Aluminum/polytetrafluoroethylene (Al/PTFE) reactive material is a typical multifunctional energetic material, which can release enormous energy under impact loading. To clarify its ignition mechanism, a Split Hopkinson pressure bar (SHPB) is used to conduct the impact ignition experiment on reactive materials with different initial defects. The experimental results show that the measured minimum specific incident energy that can cause the ignition for the specimen without pre‐impact (MSed specimen) increases slowly from 97.5 to 101 Jcm⁻² with the molding pressure first, but drops substantially to 83.3 Jcm⁻² as the molding pressure increases to 100 MPa. In addition, only the MSed specimens with the molding pressure above 100 MPa are ignited at the third stress pulse. Combined with the results of scanning electron microscopy, it is found that the existence of local larger pores inside the MSed specimens with high molding pressures (100, 120, and 150 MPa) contributes to the increase in damage level under impact and thus reduces the ignition threshold. The impact ignition experiment on the pre‐impacted specimens (MSed + PIed specimens) indicates that a phenomenon of damage sensitization exists in Al/PTFE reactive materials, confirming that the initial defects and damage evolution have significant effects on the impact ignition of the material.

中文翻译：

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初始缺陷对铝/聚四氟乙烯反应性材料冲击点火的影响

铝/聚四氟乙烯（Al / PTFE）反应性材料是一种典型的多功能高能材料，在冲击载荷下会释放出巨大的能量。为了阐明其点火机理，使用分裂霍普金森压力棒（SHPB）对具有不同初始缺陷的反应性材料进行冲击点火实验。实验结果表明，在没有预冲击的情况下（MSed样品），可能引起起火的最小能谱比入射能从97.5缓慢增加到101 Jcm ^-2，首先是成型压力，但显着下降到83.3 Jcm ^-2。随着成型压力增加到100 MPa。此外，只有成型压力高于100 MPa的MSed试样在第三应力脉冲下被点燃。结合扫描电子显微镜的结果，发现具有较高成型压力（100、120和150 MPa）的MSed样品内部存在局部较大的孔洞，这有助于增加冲击下的损伤程度，从而减少着火临界点。在预冲击试样（MSed + PIed试样）上进行的冲击着火实验表明，Al / PTFE反应性材料中存在损伤敏化现象，这证实了初始缺陷和损伤演变对材料的冲击着火具有显着影响。