Shock Initiation Of Solid Explosives Research Articles

Prediction of Initial Temperature Effects on Shock Initiation of Solid Explosives by Using Mesoscopic Reaction Rate Model

Abstract A kind of mesoscopic reaction rate model is reexamined in this paper with the aim of getting rid of the temperature dependence of its experiential parameters and making it available to predict the shock initiation of solid explosives under different initial temperatures. It is found that the initial temperature effect is induced mainly by the temperature dependence of the local chemical reaction rate and the initial density of the explosives, and, via the introduction of such temperature dependence, the reaction rate model can predict well the shock initiation processes under different initial temperatures, in which just the experiential parameters under a certain temperature (e.g. the normal temperature) are needed. Moreover, for verification, the shock initiation processes of PBX-9501 under different initial temperatures were simulated numerically by using the DYNA2D software. The numerical results on the run distance to detonation are found to be in good agreement with previous experimental data.

Shock Initiation of Energetic Materials at Different Initial Temperatures (Review)

Shock initiation is one of the most important properties of energetic materials, which must transition to detonation exactly as intended when intentionally shocked and not detonate when accidentally shocked. The development of Manganin pressure gauges that are placed inside the explosive charge and record the buildup of pressure upon shock impact has greatly increased the knowledge of these reactive flows. This experimental data, together with similar data from electromagnetic particle velocity gauges, has allowed us to formulate the Ignition and Growth model of shock initiation and detonation in hydrodynamic computer codes for predictions of shock initiation scenarios that cannot be tested experimentally. An important problem in shock initiation of solid explosives is the change in sensitivity that occurs upon heating (or cooling). Experimental Manganin pressure gauge records and the corresponding Ignition and Growth model calculations are presented for two solid explosives, LX-17 [92.5% triaminotrinitrobenzene (TATB) with 7.5% Kel-F binder] and LX-04 [85% octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX) with 15% Viton binder] at several initial temperatures.

A mechanistic model for shock initiation of solid explosives

This paper is devoted to the building of a model for the ignition and growth of a detonation in pressed solid explosives. The ignition model describes the various phenomena occurring at the microscopic scale during viscoplastic pore collapse. The growth stage is represented by a model combining inner combustion inside the pores and outer combustion on the surface of the grains. These microscopic models are incorporated into a macroscopic one. The macroscopic model reproduces waves propagation and takes into account the various couplings between the microscopic and macroscopic scales. Pores and grain size distributions are also considered. The governing equations are solved using a shock tracking high resolution scheme, in order to avoid numerical smearing of the shock front. The role of microscopic topology of the explosive is investigated. Results are validated on pressure gauge records and shock to detonation transition distance (Pop-plots).

Detonation Initiated by High-Pressure Gas Loading of a Solid Explosive

A one-dimensional numerical treatment reproduces experimental trends observed in the shock initiation of solid explosives; it has consequently been used to show that a rapid gas loading of a solid explosive to the initiating pressure for its charge configuration effects detonation. The deflagration-to-detonation experiments (pressure generated by confined burning of cast explosives) and air-gap sensitivity tests (pressure generated by gaseous detonation products of an explosive donor) are examples of detonation caused by gas loading.

Shock Initiation of Solid Explosives

Initiation phenomena in solid explosives produced by strong shock waves are described. Shock pressures in the explosive are between 20 and 200 kbar. It is demonstrated that in the usual case the shock wave travels not as an inert shock, but as a shock to which the explosive contributes energy, probably from reaction at voids and defects. This slightly reacting shock travels at increasing velocity for some distance, typically 1 cm in the experiments described, and then in a travel of perhaps 0.01 cm becomes full detonation, moving at full velocity. The increase to full detonation velocity occurs without overshoot. Experiments demonstrating the variation of sensitivity to shock with density, grain size, and other properties are discussed. The explosives studied are cyclotol B, TNT, plastic-bonded HMX, and nitromethane-carborundum mixtures.