Mechanism and suppression of the effect of axial rarefaction waves on the eccentric initiation effect

Abstract Eccentric initiation is an innovative design for warheads, by which warheads are detonated off-axis. The effects of eccentric initiation have been well studied. However, it has been found that the experimental and numerical results of the circumferential distribution of fragment velocity under eccentric initiation are inconsistent, yet no rational explanation has been reported. In the present work, the influence of axial rarefaction waves on the eccentric effect was numerically studied as a major factor for such an inconsistency. The circumferential fragment velocity distributions of the cylindrical casings filled with explosives with different length-diameter ratios ( L / D ) under eccentric initiation were numerically studied. The results indicate that axial rarefaction waves affect the acceleration process of fragments, and subsequently influence the effect of eccentric initiation. The axial fragment velocity distributions of the casings with different numbers of end caps were measured with X-ray radiography to explore the axial rarefaction wave suppressing performance of end caps. The experimental results indicate that end caps can significantly suppress the effects of axial rarefaction waves. Our work has provided a scientific foundation for the studies on eccentric initiation and engineering design of innovative warheads.