在爆炸及高速碰撞的有限元模拟中，往往涉及到材料的大变形、断裂过程． 文中 选取 2A97 铝锂合金材料，针对 Johnson-Cook(J-C)失效模型，对获取相应失效参数的方法 进行了研究;设计了不同缺口尺寸的试样，结合有限元模拟对缺口试样的应变分布和应力 三轴度进行了研究，发现缺口试样的最大应变集中于缺口表面处，得到了缺口表面处应力 三轴度在加载过程中的变化情况． 基于此结果，文中还制作了细散斑，并通过二维数字图 像相关(DIC)测量方法得到了常温至573K 下准静态及动态加载试样的失效应变，从而准 确地将修正应力三轴度、应变率和温度与失效应变对应起来，获取了更为准确的 J-C 失效 模型参数;通过对铝锂合金断口使用 SEM 扫描电镜进行微观观察，探究了应力三轴度影 响铝锂合金失效应变的微观机理，发现材料在变形过程中产生的微孔洞随应力三轴度的 增大而不再大量聚集形成韧窝．

The finite element simulations of explosion and high-speed collision often involve the process of large deformation and fracture of materials． The 2A97 Aluminum-Lithium (Al-Li) alloy was selected to investigate the Johnson-Cook (J-C) failure model，and the new experimental and numerical framework for determining of revised J-C failure parameters was conducted． The specimens with different notch sizes were designed，and the strain distri- bution and stress triaxialities of the notch samples were studied by using the finite element simulation． Results show that the maximum strain of the notch samples was concentrated at the notch surface，and the variations of stress tri- axialities at the notch surface during the loading process were obtained． Based on the results，the fine speckle was made，and the failure strains of the quasi-static and dynamic loading samples under 293K －573K were obtained by 2D digital image correlation (DIC) measurement method． Thus，the revised stress triaxialities，strain rate and temperature were accurately corresponded to the failure strains，which helps to obtain the accurate J-C failure parameters． In addition，the fracture of Al-Li alloy specimen was observed by SEM，and the microcosmic mechanism of effect of stress triaxiality on the failure strain of Al-Li alloy was investigated． Results show that the micropores produced in the deformation process no longer accumulate into dimples with the increase of stress triaxiality．