. It is concluded that low amplitude VSR has positive effects on 7075-T651 aluminium alloy fatigue life, and high amplitude VSR has negative effects.