修正金属本构模型在超高速撞击模拟中的应用

为更加准确地计算93钨合金弹超高速撞击Q345钢板问题，构建了修正的金属本构模型。引入GRAY三相物态方程描述材料相态变化，采用Johnson-Cook强度模型描述撞击后期材料的力学行为。结合封加波损伤演化模型以及Johnson-Cook失效模型描述不同应力三轴度下材料的拉伸、剪切失效行为；引入曹祥提出的断裂演化模型，描述材料失效后应力归零的过程。通过对比超高速撞击数值模拟结果与实验结果，验证了本构模型的适用性，并进一步分析了典型弹靶撞击条件下破片群的空间分布特征。研究结果表明:基于修正金属本构模型获得的超高速撞击靶板穿孔直径、弹体侵蚀长度、破片群扩展速度结果与实验结果一致；GRAY三相物态方程能够相对准确地给出弹体撞击首层靶板以及剩余弹体、破片群撞击第2层靶板时弹靶材料的熔化情况；封加波损伤演化模型能够准确判断超高速撞击过程中靶板是否产生层裂破坏；综合封加波损伤演化模型、Johnson-Cook失效模型以及曹祥提出的断裂演化模型后，数值模拟获得的破片群撞击后效靶板的穿孔面积与累积数量的统计曲线结果与实验结果一致；获得了典型条件下的柱形93钨弹体超高速撞击Q345靶板破片群空间分布结果，破片群的前端具有较高的质量、轴向动量以及横向动量（绝对值）。

The application of a modified constitutive model of metals in the simulation of hypervelocity impact

To accurately calculate the hypervelocity impact of 93 tungsten alloy projectile on Q345 steel plate, a modified constitutive model of metals is established. The GRAY three-phase equation of state is introduced to describe the phase change of the material, while the Johnson-Cook strength model is used to describe the mechanical behavior of the material in the late stage of impact process. Combined with the Feng’s damage evolution model and Johnson-Cook failure model, the tensile and shear failure behavior of materials under different stress triaxiality are represented. The fracture evolution model proposed by Cao Xiang is adopted to describe the process of stress vanishing after material failure. The applicability of the constitutive model is then verified by comparing the numerical simulation results with the experimental ones. Furthermore, the spatial distribution characteristics of fragment group in a typical process of a projectile impacting target are analyzed. The results show that based on the modified metal constitutive model, the perforation diameter of the target, the erosion length of projectile and the expansion velocity of fragment group of the hypervelocity impact are consistent with the experimental results. The GRAY three-phase equation of state can relatively accurately give the melting situation of the projectile and target materials when the projectile impacts the first layer of the target plate and the remaining projectile and fragment group impact the second layer of the target plate. The Feng’s damage evolution model can accurately judge whether spallation occurs during the hypervelocity impact. After integrating Feng’s damage evolution model, Johnson-Cook failure model and fracture evolution model proposed by Cao Xiang, the statistical curve of perforation area and cumulative number of aftereffect target plate impacted by fragment group obtained from the numerical simulation are consistent with the experiment data. The spatial distribution results of fragment group of cylindrical 93 tungsten projectile hypervelocity impacting Q345 target plate under typical conditions are obtained, and the front part of fragment group possesses high mass, high axial momentum and high transverse momentum by their absolute values.