爆炸成型弹丸成型过程中的断裂数值模拟及机理分析

Numerical Simulation and Mechanism Analysis of EFP's Fracture in Forming Process

为研究爆炸成型弹丸(EFP)轴向断裂机理,采用有限元分析软件LS-DYNA,引入Johnson-Cook失效模型及自适应算法,对典型EFP装药结构不同外曲率球缺形药型罩OFHC铜EFP成型过程中的断裂进行数值模拟,并通过实验进行验证。采用应力波理论分析了长杆形EFP轴向断裂机理并确定了速度梯度断裂临界值。研究结果表明:基于Johnson-Cook失效模型及自适应算法,采用LS-DYNA软件可较好地模拟EFP成型过程中的断裂现象;对于特定EFP装药结构的球缺形药型罩,存在药型罩曲率临界值使长杆形EFP发生轴向断裂;应力波理论计算所得速度临界值(60~83 m/s)与数值模拟所得EFP速度梯度断裂临界值(76 m/s)吻合较好。该研究结果对OFHC铜EFP的设计具有参考意义,理论分析方法可应用于确定长杆形EFP的速度梯度断裂临界值,并为新材料在EFP药型罩中的应用提供参考。

In order to study the fracture mechanism of explosively-formed projectile （EFP） in axial direc- tion, the forming and fracturing processes of OFHC EFP with typical charge structure are simulated by u- sing LS-DYNA software, in which Johnson-Cook failure model and adaptive algorithm are introduced. Hemispherical liners with different extrinsic curvatures are simulated, and the simulated results of fracture are validated through experiment. The stress wave theory is used to analyze the fracture mechanism of long rod EFP, and confirm the critical velocity gradient. The results show that the fracture phenomenon of EFP can be well simulated by using LS-DYNA software based on Johnson-Cook failure model and adap- tive algorithm. For certain EFP charge structure with hemispherical liner, a critical liner curvature which makes the long rod EFP fracture in forming process exists. The critical value of 60 - 83 m/s calculated from stress wave theory agrees well with the critical velocity gradient （76 m/s） of EFP fracture. The the- oretical analysis method can be used to confirm the critical velocity gradient of long rod EFP fracture.