Embedded Manganin Gauge Measurements and Modeling of Shock Initiation in HMX‐Based PBX Explosives with Different Particle Sizes and Porosities

Abstract

A series of shock initiation experiments on the explosive PBXC03 (87 % HMX, 7 % TATB, and 6 % Viton by weight) with different particle sizes and porosities under various shock loadings have been performed, and it is found that the particle size and the porosity of the explosives have much influence on the shock initiation characteristics. That is, the smaller the particle size, the more difficult the explosive to be ignited but the faster the detonation grows once the explosive is ignited. It is also found that the detonation grows the fastest in the explosive with moderate porosity. Moreover, a modified mesoscopic reaction rate model based on the experimental results and the pore collapse hot-spot ignition mechanism is developed, which allows for a separate reaction mechanism evaluation at different reaction stages for the shock initiation and detonation growth processes in the explosives. The calculated pressure-time histories and Pop-Plots for PBXC03 are founded to be all in good agreement with the experimental data. The modified mesoscopic reaction rate model shows its potentiality for quantitatively predicting the effects of the mesostructure of PBXs on the shock initiation and detonation growth processes with a high degree of confidence.Keywords: Shock initiation · Lagrangian experimental system · Modified mesoscopic reaction rate model · Particle size · Porosity · PBX explosive Embedded Manganin Gauge Measurements and Modeling of Shock Initiation in HMX-Based PBX Explosives Propellants Explos. Pyrotech. 2020, 45, 908-920 www.pep.wiley-vch.de

A Statistical Hot Spot Reaction Rate Model for Shock Initiation of Polymer‐Bonded Explosives

“…Finally, the reaction rate and reaction degree of ignition per unit volume of explosive can be obtained as, (18) (19) Therefore, the thermodynamic parameters to be determined in the hot-spot ignition term are T 1 , b, γ, v 0 , A, P*, and P c .…”

“…A multitude of studies showed that pore collapse is a dominant hot-spot mechanism for shock initiation of pressed solid explosives [6,[11][12]. Recently, Duan et al [12,[15][16][17][18][19] proposed an elastic/viscoplastic pore collapse "hot-spot" model and then developed a Duan-Zhang-Kim (DZK) mesoscopic reaction rate model, which can well delineate the effects of initial temperature, loading pressure, particle size, porosity, and binder's content/strength on shock initiation and detonation growth of PBXs. Up to now, the DZK model is generally accepted due to the advantage that fewer parameters in the DZK model need to be determined compared with the most commonly used ignition and growth model (IG) developed by Lee and Tarver [20].…”

Research on Detonation Growth Characteristics of the Cast CL-20

“…Lagrangian gauge measuring methods are used to study the detonation growth, which can accurately test the pressure histories during the shock initiation of explosives so as to study the influence of loading conditions, material properties, microstructures, etc. The commonly used Lagrangian gauge measuring methods contain manganin piezoresistive pressure gauge measurement [1][2]and electromagnetic particle velocity gauge measurement [3][4].…”

Experimental Study of the Crystal Habit of High Explosive Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in Acetone and Dimethyl Sulfoxide

“…EMs with needle morphology or sharp edges are more sensitive to mechanical stimuli, while a spherical morphology can contribute to decreasing the mechanical sensitivity. , For example, the impact sensitivity ( H 50 ) of hexanitrohexaazaisowurtzitane (HNIW or CL-20), one of the most powerful explosives, decreased from 25.5, 36.4, 41.8, to 52.6 cm, as its morphology was changed from dipyramid, cuboid, cubic, to spherical . Crystal morphology is also a critical factor in the formulation of plastic bonded explosives (PBXs), as it directly influences the adsorption properties of a binder at the crystal/polymer interface and consequently the mechanical property and detonation performance. , Theoretical calculation indicates that the (020) surface plane of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and (010) surface plane of 1,1-diamino-2,2-dinitroethylene (FOX-7) have the largest binding energies and therefore the strongest ability to interact with the hydroxyl-terminated polybutadiene (HTPB) binder . For octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) which was extensively applied in plastic bonded explosives (PBX) and solid rocket propellant, , the polarity difference between the crystal faces leads to the change of adhesion interaction between HMX and the Estane binder, and hence affects the mechanical property of HMX-based PBX .…”