Measurement of Shock Initiation Threshold of HNAB by flyer plate impact

Abstract

The shock initiation threshold of HNAB (Hexanitroazobenzene) explosive has been measured using pressure pulses generated by flyer plate impact. The flyer plates were accelerated by an electrically exploded metallic foil (electric gun) up to velocity of 2.5 mm/m̈s generating impact pressures, P, up to 7.3 GPa lasting between τ = 40 ns to 210 ns, where τ is the duration of the impact. One dimensional semi‐empirical model was developed to describe the exploding foil process. We found a good agreement between the semi‐empirical model and the experimental data. It was found that as the pressure duration gets longer, the initiation threshold curve swings away from the P2τ= constant. For long (200 ns) pulses, the initiation criterion becomes one of a constant pressure. This constant threshold pressure is 2.9 GPa at 1.6 g/cm3 (grain size is 5 m̈m). The effect of the explosive density and grain size on initiation threshold can be explained by hot spots and porous explosive concept. A critical energy for initiation threshold of 12 J/cm2 was derived from our measurements (with flyer thickness 76 m̈m and grain size 5 m̈m).

Shock to Initiation Characters of Heated Explosives with Different Confinement

“…The shock initiation properties of explosives can be evaluated using tests such as the gap test, the wedge test, or the flyer plate test 6 that employs a gas gun or a standard donor explosive as the propelling device 7. Both gap test and wedge test require thermal insulation of the explosive test sample, which inevitably adds to the complexity of the experiment device, while the use of a gas gun necessitates the construction of a blast‐resistant target chamber that not only is costly, but also significantly limits the amount of sample that can be placed within.…”

The Initiation Threshold Sensitivity of HNS Explosive as a Function of its Grain Size

“…Die Ziindschwellenempfindlichkeit des Sprengstoffs HNS in Abhangigkeit von seiner KorngroBe Die Ziindschwellenempfindlichkeit von HNS wurde in Abhiingigkeit von der KorngroBe gemessen unter Venvendung einer elektrischen Kanone bei zwei Plattendicken. Die Ziindschwelle (kinetische Energie der Flugplatte) in Abhangigkeit von der KorngroRe zeigt, daR die Grenzwertkurve drarnatisch ansteigt bei einer KorngroRe groBer als 5,4 pm (bei einer Plattendicke von 76,2 prn und Sprengstoffdichte von 1,6 g/cm3). Die Mindestwerte fur die kritische Energie wurden berechnet zu 12,15 & 0,5 J/cm2 bei einer Plattendicke von 76,2 pm bzw.…”

“…I 1'arnorGage i i l'aide d'un canon Clectrique en utilisant deux diffkrentes Cpaisseurs de clinquant. L'tvolution du seuil d'amoqage (Cnergie cinktique de la plaque projetCe) en fonction de la granulomitrie montre que la sensibilite croit considCrablement, dks que la taille des grains dkpasse 5,4 pm (pour un clinquant de 76,2 pm d'Cpaisseur et une masse volumique de I'explosif de 1,6 g/ crn3). Les valeurs minimales pour I'Cnergie critique, fournies par le calcul, sont de 12,lS ?…”

Characteristics of a plasma flow field produced by a metal array bridge foil explosion

“…However, the shape and structure of the metal bridge foil are crucial factors that affect energy deposition and conversion efficiency. Currently, in most applications, the metal bridge foil connection area is generally a single bridge structure with an approximately square shape [2][3][4][5][6][7][8]. Many theoretical and experimental studies have been conducted on the influence of bridge material, size, and the corner shape of the bridge connection on the electrical explosion performance, and some valuable results have been obtained [9][10][11][12][13][14][15][16].…”