2198-T8 aluminum-lithium alloy is an advanced aeronautical engineering material. The multiaxial fatigue tests of notched specimens are conducted with the variables of notch diameter, notch number, and equivalent stress amplitude, respectively. The strain field and fatigue life are characterized and calculated by digital image correlation (DIC) technique. The results show that: the fatigue life decreases with the increase of notch diameter, number of notches, and the equivalent stress amplitude. The strain curves calculated by VIC-3D are similar to those obtained by the testing. The normal and shear strain concentration becomes obvious at 80% to 90% fatigue life, and the surface cracks appear at 95% fatigue life, typical multiaxial fatigue morphologies including tire patterns and wear fatigue striations are observed on the fracture surface. The feasibility of the DIC technique to characterize multiaxial fatigue behavior is verified. The modified SWT model provides fine life prediction results with all predicted data within a factor of two.

2198-T8铝锂合金是一种先进的航空工程材料。缺口试样的多轴疲劳试验分别以缺口直径、缺口数和等效应力幅为变量进行。通过数字图像相关（DIC）技术对应变场和疲劳寿命进行表征和计算。结果表明：疲劳寿命随着缺口直径、缺口数量和等效应力幅的增加而降低。VIC-3D 计算得到的应变曲线与试验得到的相似。疲劳寿命80%～90%时法向应变和剪应变集中明显，95%疲劳寿命时出现表面裂纹，断面上观察到典型的多轴疲劳形貌，包括轮胎花纹和磨损疲劳条纹。验证了 DIC 技术表征多轴疲劳行为的可行性。修改后的 SWT 模型提供了精细的寿命预测结果，所有预测数据都在两倍的范围内。