Numerical Simulation of Multiple Explosively Formed Projectile Warhead Forming Characteristics considering Various Materials

To study the influence of different liner structures and materials (copper, steel, and tungsten) on the forming characteristics of multiple explosively formed projectile (MEFP) with integrated liner and shell designs, three types of liners with different structures were designed. LS-DYNA was used for numerical simulation, and the results show that the thickness change at the center of the liner has no obvious influence on the shape of the explosively formed projectile (EFP). However, the curvature radius of the liner has a significant influence on the shape of the EFP. When the liner material is copper and the curvature radius of the liner is greater than 8 mm, the EFP shape approximates an ellipsoidal or hemispherical shape and the EFP forming speed is between 1900 m/s and 2400 m/s. When the material of the liner is steel or tungsten and the curvature radius of the liner is thicker than 8 mm, the liner is not able to form projectiles in the shape of a sphere, ellipsoid, or long rod. By comparing the forming speed from 1#EFP to 4#EFP, it can be said that MEFP with integrated liner and shell design displays a certain pressurization effect. Research results show that, for small-caliber MEFP warheads, subject to the size of the warhead, when the liner is steel or tungsten, the detonation energy generated by the limited charge does not result in the liner forming an effective EFP. However, when the liner material is selected as copper, the EFP forming shape and speed are more appropriate.

Estimating the consequences of an explosion on critical infrastructure

The study is an analysis estimating the threat arising from the detonation products of a condensed explosive on the physical environment. It presents an analysis of fundamental detonation properties such as detonation height and Mach wave formation, related to their loading effects on critical infrastructure. Analytical equations as well as modelling were investigated to predict the effects of explosive loading on surroundings and people. Comparisons were made between the results from calculations with those of the equations, based on approximated experimental data. It was concluded that when applying the JWL equation of state to the reaction products of TNT, good agreement was obtained between modeling and experimental results for the detonation energy derived with the aid of thermodynamic calculations.

Numerical simulation for determining detonation parameters of explosive substances using EXPLO5 thermo-chemical prediction software

The article presents the theoretical and practical research results regarding the development of the IT and methodological infrastructure for assessing the parameters which define explosive substances. The software us intended for estimating, based on the chemical composition of substances, parameters which define such substances (detonation velocity, detonation energy, detonation pressure etc.), as well as for determining the probability of explosion. EXPLO5 is a specialized software which allows to solve thermo-dynamic equations between different reaction products in order to determine the balance composition, having incorporated a filtering algorithm for estimating Jones-Wilkins-Lee (JWL) state equations coefficients which are used for calculating the detonation energy of explosives. For the proper performance of pilot tests of numerical simulations upon certain representative types of explosives (civil use explosives and double-use explosives: civil and military) there have been taken into account the special characteristics of EXPLO5 provided by the EOS BKW (BKW standard with set of BKWN constants and BKW EOS modified with the set of constants and volumes BKWN-M) and EXP-6 EOS function which is based more on theoretical concepts.

Theory of Mach reflection of detonation at glancing incidence

We present a theory for Mach reflection of a detonation undergoing glancing incidence reflection off of a rigid wall. Our focus is on condensed-phase explosives, which we describe with a constant adiabatic gamma equation of state and an irreversible and either state-independent or weakly state-dependent reaction rate. We consider two detonation models: (1) the instantaneous reaction heat-release Chapman–Jouguet (CJ) limit and (2) the spatially resolved reaction heat-release Zeldovich–von Neumann–Dø̈ring (ZND) limit, where here we only consider that a small fraction of the detonation energy release is spatially resolved (the SRHR limit). We observe a three-shock reflection in the CJ limit case, with a Mach shock that is curved. We develop an analytical expression for the triple-point track angle as a function of the angle of incidence. For the SRHR model, we observe a smooth lead shock, akin to von Neumann reflection, with no reflected shock in the reaction zone. Only at larger angles of incidence is a three-shock Mach reflection observed.

On firework blasts and qualitative parameter dependency

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given.

Design of Laser Ignition System for Ejection Life-Saving System

Now the ejection lifesaving equipment in aircraft depends on the mechanical transmission device to transmit the initial detonation energy,but the device is with many transmission links, high energy consumption, quick wear, high failure rate, and difficult to be detected, to improve the ejection lifesaving equipment performance, laser technology was used successfully to ejection lifesaving equipment, a new type of laser initiating system was designed, its structure ,detector and test method of the system are introduced. The laser energy of the system was transmitted conveniently, fficiently and the system is easy to be checked and maintained, thus which greatly improves safety and reliability of the ejection lifesaving equipment.