韧性金属圆环高速膨胀碎裂过程的有限元模拟

FINITE ELEMENT SIMULATIONS OF THE HIGH VELOCITY EXPANSION AND FRAGMENTATION OF DUCTILE METALLIC RINGS

用数值方法模拟了韧性金属圆环的自由膨胀碎裂过程.采用Johnson-Cook热黏塑性本构模型描述材料的动态变形和热软化特性,采用包含内聚力失稳断裂准则的Johnson-Cook型损伤断裂模型描述材料的破坏和分离过程,采用结合单元消去技术的A.BAQUS/Explicit程序进行分析.在特定膨胀速度下对多个圆环进行碎裂数值实验,获得碎片样本集合.研究证实,Grady-Kipp基于塑性卸载波传播机制的韧性碎片尺寸公式可以较好地预测碎片的平均长度.模拟再现了圆环碎裂过程中塑性卸载波的传播,揭示了Grady-Kipp公式合理性的物理基础.

In this paper, we numerically simulated the free expansion and fragmentation processes of an OFHC ring under an initial velocity. The conventional Johnson-Cook thermo-viscoplastic constitutive model was used to describe the dynamic plastic behavior of the material. The Johnson-Cook failure model incorporating a cohesive fracture criterion was used to model the separation progress of the material. ABAQUS/Explicit code with element erosion was used for the numerical simulations. Multiple simulations were conducted with a same initial velocity on these meshes, creating a group of fragment samples. The average fragment sizes of each sample group were obtained. It was found that the Grady-Kipp model based on the momentum diffusion mechanism gives reasonably close predictions of the fragment sizes; The FEM simulation results show apparent unloading waves （the Mott wave） propagations, confirming that the momentum diffusion did control the 1D ductile fragmentation process.