Multiaxial fatigue behavior of aluminum alloy thin-walled notched specimens based on DIC

Abstract

Focusing on the influence of notch on the multiaxial fatigue performance of material, the proportional multiaxial fatigue test was carried out on 7075-T651 aluminum alloy thin-walled notched specimens with variable equivalent stress amplitude. The digital image correlation technique was used to characterize and analyze the critical plane angle. The results show that with the increase of the equivalent stress amplitude, the multiaxial fatigue life of the specimen decreases, and the maximum axial, torsional and shear engineering strains near the notch increase. Under different loading conditions, the strain concentration near the notch increases with the increase of loading cycles. The process of strain change near the notch can be divided into crack initiation, crack growth and instantaneous fracture stages. By introducing the critical plane angle and the maximum positive strain on it, a modified SWT model is proposed. Fine life prediction results are obtained by the modified model with all predicted data in the two scatter bands.

Keywords

• 7075-t651 aluminum alloy
• notched specimen
• multiaxial fatigue
• failure mechanism
• life pre- diction