Finite element simulations of the high velocity expansion and fragmentation of ductile metallic rings
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摘要: 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ABAQUS/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.
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关键词:
- Grady-Kipp公式
Abstract: In this paper, we numerically simulated the freeexpansion and fragmentation processes of an OFHC ring under an initialvelocity. The conventional Johnson-Cook thermo-viscoplastic constitutivemodel was used to describe the dynamic plastic behavior of the material. TheJohnson-Cook failure model incorporating a cohesive fracture criterion wasused to model the separation progress of the material. ABAQUS/Explicit codewith element erosion was used for the numerical simulations. Multiplesimulations were conducted with a same initial velocity on these meshes,creating a group of fragment samples. The average fragment sizes of eachsample group were obtained. It was found that the Grady-Kipp model based onthe momentum diffusion mechanism gives reasonably close predictions of thefragment sizes; The FEM simulation results show apparent unloading waves(the Mott wave) propagations, confirming that the momentum diffusion didcontrol the 1D ductile fragmentation process.-
Key words:
- Grady-Kipp formula
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