Detonation performance and specific impulse characteristics of a PETN-based ultra-thin sheet explosive

The sheet explosive loading technology is a crucial method for evaluating the dynamic response of the space structure under the X-ray radiation in laboratory. To achieve the ultra-low specific impulse explosive loading required for the structural assessment of new space vehicles, a sheet explosive has been developed, primarily composed of PETN as the main explosive and polymer rubber as the binder. The mass fraction of PETN is 90%–92%, the thickness range is 0.15–0.20 mm, the density range is 1.63–1.68 g/cm³, and the explosive velocity range is 7.44–7.71 km/s. To verify the high-impact initiation sensitivity of the sheet explosive, three rounds of verification experiments were designed based on the blast marketing method. In the experiment, the sheet explosive was directly applied to the effect plate or a certain air gap reserved between the sheet explosive and the effect plate. The detonation of the explosive was confirmed by examining the explosive marks left on the effect plate post-explosion. The experimental results show that the sheet explosive with a thickness of 0.15–0.50 mm can be reliably detonated by a mild detonating fuse with a charge line density of 0.2 g/m, and the explosive strips with a thickness of 0.20–0.50 mm can reliably transmit detonation. The specific impulse characteristics of the sheet explosives with different diameters and thicknesses were measured and studied by the impact pendulum measurement device. Combined with theoretical analysis, the specific impulse calculation model of the sheet explosive was used to perform polynomial fitting on the specific impulse direct measurement data of the sheet explosives with the thicknesses of 0.20, 0.30, 0.40 and 0.50 mm, respectively. The specific impulse values of sheet explosives with four thicknesses were linearly fitted. The results show that the specific impulse of the sheet explosive is proportional to the thickness and the ratio coefficient is 3 418.56 Pa·s/mm. The development of ultra-thin sheet explosive with a thickness of 0.2 mm and a specific impulse of about 680 Pa·s was successfully realized.