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Optical methods for recording fast processes are applied to study a flow behind a detonation wave front in a nitromethane/polymethyl methacrylate (NM/PMMA) mixture. It is shown that, an increase in the PMMA concentration leads to an increase in the critical detonation diameter, which, as in pure NM, is determined by the occurrence of reaction failure waves at the charge-shell boundary. A NANOGATE-22/16 high-speed eight-channel sixteen-frame electron-optical camera is used not only to properly study the spatial occurrence and propagation of reaction failure waves, but also to determine their characteristic size. It is shown that unstable flow at the edge of the charge in the NM/PMMA mixture can be stabilized by adding amines or glass microspheres.

Based on model experiments, approaches to numerical modeling of detonation wave propagation in small-section channels filled with PETN-based explosive (pentaerythritol tetranitrate) are investigated with account for macroscopic detonation kinetics.

This paper describes the process of obtaining homogeneous mixtures of RDX, HMX, PETN, TNT, Fox-7, and benzotrifuroxane of various dispersions with polysiloxane (SKT) as an inert soft polymer. The specific surface area of crystalline explosives (HE) varies from 440 to 4750 cm²/g, and the explosive content in the mixtures ranges from 65 to 82% (wt.). Each binary mixture (explosives/polysiloxane) yields solid, practically nonporous, flat (round ones with a diameter of 40 mm and square ones with a size of 40 × 40 mm) charges of various thicknesses and elongated cylindrical (cord) charges of various diameters. Flat and cord charges are characterized by the same composition, dispersion, density, and defectiveness of explosive crystals. Critical thicknesses and critical diameters of detonation of all mixtures are determined experimentally with an accuracy of 0.05 mm. Test conditions: flat and cord charges without shells located on a metal base. It is revealed that the ratio of the critical diameter to the critical thickness of detonation is practically constant and equal to 1.83 ± 0.1. The previously obtained dependence of the critical detonation diameter of explosives and explosive mixtures on the change porosity is also taken into account. An equation for the correct recalculation of the experimental critical detonation thickness of pressed charges of crystalline explosives with real porosity into the critical detonation diameter of high-density charges is obtained. This equation is additionally confirmed by testing many individual explosives of different dispersion and known literature data conducted in this work.

This paper presents thermodynamic calculations of characteristics of explosive mixtures based on tetramethylammonium perchlorate. Their sensitivity, explosion heat, and volume are determined. The composition of gaseous explosion products is analyzed. This paper also demonstrates the possibility of creating promising explosive mixtures with detonation ability and mechanical sensitivity in the TNT-RDX range, with an explosion heat of higher than 6 MJ/kg and a hydrogen content of gaseous explosion products of more than 50% by volume.

This paper presents the results of a study of explosive compositions with the replacement of the combustible filler-aluminum powder-by an aluminum- and boron-containing composite mixture prepared by mechanical activation. Thermodynamic calculations of the characteristics of fillers and explosive compositions were made using the TERRA software and the NIST database. The compatibility of fillers with active binders and the influence of fillers on the detonation characteristics, blast and propulsive effects, and brisance of model explosive compositions were studied.

Response of materials to pulse loading by cylindrical specimens is determined via two interrelated processes: shock wave motion toward the sample axis and perturbation motion in the form of triple shock configurations along the shock wave front. The surface area of the perturbed shock wave front increases due to protrusions strengthened as a result of merging with shock-wave-generated smaller perturbations. Because the front area sharply increases as the shock wave approaches the axis, several large triple shock configurations are formed and the shock wave front is divided into separate sectors in which they oscillate. The collision of powerful shock structures ensures the shock wave front motion toward the axis by removing a portion of the compressed material from the collision zone forward ahead the shock wave front and the additional compaction of the shock-compressed material by longitudinal shock structures under the wave front. The cumulation process is completed when the height of the protrusions becomes equal to the distance from the shock wave front to the axis. The near-axis space is occupied by the front protrusions, and the resulting reflected shock wave slows down the oncoming flow.

The convergence of cylindrical copper shells subjected to explosion has been investigated. The shell surface was covered with an explosive layer. Explosion was initiated at eight points evenly spaced on a cylindrical surface. During the convergence, eight ejections were formed on the inner surface the shells; i.e., buckling of the smooth deformation front occurred. The formation of ejections is attributed to the occurrence of plastic (cumulative) jets during the interaction of adjacent shock and deformation waves. The structural mechanism of convergence of thick-walled copper shell consists of the formation, expansion, and closure of ejections. It has been found that the formation of ejections is preceded by another buckling mechanism of the deformation front-corrugation.

This paper presents the results of a study of hydrodynamic instability during the collapse of shells, in particular, shaped charge liners. Initially, this instability was initiated by harmonic surface perturbations or perturbations of the load parameters. The instability manifested itself in the form of the development of these perturbations over time. The absence or limited growth of surface perturbations was considered as a manifestation of the stability of the liner deformation process. In this study, we take into account the results of both numerical simulation and available experimental data. Based on the results of the study, conclusions are formulated about the causes and possible forms of manifestation of instability during the deformation of collapsing metal liners, the governing parameters of this process, and its features and mechanism.

The present paper describes an X-ray experiment on explosive compression of spherical shells made of boron carbide and lead with single-point initiation of detonation on the surface of a spherical explosive layer. Experimental data are compared with numerical modeling results using the LEGAK technique. There is satisfactory agreement in the type of failure of boron carbide shells in the calculation and experiment.

The brightness and color temperatures of shock-heated fused silica were determined at thermal radiation wavelengths of ~390 to 630 nm using a four-channel pyrometer. The measurements were carried at shock compression pressures of 27.6-50.5 GPa. It is shown that the emission spectrum of shock-heated fused silica is a superposition of the thermal emission spectrum and the line spectrum. Baric dependences of the emissivity and absorption coefficient of shock-compressed fused silica were determined.