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摘要: 为研究金属粉末在冲击加载过程中, 粉末预压力对压坯动态力学响应的影响, 设计了基于分离式霍普金森压杆装置(split Hopkinson pressure bar, SHPB)的金属粉末高应变率冲击加载实验, 并结合一维应力波理论对预压后粉末压坯的力学性能进行分析。结果表明:在冲击过程中, 金属压坯会表现出较为明显的应变率效应; 加载率越大, 材料的应变能越大, 预压力越大, 应变硬化率越大; 在相同的加载条件下, 预压力越大, 压坯临界位移越小。Abstract: A split Hopkinson pressure bar (SHPB) test system was designed to study the dynamic mechanics performance of metal particle by impact loading. The powder mechanical properties were analyzed by one-dimensional stress wave theory. The results show an obviously strain rate effect in the impact compaction process. As the pre-pressure increases, the faster loading rate results in the larger material strain energy, and the strain hardening rate is higher. The critical displacement of green-compacts is decreased with the increase of pre-pressure under the same loading condition.
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Key words:
- impact loading /
- metal powder /
- strain rate /
- pre-pressure /
- Hopkinson pressure bar
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图 1 传统霍普金森压杆示意图
Figure 1. General arrangement of a conventional split Hopkinson pressure bar
图 3 20 kN预压后铁粉在冲击加载条件下的波形曲线
Figure 3. Original wave of ferrous powder after 20 kN precompaction under impact loading condition
图 6 预压过程中三种材料的力–位移曲线
Figure 6. Force-displacement of three materials curve during precompaction
图 7 铝粉(a)和铜粉(b)压坯相对密度变化情况
Figure 7. Relative density of aluminium powder (a) and copper powder (b)
图 8 15 kN预压后的铜粉在不同加载速率下的应力–应变曲线
Figure 8. Stress–strain curve of copper powder after 15 kN precompaction under different loading velocities
图 9 20 kN预压后铁粉在不同加载速率下的应力–应变曲线
Figure 9. Stress–strain curve of ferrous powder after 20 kN precompaction under different loading velocities
图 10 应变能随着加载速率的变化情况
Figure 10. Change of strain energy under different impact velocities
图 11 不同预压条件下铜粉应力–应变曲线
Figure 11. Stress–strain curve of copper powder under different pre-pressure condition
图 12 Al粉在不同入射压力下的力–位移曲线
Figure 12. Force-displacement curve of aluminium powder under different loading condition
图 13 不同加载条件下临界位移随预压力的变化情况
Figure 13. Change of critical displacement with precompaction force under different loading condition
表 1 铜粉中各元素的化学成分(质量分数)
Table 1. Chemical composition of electrolytic copper powder
% Cu Fe Pb As Sb O Bi Ni Sn Zn S Cl 氢损 99.800 0.020 0.050 0.010 0.010 0.150 0.002 0.003 0.004 0.004 0.004 0.004 0.100 
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表 2 铁粉中各元素的化学成分(质量分数)
Table 2. Chemical composition of reduced iron powder
% Fe Mn Si C S HCl不溶物 氢损 ＞98.000 0.300 0.110 0.024 0.020 0.450 0.310
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表 3 铝粉中各元素的化学成分(质量分数)
Table 3. Chemical composition of aluminite powder
% Al Cu Fe Si 水份 99.8000 0.0014 0.0908 0.0409 0.0100
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