Theoretical analysis of the influence of pore collapse behavior on the shock compression characteristics of porous materials
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摘要: 多孔材料在冲击压缩过程中伴随着孔隙坍塌行为,本文基于前人开展的试验中所观测到的冲击波结构,对多孔材料的冲击波形成过程及孔隙坍塌行为间的联系进行了理论分析。首先,考虑多孔材料的压缩曲线特性和冲击波追赶问题,提出了多孔材料的冲击波结构存在低压单波模式、双冲击波模式和、高压单波三种模式。进一步,结合Wu-Jing物态方程发展了与不同冲击波模式相容的冲击压缩特性计算方法,得到了与单冲击波模式相容的冲击比容计算方程,可以无需采取近似条件直接计算临界比容。此外,通过对弹性阶段与弹塑性阶段材料的孔隙度随压力的变化规律采取线性近似,并考虑了多孔材料中基体材料受力与宏观应力之间的关系,修正了Carroll建立的孔隙坍塌关系方程。基于本文发展的考虑孔隙坍塌行为的冲击压缩特性计算模型,对材料的Hugoniot数据进行了计算,讨论了孔隙坍塌行为对多孔材料冲击压缩特性的影响。结果表明在较低压力时材料的冲击物态特性受孔隙坍塌行为影响明显,本文模型能够更加精确地预测多孔材料的冲击波参量。
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关键词:
Abstract: Porous materials are accompanied by pore collapse behavior during impact compression. Based on the shock wave structure observed in previous experiments, this paper theoretically analyzes the relationship between the shock wave formation process and pore collapse behavior of porous materials. Firstly, considering the compression curve characteristics of porous materials and the overtaking of shock wave, it is proposed that the shock wave structure of porous materials has three modes : low pressure single wave mode, double shock wave mode and high pressure single wave mode. Furthermore, combined with the Wu-Jing equation of state, the calculation method of shock compression characteristics compatible with different shock wave modes is developed, and the calculation equation of impact specific volume compatible with single shock wave mode is obtained, which can directly calculate the critical specific volume without approximate conditions. In addition, the equation of pore collapse established by Carroll is modified by taking the linear approximation of the variation of porosity with pressure in the elastic stage and the elastic-plastic stage, and considering the relationship between the stress of the matrix material and the macroscopic stress in the porous material. Based on the calculation model of shock compression characteristics considering pore collapse behavior developed in this paper, the Hugoniot data of the material are calculated, and the influence of pore collapse behavior on the shock compression characteristics of porous materials is discussed. The results show that the shock compression characteristics of the material are significantly affected by the pore collapse behavior at lower pressures, and the model in this paper can predict the shock wave parameters of porous materials more accurately.-
Key words:
- porous material /
- mechanics of explosion /
- Wu-Jing model /
- shock wave structure /
- pore collapse
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