Initiation of a Confined Finite‐Thickness Explosive under the Impact of Shaped Charge Jet

Abstract This work aims to study the critical initiation conditions of a confined finite‐thickness explosive under jet impact and the influence of shell constraints on the explosive initiation threshold. A theoretical calculation model for jet impact initiation of a confined explosive is established based on the Pop plot of the explosive. A jet impact test is conducted on a confined TNT explosive covered by a 50SiMnVB cover plate by using Φ40 mm shaped charge. A high‐speed camera is utilized to record the reaction process of shelled explosives. Numerical simulation software is adopted to calculate the reaction process of the confined explosive under the jet impact, and the critical initiation threshold of the confined explosive is obtained. Experimental results are verified, and the propagation and development of bow shock in the confined explosives under different cover thicknesses are analyzed. Then, the calculation results of the theoretical model are compared with the experimental simulation results. The findings show that the critical cover thickness of the confined TNT with a thickness of 43 mm is 20 mm, and the critical initiation threshold is 31 mm 3 μs −2 . The theoretical model can accurately calculate the critical initiation threshold and change the law of explosives under unconfined and confined conditions. When the thickness of the explosive and the acoustic impedance of the shell material increase, the critical initiation threshold of the explosive decreases. The shell reduces the critical jet velocity for explosive initiation, and the influence of the shell on the critical jet velocity gradually decreases as the thickness of the explosive increases.