Experiments of Initiation of Covered,but Unconfined High Explosive Charges by means of shaped charge jets

Experiments on the initiation of high explosive charges in contact with a barrier or separated from it by a 15 mm air gap or a 2 mm acrylic glass layer have been performed utilising a simultaneous framing and streak camera. With increasing barrier thickness the shaped charge jet is increasingly consumed.     

Experiments of Initiation of Covered,but Unconfined HE Charges under different test conditions by shaped charge jets

The initiation behavior of TNT/RDX 35/65 high explosive charges under the impact of the jet from a 44 mm diameter shaped charge with 7.8 mm/m̈s jet tip velocity, which has previously perforated a 100 mm thick barrier is reported. In these tests,

• the high explosive charge under test was divided into different sections by transverse air gaps, with the first section being in contact with the barrier, or
• the 100 mm thick barrier was sub-divided in such a way that one part of it was in contact with the high explosive charge under test, or
• various air gaps, ranging from 0.5 mm to 450 mm, were made between the acceptor charge and the barrier.

     

The importance of jet tip velocity for the performance of shaped charges against explosive reactive armor

It is shown, that the portion of a shaped charge jet that emerges from explosive reactive armor is longer or at least less disturbed if the jet tip velocity can be raised. Generally, the residual jet length largely depends on the ratio of the reaction time of the armor and the standoff of the shaped charge from the armor.     

Calculation of the critical detonation diameter of explosive charges using data on their shock-wave initiation

This paper deals with the further development of the quantitative theory of critical detonation diameter that was earlier proposed by the author. According to this theory, to calculate the critical diameter, it is necessary to know the shock adiabat, detonation velocity, and the generalized kinetic characteristic of decomposition of a high-explosive (HE) charge under shock-wave compression. It is suggested that the generalized kinetic characteristic of decomposition of a HE can be found from an experimental dependence of the shock-wave amplitude on the distance the shock wave travels during shock-wave initiation of the HE charge. This approach allows one to calculate the critical detonation diameters of HE charges with sufficient accuracy. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 112–115, March–April, 2006.     

Analysis of the shaped charge jet induced reaction of high explosives

A new optical recording technique for analyzing the initiation of high explosives under the impact of a shaped charge jet is described. This method permits determining, in “one single” test, the type of reaction – i.c. no reaction or reaction or detonation - and the parameters build-up distance Δs run-up time Δt, initiation time t_i and initiation distance Z_i in the acceptor charge by observation of the acceptor charge side-on and, via a mirror, also end-on with simultaneous streak and framing recording.     

Analysis of a shaped charge jet with the double-orthogonal-synchro-streak technique

Recording the trajectory of a fully-particulated shaped charge jet at two different positions along its flight path, in two mutually orthogonal planes at each recording station, allows the decomposition of the overall transverse velocities of the particles into two components. This can be done by analysing the differences in the deviations observed at the two stations. The overall transverse velocities are composed of the vector sums of those lateral- or off-axis velocities which are intrinsic to the collapse process, and additional increments that are superimposed later as a result of particulation itself. In this paper the “IEPG Shaped Charge” has been used as an example to demonstrate the Double-OSST measurement technique. In these experiments, the overall transverse velocities derived are clearly larger than those seen between the collapse line and the first observation station. On the “Z” diagram (dispersion to the charge axis), the measurements made on this shaped charge do not exhibit random radial dispersion in all direction, but rather the particles spread out into a fan which expands more or less within one quadrant.     

Wave processes in soils associated with the explosion of underground gas-jet shaped charges

Kiev. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 5, pp. 101–107, September–October, 1991.     

Relation between the critical detonation diameter of explosive charges with characteristics of their shock-wave sensitivity

Correlation dependences between the critical diameter of high explosive (HE) charges and characteristics of their shock-wave sensitivity are theoretically justified. Relations for the critical radius of curvature of the detonation-wave front and for the critical detonation diameter are derived on the basis of the author’s theory of the critical diameter and the generalized kinetic characteristic of HE decomposition determined from the experimental dependence of the distance of transition of the initiating shock wave to the detonation wave on the wave amplitude. A qualitative analysis of these relations reveals good agreement with available experimental data. Key words: detonation, critical diameter, sensitivity, shock-wave initiation of detonation, HE decomposition kinetics. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 3, pp. 101–105, May–June, 2009.     

An Analytical Model for the Particulation of a Jet from a shaped charge liner

A new model is presented to predict the cumulative breakup time of the jet from a shaped charge liner. The model invokes a plastic instability criterion, kinematic considerations, and a material constitutive equation. Very good agreement of the cumulative breakup time and jet length with experimental data for several copper liner geometries is shown. The results are dependent on the initial strain rate and jet temperature distribution.     

Formation of a high-velocity particle flow from shaped charges with a liner consisting of a hemisphere and a degressive-thickness cylinder

Particle flows formed from shaped charges with a combined steel liner consisting of a hemisphere and a cylinder with a hemispherical part of degressive thickness (decreasing from top to bottom) were investigated by flash radiography. It has been found experimentally that the change from a constant to a degressive thickness of the hemispherical part increases the velocity of the head part of the liner jet formed during its compression, which is subsequently separated upon collapse of the cylindrical part. The maximum particle velocity obtained as a result of separation in the experiments was 8.6 km/s.     

Analysis of Strains,Strain Rates and Temperatures during the early stages of shaped charge liner collapse

In trying to understand the extraordinarily high dynamic ductility of a copper shaped charge jet, prior work by the authors has utilized the Eulerian MESA 2D code with a novel form of the LaGrangean tracer particle technique as well as the experimental “soft recovery” and metallurgical examination of partially collapsed copper liners. This work had indicated that localized material processing occurs during the earliest stages of liner collapse and causes dramatic visible grain size refinement, evident in the photomicrographs. Further computational analysis shows that the localized plastic flow is accompanied by very high localized engineering strains (>200), extremely high (>4 × 10⁷ s⁻¹) localized strain rates, as well as elevated temperatures, all of which favor a dynamic recrystallization process. In this paper, the focus is on a detailed quantitative analysis of strain, strain rate and temperature distribution history within the collapsing liner, in the region of the inner liner apex and the early location of the moving collision zone, where the early material conditioning first occurs. Correlations are sought between the computed, time-dependent values of these three paremeters and the microstructures observed in the interiors of the partially collapsed liners, in those regions where the grain size changes are observed. This data may ultimately permit quantitative comparisons with the predictions of dynamic recrystallization models.