Data processing method for bidirectional-load split Hopkinson compression bar
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摘要: 本文中提出单轴双向加载分离式霍普金森压杆（bidirectional-load split Hopkinson compression bar，BSHCB），即在传统的分离式霍普金森压杆（split Hopkinson pressure bar，SHPB）的基础上增加另一个对称的入射波，两边的入射波同时且对称地对试样进行动态加载。根据一维应力波传播理论，推导出单轴双向加载分离式霍普金森杆的数据处理公式。通过数值模拟分析发现，所推导的数据处理公式可以用于计算单轴双向加载实验中试样的工程应力、工程应变和工程应变率。此外，单轴双向对称加载不仅可缩短试样内部应力均匀化的过程，而且可以提高试样应变率。Abstract: This paper presents a bidirectional-load split Hopkinson compression bar (BSHCB), namely, adding other symmetrical incident wave on the basis of traditional split Hpkinson pressure bar (SHPB), the two incident waves would load the specimen synchronously and symmetrically. The data process equations are approached according to the one-dimensional stress wave theory. According to the numerical simulation analyses, it is concluded that the proposed data process equations can determine the engineering stress, engineering strain and engineering strain rate of the tested material in bidirectional-load split Hopkinson compression test. Moreover, compared with the traditional SHPB test, the specimens in bidirectional-load split Hopkinson compression test can reach constant stress state in shorter time, and the strain rate can be improved.
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Key words:
- bidirectional load /
- Hopkinson pressure bar /
- stress equilibrium /
- strain rate /
- data processing
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图 1 BSHCB示意图
Figure 1. Sketch map of the bidirectional-load split Hopkinson compression bar
图 3 试样内部单元分组和编号以及试样内部各组单元的平均应力-应变曲线
Figure 3. Grouping and serial numbers of specimen elements, and average stress-strain curve of each element group
图 4 300 MPa VS 300 MPa BSHCB模拟中所采集的应力波信号及数据处理所用的波形
Figure 4. Stress waves and data processing waves used in BSHCB simulation of 300 MPa VS 300 MPa
图 5 300MPa VS 300MPa BSHCB的工程应力-工程应变曲线的计算结果与模拟结果的比较
Figure 5. Comparison of calculated and simulated stress-strain curves in BSHCB simulation of 300 MPa VS 300 MPa
图 6 BSHCB和传统SHPB实验中试样内部的应力均匀性比较
Figure 6. Comparison of stress equilibrium in specimens of BSHCB and SHPB tests
图 7 BSHCB实验中的恒应变率加载模拟结果
Figure 7. Simulation results of constant strain-rate loading in BSHCB test
图 8 单向加载与双向加载结果对比
Figure 8. Comparison between the results of traditional and bidirectional-load methods
图 9 不对称加载时2024铝动态力学性能的计算结果
Figure 9. Calculated results of 2024 aluminum alloy dynamic properties when the loadings are asymmetrical
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