Effect of loading history on stress-strain relationship of expanding ring Guo Zhaoliang, Fan Cheng, Liu Mingtao, Tang Tiegang, Liu Cangli
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摘要: 利用两类实验装置开展了无氧铜TU1膨胀环实验研究，发现：电磁膨胀环在加载阶段，样品受体力作用，满足均匀变形的假定；而爆炸膨胀环在加载阶段，样品内壁受面力冲击作用，不满足均匀变形的假定。针对这个差异，发展了一种考虑冲击阶段变形不均匀性的新方法，利用回收样品几何变形，将冲击阶段试样环内轴向塑性应变、径向塑性应变纳入等效塑性应变的计算中，通过修正后的方法更准确地获得了材料的应力应变关系。Abstract: Electromagnetic driving expanding ring experiment and explosive expanding ring experiment are two important means for obtaining dynamic tensile mechanical properties of materials. In this study, they were carried out to investigate the dynamic behaviors of oxygen-free copper (TU1) expanding rings. The results show that, during the loading stage, samples driven by electromagnetic force satisfy the assumption of the uniform deformation due to the body force whereas it is not the case with the explosive expanding ring because the sample is impacted by the surface force. With respect to this difference, a new method considering the deformation inhomogeneity was established, where the axial plastic strain and radial plastic strain during impact stage was included in the calculation of the equivalent plastic strain. Through the revised method a more accurate stress-strain relationship of TU1 was obtained.
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图 5 爆炸膨胀环的环向应变、径向应变、轴向应变及等效塑性应变
Figure 5. Explosive expanding ring's hoop strain, axial strain, radial strain and effective strain
图 6 膨胀环的应力应变关系
Figure 6. Relationship between expanding ring's flow stress and effective plastic strain
表 1 膨胀环实验数据
Table 1. Experimental data of expanding rings
加载方式 U/kV ${\tilde h}$/mm ${\tilde \delta }$/mm ${{\tilde \varepsilon }_\theta }$/% ${{\tilde \varepsilon }_z}$/% ${{\tilde \varepsilon }_r}$/% (ΔU/U)/% 3.5 1.90 0.96 14.46 -6.12 -6.06 2.28 电磁 4.0 1.83 0.93 21.96 -9.88 -9.24 2.84 4.5 1.77 0.89 29.50 -13.21 -13.63 2.66 爆炸 - 外 内 0.812 12.25 外 内 -22.81 - 2.078 2.408 2.83 17.57 
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