Computational design for complex loading on grade density impactor with strain rates of 105~106 s-1
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摘要: 为了在气炮上实现应变率为105~106 s-1的复杂加载技术研究，采用自行研制的拉格朗日程序MLEP(multi-material Lagrangian elastic-plastic)对Al-Cu-W材料体系的阻抗梯度飞片复杂加载不锈钢靶板进行数值模拟，计算设计并分析了阻抗梯度飞片的厚度和密度分布指数对靶板压力、速度和应变率峰值等波形的影响。结果表明：密度指数分布越大，加载时间越短，加载后期的压力、速度和应变率峰值曲线更陡峭；同时, 为了避免靶板/LiF窗口界面反射的稀疏波早于阻抗梯度飞片后界面反射的稀疏波达到碰撞面位置，计算设计中还考虑了飞片厚度的影响。此外，对基于理论设计的阻抗梯度飞片进行了动态考核实验，实验结果基本反映了预期的设计，为材料强度的测量奠定了基础。Abstract: In order to carry out the complex loading research with the strain rates varying from 105 s-1 to 106 s-1 on the light gas gun, we numerically simulated the complex loading on the steel target by the graded ensity impactor (GDI) of Al-Cu-W system using our own developed Lagrangian code MLEP (multi-material Lagrangian elastic-plastic). In our simulation, the effects of the thickness of the GDI and the power exponent of denstiy distribution on the pressure, velocity, and peak strain rate of the target were investigated. The results indicate that the loading time decreases as the power exponent of density distribution increases, and the profiles of pressure, velocity and peak strain rate at the later stage of the loading are steeper than those with smaller power exponents. Moreover, the effect of the thickness of the GDI is considered in our computational design to prevent the confluence of the rarefaction waves emanating from the back of the GDI and the interface between the target and LiF window on the impact interface. Finally, a dynamic test was conducted for the GDI based on the design, and the results show the good agreement between the design and the experiment, which paves the way for the strength measurement of materials in the future.
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Key words:
- solid mechanics /
- complex loading /
- computational design /
- grade density impactor /
- Al-Cu-W system
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图 2 计算设计的Al-Cu-W体系飞片密度分布
Figure 2. Density distribution of Al-Cu-W impactor in computational design
图 3 3种Al-Cu-W体系飞片算例的碰撞面位置压力和速度历史
Figure 3. Profiles of pressure and velocity at impact position
图 4 3种Al-Cu-W体系飞片算例的中心位置压力和速度历史比较
Figure 4. Profiles of pressure and velocity at center
图 5 3种Al-Cu-W体系飞片算例的界面位置压力和速度历史比较
Figure 5. Profiles of pressure and velocity at interface
图 6 靶板中心位置和靶板/LiF窗口界面位置的应变率峰值历史
Figure 6. Comparison of maximum strain rates at center and interface
图 7 带LiF窗口算例中压力随时间和空间的分布
Figure 7. Pressure contours drawn in x-t space with LiF windows
图 8 实验采用4路DPS测量的速度剖面和MLEP计算的速度剖面
Figure 8. Velocity profiles as achieve from experiment by DPS and simulated by MLEP
表 1 3种阻抗梯度飞片主要参数
Table 1. The primary parameters of the three GDIs
实验号 飞片层数 h/mm P 密度分布 1 13 2.1 2 ρ=2.712+4.101x2 2 12 2.1 3 ρ=2.712+2.278x3 3 10 1.8 3 ρ=2.712+3.937x3 
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