Fracture behaviors of explosively driven TA2 alloy cylinders under different loadings
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摘要: 金属柱壳破坏过程与材料、结构及载荷等相关，断裂结果呈现多种形式，采用有限元结合实验对不同爆炸载荷作用下，TA2钛合金圆管的破坏机制开展研究。有限元结果显示：对于理想均质柱壳，由于冲击波传播使壁厚中间形成二次塑性区，圆管壁厚中部的等效塑性应变总是大于内、外壁。在较高爆压下，裂纹在加载阶段从试样壁厚中部起始，沿45°或135°向内外壁剪切扩展；而在较低爆压下，破坏发生在自由膨胀阶段，断裂从内壁起始向外壁剪切扩展，两者破坏过程和机制不同，总体来说，与实验现象符合较好。相关实验中出现的一些外壁拉伸断裂现象，可能与试样的几何、材料缺陷等因素相关，其对金属圆管爆炸破坏的影响值得进一步关注。Abstract: The failure process of an explosively driven TA2 alloy cylinder is related with its material, structure, loading, and so on, with its fracture behavior shown in various ways. In this paper we investigated the mechanism underlying this failure under different explosive loadings using numerical and experimental methods. The results of the finite element analysis showed that, during the driven period, for the ideally homogeneous cylinder, the equivalent plastic strain effect in the inner zone of the cylinder's thick shell, where the secondary plastic zone was formed due to shock wave propagation, was always larger than that on the inner and outer surfaces; under higher blast loading, the cracks originated first in the secondary plastic zone during the driven period and propagated to the inner and outer surfaces in an angle of 45° or 135° to the radial; for lower blast loading, the shear cracks, which originated first in the inner surface, propagated to the outer surface in an angle of 45° or 135° to the radial during the free expanding period; and, although the cracks were all shear cracks, their failure mechanisms differed. The simulated results and experiments agreed pretty well. The phenomenon that cracks originated in the outer surface, as reported earlier concerning some related experiments, might have been affected by the specimens' geometrical and material defects, whose influence on the cylinder's explosion-induced failure needs to be studied further.
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Key words:
- metal cylinder /
- explosive load /
- defect /
- finite element model
1) “第十一届全国爆炸力学学术会议”推荐论文 -
图 1 平面应变圆管爆炸加载模型
Figure 1. Finite element model of metal cylinder subjected to explosive load
图 2 圆管膨胀、破坏过程等效塑性应变演化
Figure 2. Equivalent plastic strain evolution of circular tube during expansion and failure
图 3 圆管外壁在不同爆轰载荷下的速度时程曲线
Figure 3. Histories of explosive load and outer surface velocity of circular tube under explosive load
图 6 高爆轰压力下沿壁厚各点应力时程曲线
Figure 6. Histories of stressalong thickness under higher pressure
图 7 高爆轰压力下沿壁厚等效应变演化特性
Figure 7. Development of equivalent plastic strain under higher pressure
图 8 低爆轰压力作用下内壁应力时程曲线
Figure 8. Histories of stress along thickness under higher pressure
图 9 低爆轰压力下等效应变演化发展特征
Figure 9. Development of equivalent plastic strain under lower pressure
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