Influence of explosive type and constant γ in Mott’s stochastic model on terminal-ballistics parameters of high-explosive warheads using numerical simulations

Abstract

The research examined the use of numerical simulations for high-explosive (HE) munitions. Lagrange and Euler solvers from Ansys Autodyn, whose brief theoretical synopsis is given, were utilized. Numerical program modeling of materials under dynamic loads (explosives and solid bodies) is also explained. The study also provides a brief summary of relevant research works that address numerical simulations of the fragmentation of HE projectiles (warheads). First, using data from other authors, the numerical model in this paper was effectively validated. The original research in the publication included an evaluation of the influence of explosive type on mass distribution, as well as velocity and the kinetic energy of fragments on cylindrical warheads, along with some recommendations and findings. Results show that ordered by values of initial fragment velocity are explosives: Trinitrotoluen (TNT), H6, Comp. B, Octol, PBX-9404-3, and LX-10-1. Explosives LX-10-1 and PBX-9404-3 showed similar performance because both explosives are HMX-based mixtures, with LX-10-1 having 0.5% more Octogen (HMX). The greatest (fastest) expansion of fragments (for the given time frame of 150 µs) is present in the most potent explosives (LX-10-1 and PBX-9404-3) since they have the largest detonation velocities. In the configurations with stronger explosives (Octol, LX-10-1, PBX-9404-3), the front and rear cover of the cylinder is more fragmented than in the case of weaker explosives. The highest number of fragments is obtained with PBX-9404-3 explosive, 142% higher than using TNT charge. Also, as part of the original research in the paper, an assessment of the influence of the constant γ in Mott’s stochastic fragmentation model on the mass distribution of fragments and their kinetic energy was made. Results indicate that constant γ has the greatest influence on the number of very small fragments, which can be used when calibrating this constant with experimental data. The masses of fragments are relatively uniform (for all γ values) up to the mass group of 50–100 g, above which the most massive fragments are obtained when γ = 5. Most of the fragments have relatively high energy where that is, fragments of mass 0.5–2 g have an average kinetic energy of 470–650 J, while fragments of masses 50–100 g have an average kinetic energy of 50–85 kJ. Described numerical simulations are a valuable tool for HE warhead designers, as they can minimize the time and expense associated with optimizing HE munition design and effectiveness evaluation when used in conjunction with available analytical techniques and experimentation procedures.