Fragment Velocity Distribution of Cylindrical Rings Under Eccentric Point Initiation

Abstract

A design mode, in which a casing is filled with a charge initiated off‐centre (eccentric point initiation), is common in the field of explosion and structural protection. The fragment velocity distribution along the circumference of the casing is distinctly non‐uniform due to the difference in blast loading around the circumference of the casing. To quantify the fragment velocity distribution, two kinds of cylindrical rings with different structural parameters were adopted. Static explosive experiments with three eccentric coefficients (0, 0.5, 1.0) were conducted with pulsed X‐ray diagnostics. Using coefficients derived from experimental data and calculating the effects of both the eccentricity of initiation and angle around the circumference, an angle‐dependent ratio βθ of charge mass to casing mass has been derived as a mean to modify the fragment velocity formula of Gurney for this application. The derived formula was shown to correctly predict the fragment velocity distribution around the circumference of the cylindrical ring. The calculated velocity distributions show good agreement with the experimental results.

New Formula for Fragment Velocity in the Aiming Direction of an Asymmetrically Initiated Warhead

“…In calculating the velocity in the aiming direction (q ¼ 0 ), f ðqÞ ¼ 2, as if twice the charge/casing mass ratio is used in the Gurney formula. However, one problem of Held's formula is that when q ¼ 180 the velocity result is 0, which is not in accordance with experimental results [6].…”

“…Under constraints on warhead weight and volume, enhancing fragment velocities could increase the utilization of explosive energy and improve the probability of damage to targets. A simple way to increase fragment velocities is applying asymmetrical initiation, which increases fragment velocities in the opposite direction of the initiation points (the aiming direction) [4][5][6][7]. Those fragments in the aiming direction are intended to hit targets during the projectile-target encounter.…”

“…Huang [6] researched the velocity distribution of cylinder rings under eccentric point initiation. This research considered not only the eccentric point initiation but also the different positions of the eccentric initiator with a parameter of eccentric ratio a (although usually a equals 1, that is, initiator locates at the interface of the charge and the casing).…”

Rapid assessment of the spatial distribution of fragments about the D-shaped structure

“…The spatial distribution and velocity of fragments are two most important parameters of deformable warhead, which determine the damage area and damage degree of the target, respectively. It has been reported in the literature [17][18][19][20][21][22] the experimental and theoretical research on fragment dispersion and velocity distribution about the fragment generators. The theoretical velocity of fragments can be quickly estimated by Gurney formula.…”

Research into the Energy Output of Asymmetric Cylindrical Structure under Internal Explosion Loading

“…Lian et al [3] utilized the MPM (material point method) to simulate the explosively driven metal problems, and a new correction function to the Gurney solution was put forward, which considered the lateral effects for the flat sandwich configuration. Huang et al [4] and Wang et al [5] have all researched the fragment velocity distribution of cylindrical casings under eccentric point initiation. The explosive experiments were conducted with pulsed X-ray diagnostics, and the formula derived from experimental data can achieve fast computation of fragment velocity distributions.…”