含缺陷厚壁圆管爆轰膨胀断裂的数值模拟

Simulation of the dynamic expanding process of thick-walled cylinder with defects

将金属圆管受到炸药爆轰产物产生的冲击压力简化为直接施加在圆管内壁的压力,通过数值模拟对比分析了计及圆管厚度方向的含缺陷圆管的应力分布影响趋势。结果表明,圆管外表面的缺陷对沿壁厚方向的应力集中影响非常明显,即使只有不到厚度尺寸1/100的微缺陷,圆管最大的等效塑性应变显著增加,甚至可以超出无缺陷时数十倍。这种应力分布造成了圆管从外表面宏观可见裂纹产生到完全贯穿长达十余微秒的断裂过程,从而影响到圆管膨胀断裂实验获得的损伤参数定义的有效性。

The shock pressure on metal cylinder by detonation products is simplified to pressure history straightly loaded on internal wall of the cylinder, the stress distribution in cylinder with defect along the direction of its thickness is analyzed by numerical simulation. The results show the defect on outer surface has remarkable effects on stress concentration in the direction of cylinder thickness. Even with a micro-defect of one percent of cylinder thickness, the maximal equivalent plastic strain of cylinder will be greatly increased, several decuple as large as that of no defect. The stress distribution causes a microseconds rupturing process from crack generating to completely rupture, and affects the validity of damage parameter in metal cylinder expanding fracture experiment.