负梯度泡沫金属中的局部密实化现象

刘冕; 王根伟; 宋辉; 王彬

doi:10.11858/gywlxb.20190866

负梯度泡沫金属中的局部密实化现象

doi: 10.11858/gywlxb.20190866

刘冕^{1, 2,},
王根伟^{1, 2,*, ,},
宋辉^{1, 2},
王彬^{1, 3}

1.
太原理工大学机械与运载工程学院应用力学研究所，山西太原　030024
2.
材料强度与结构冲击山西省重点实验室，山西太原　030024
3.
伦敦布鲁内尔大学机械航空工程系，伦敦　UB8 3PH，英国

基金项目: 国家自然科学基金（11872265）

详细信息

作者简介:
刘　冕（1996－），女，硕士研究生，主要从事梯度泡沫金属的力学性能研究. E-mail： 516753451@qq.com

通讯作者:
王根伟（1974－），男，博士，副教授，主要从事材料和结构的冲击动力学研究. E-mail： gwang@tyut.edu.cn

中图分类号: O347.3
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出版历程
- 收稿日期: 2019-12-12
- 修回日期: 2019-12-28

Phenomenon of Local Densification in Negative Graded Metal Foam

LIU Mian^{1, 2
,},
WANG Genwei^{1, 2,*
, ,},
SONG Hui^{1, 2},
WANG Bin^{1, 3}

1.
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering of Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
2.
Shanxi Key Laboratory of Material Strength & Structural Impact, Taiyuan 030024, Shanxi, China
3.
Department of Mechanical and Aerospace Engineering, Brunel University London, London, UB8 3PH, UK

摘要

摘要: 基于一维非线性的刚性-塑性硬化模型，研究了在恒速冲击作用下负梯度泡沫的冲击波控制方程和传播特性。采用LS-DYNA有限元软件对三维随机Voronoi技术生成的梯度泡沫金属模型进行数值模拟，验证了理论预测，并定义了冲击波模型下梯度泡沫材料的局部密实化应变与第二临界速度。通过对冲击速度、密度梯度、相对密度参数的影响研究发现：冲击波模型的理论解与有限元模型的数值解吻合较好，基于R-PH模型的冲击波理论能较好地预测负梯度泡沫金属的力学性能；局部密实化应变在不同冲击速度下存在3个增长阶段；密度梯度绝对值和相对密度越大，局部密实化应变越小，第二临界速度越大。最后讨论了负梯度泡沫中局部密实化现象对支撑端应力的影响。
- 梯度泡沫金属 /
- 冲击波 /
- 局部密实化应变 /
- 第二临界速度
Abstract: Based on the one-dimensional nonlinear rigid-plastic hardening (R-PH) model, the control equations and mechanical response characteristics of the shock wave propagation of the negative graded foam under constant velocity impact are studied. The LS-DYNA finite element software is used to numerically simulate the graded metal foam model generated by the three-dimensional stochastic Voronoi technology to verify the theoretical prediction. The local densification strain and the second critical velocity of the graded foam material under the shock wave model are defined. By studying the effects of impact velocity, density gradient and relative density parameters, it is found that the theoretical solution of the shock wave model is in good agreement with the numerical solution of the finite element model. The shock wave theory based on the R-PH model can better predict the negative graded foam metal. The mechanical properties of the local densification strain have three growth stages at different impact velocities; the larger the absolute value of the density gradient and the relative density, the smaller the local densification strain and the larger the second critical velocity. Finally, the effect of local densification on the stress at the support end in the negative graded foam is explained.
- graded metal foam /
- shock wave /
- local densification strain /
- the second critical velocity

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图 1 双波模型

Figure 1. Double shock model

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图 2 有限元模型

Figure 2. Finite element model

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图 3 不同相对密度的准静态应力-应变曲线和参数拟合结果

Figure 3. Quasi-static stress-strain curve and parameter fitting results with different relative densities

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图 4 不同冲击速度下的v_u曲线

Figure 4. Curves of v_u at different impact velocities

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图 5 不同冲击速度下波阵面的位置曲线

Figure 5. Location of wave front at different impact velocities

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图 6 负梯度泡沫的名义应力-应变曲线与能量吸收效率曲线

Figure 6. Nominal stress-strain curve and energy absorption efficiency curve of negative graded foam

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图 7 负梯度泡沫的应变云图

Figure 7. Strain nephograms of negative graded foam

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图 8 两端应力的FE结果和理论预测对比

Figure 8. Comparison of FE results and theoretical predictions at both sides stress

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图 9 密度梯度与相对密度对局部密实化应变的影响

Figure 9. Influence of density gradient and relative density on local densification strain

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图 10 不同密度梯度和相对密度下的变形模态

Figure 10. Deformation modes under different density gradients and relative densities

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图 11 不同冲击速度下支撑端的名义应力-应变曲线

Figure 11. Nominal stress-strain curve of the support end under different impact velocities

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图 12 不同冲击速度下冲击端与支撑端的名义应力-应变曲线

Figure 12. Nominal stress-strain curves of the impact end and the support end under different impact velocities

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表 1 本构模型参数

Table 1. Constitutive model parameters

ρ_s/(kg·m^–3) E/GPa ν σ_ys/MPa E_t/GPa

2 700 69 0.3 76 0.69

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