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The extent of damage that is developed during the production, transportation, storage, and handling of propellants after a low-velocity impact is an important factor in evaluating a dangerous threat such as deflagration-to-detonation transition. In this paper, a friability test was performed to evaluate the critical impact ignition velocity ( CIIV), fragmentation degree, and potential reaction violence of four 3, 3-Bis(azidomethyl)oxetane (BAMO) and tetrahydrofuran (THF) copolymer-propellants (PBT-propellants) with various 3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) contents under impact at different velocities. The results showed that as the HMX contents increased, the CIIV decreased and changes of that also decreased. Simultaneously, the fragmentation degree increased with the increase in impact velocity, as it was judged by the initial dynamic activity ratio. Then, we calculated the maximum value of the initial dynamic activity ratio by fitting the data using Boltzmann, which were 27 (HMX = 0), 39 (HMX = 5%), 48 (HMX = 10%), and 56 (HMX = 15%). The ratios of the maximum value of the initial dynamic activity ratio between PBT-propellants containing HMX and those without HMX were 1.44, 1.78, and 2.07. The addition of HMX increased the maximum fragmentation degree of PBT-propellants under impact. The potential reaction violence increased as the impact velocity increased due to the increase in the fragmentation degree of PBT-propellants after impact. Similarly, we also obtained the maximum values of potential reaction violence, which were 62.39, 50.17, 41.89, and 34.65. The maximum value of potential reaction violence decreased with the increase in HMX contents, and the addition of HMX improved the safety of PBT-propellants burning after impact.

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In order to analyze the influence of a water medium on the forming process and penetration performance of a shaped charge jet, a comparative study was carried out on an underwater shaped charge jet (USCJ) and a shaped charge jet (SCJ) in air. The virtual mass hypothesis is proposed to analyze the forming mechanism of USCJs. The arbitrary Lagrangian–Eulerian algorithm is adopted to carry out a series of simulation calculations considering the impact of standoff height and liner cone angle. The penetration test of the shaped charge jet in two media is carried out, and the experimental results verify the effectiveness of the theory and simulation. The differences of SCJ formation and penetration in air and water are analyzed. The results demonstrate that the USCJ exhibits a higher jet head velocity, higher cumulative kinetic energy, and a greater penetration ability than those of the jet in air. The depth of penetration (DOP) initially increases and subsequently decreases with an increase in the standoff height. The optimal standoff height of the USCJ is approximately 4–4.5 times greater than the charge diameter, whereas the SCJ in air is approximately 3.5–4 times greater than the charge diameter. Additionally, the DOP of the jet decreases at the optimal standoff height with an increase in the cone angle.