Statistical Law of Dynamic Fracture Strain Distribution of 6061 Aluminum Electromagnetic Expansion Ring
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摘要: 研究延性金属环在动态加载下的断裂应变分布规律具有重要意义，电磁膨胀环装置是常用的实验加载手段。然而，目前实验上缺乏有效的原位观测技术，无法获得高精度的断裂应变统计数据。为此，将新研制的密排光子多普勒测速仪阵列应用于电磁膨胀环实验，获得了大量高置信度的断裂应变实验数据；通过硬度测量获得了材料屈服强度的统计分布规律，建立了含概率的本构模型，并进行了大规模计算，得到了大量的断裂应变模拟结果。结合实验与模拟结果，分析了6061铝电磁膨胀环动态断裂应变的应变率效应以及断裂应变韦伯分布假设的合理性。
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关键词:
- 密排多普勒测速仪阵列 /
- 电磁膨胀环 /
- 断裂应变统计规律 /
- 应变率效应
Abstract: The fracture strain distribution of ductile metal rings under dynamic loading has significant application value, and the electromagnetic expansion ring is a commonly used experimental loading method. However, currently there is a lack of effective in-situ observation technology in experiments, making it impossible to obtain high-precision fracture strain statistical data. In this paper, the newly developed close-packed photonic Doppler velocimetry (PDV) array testing technology was applied to the electromagnetic expanding ring experiment, and a large amount of high-confidence fracture strain experimental data were obtained. The statistical distribution of material yield strength was obtained through hardness measurements, a probabilistic constitutive model was established, and large-scale computations were carried out to obtain a wealth of fracture strain simulation results. By combining experiments with simulations, the strain rate effect of dynamic fracture strain in 6061 aluminum electromagnetic expanding ring and the rationality of the Weibull distribution assumption for fracture strain were analyzed. -
图 1 (a)密排PDV阵列测点布局及装配实物，(b)膨胀环实验装置原理
Figure 1. (a) Densely packed PDV array measurement points and assembly of the experimental setup; (b) principle of the expansion ring experimental device
图 4 (a) 40.1 μs和 (b) 43.1 μs时刻6061铝电磁膨胀环的高速摄影照片
Figure 4. High-speed photographs of the electromagnetic expansion ring made of 6061 aluminum alloy at 40.1 μs (a) and 43.1 μs (b)
图 5 6061铝电磁膨胀环断裂应变的实验测量结果
Figure 5. Experimental measurement results of the fracture strain for electromagnetic expansion rings
图 6 6061铝电磁膨胀环实验数据统计分布
Figure 6. Cumulative frequency distribution curve of the electromagnetic expansion ring experimental data
图 8 6061铝样品的维氏硬度测量界面
Figure 8. Vickers hardness measurement interface of the 6061 aluminum ring
图 9 6061铝环的维氏硬度频率分布
Figure 9. Vickers hardness frequency distribution of the 6061 aluminum ring
图 11 6061铝电磁膨胀环数值模型断裂应变累计频率分布
Figure 11. Cumulative frequency distribution of the fracture strain of numerical simulation models for the 6061 aluminum electromagnetic expansion ring
表 1 实验样品的最大扩展速度及断口数量
Table 1. Maximum expansion velocity and number of fractures of experimental samples
Test No. Charging voltage/kV Maximum expansion velocity/(m·s–1) Number of fractures 1 5.25 113 1 2 5.50 120 3 3 5.50 130 4 4 6.00 145 4 5 6.00 150 6 6 6.25 175 10 7 6.50 190 8 
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表 2 6061铝的J-C模型参数
Table 2. Parameters of the J-C model of the 6061 aluminum
ρ/(g·cm−3) G/GPa A/GPa B/GPa n C $ \dot{\varepsilon}_0/\mathrm{s}^{-1} $ Tm/K Tr/K m cp/(J∙kg−1∙K−1) 2.703 27 0.278 0.245 0.817 0.0256 1.0 925 300 1.34 876
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