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The effect of the velocity of compact metal projectiles of spherical and cylindrical shapes on the size of craters formed in steel targets of different strength was studied in the velocity range 2–10 km/s by numerical simulation using two different computational techniques. The behavior of the materials of the projectile and target is described using a model of a compressible elastoplastic medium with a constant yield strength. The projectile materials are copper, titanium, and tantalum. The projectile mass and velocity are specified assuming that their kinetic energy is constant. It is found that the dependences of the crater depth on the velocity of projectiles with constant kinetic energy have a maximum and the crater volume decreases monotonically with increasing velocity.

A single-phase physico-mathematical model of a high-speed waterjet forming process that uses the underwater abrasive waterjet cutting technology while an abrasive-liquid flow under a pressure ranging from 60 to 80 MPa passes through the jet-forming path of a mobile abrasive waterjet machine has been developed. The results of a numerical experiment are presented. It has been shown that the main structural parameters of the internal profile of the jet-forming element (the profile of the focusing cavity, diameter and length of the output-channel) influence the geometric and kinematic parameters of the formed jet and the consumption of the hydro-abrasive suspension.

For testing anti-meteoroidal protection of spacecraft, it is proposed to use charges that form compact elemants of variable shape. Shape charges, their construction, and the process of functioning are considered. During the operation of such a charge, the explosive throws the metal liner at a distance of several hundred charge diameters. The metal liner is deformed in motion and takes a compact shape. In this case, copper liner of variable thickness were used, the outer and inner surfaces of which are formed by a combination of spherical surfaces. A plane-wave generator with a variable angle of inclination of the detonation wave is considered as an initiation system in the charge. The results of mathematical modeling of the functioning of charges, which determines the effect of charge parameters on the effectiveness of the action, are presented. The efficiency of the charges was determined by the parameters of the compact element - its shape and speed. The paper also evaluated the influence of the angle of inclination of the plane-wave generator on the shape of the element. The dependences of the speed of the element and its elongation on the angle of inclination of the converging detonation wave are obtained. It was found that when the angle of inclination of the converging detonation wave front decreases, the elongation and speed of the compact element increase.

The results of mathematical modeling of the process of forming elongated element from segment charge liners for testing anti-meteoroid protection of spacecraft using numerical methods of continuum mechanics are considered. The paper presents options for improving such charges to increase their effectiveness. Data from computational experiments with various structural parameters of steel segment liners are described. In models with different physical and mechanical properties of the facings, the mechanism of forming an elongated element from the liners with a gradient in the radial direction of plasticity is demonstrated. It is shown that the control of physical and mechanical properties in the liners makes it possible to form filled and aerodynamically stable element. The application of the elastic-plastic deformation model and the fracture criterion in the form of the Smirnov-Alyaev criterion is justified.

The paper introduces the results of numerical simulation of the functioning of shaped charges, whose liners are made of different materials. As a result of their functioning, these charges form high-speed elements. Typically, liners for such charges are produced by the cold stamping technology. An alternative method for producing the liners is metal spinning. Moreover, a spin formed liner is expected to have higher physical and mechanical properties compared to a stamped liner made of the same material and having the same geometrical parameters. To reveal the patterns of molding high-speed elements from stamped and spin formed liners, the action of shaped charges comprised of steel or copper segmental liners of small bending, was simulated numerically using the apparatus of continuum mechanics. The influence of the liner manufacture method was taken into account by varying the values of the physical and mechanical characteristics of the liner material. The design parameters of the simulated charge, with the exception of the liner bending, during the calculation study remained unchanged and corresponded to the parameters of the currently used samples. Following the numerical experiments results, the study shows that the elements molded from spin formed liners are less likely to become fractured while being formed and are also more integral (continuous) in comparison to the elements molded from stamped shaped charge liners.

The paper considers the possibility of using compact projectiles formed by an explosion to break through strong steel barriers of finite thickness protected by a layer of water. There is no problem in penetrating such barriers by high-gradient and high-speed shaped-charge jet of a small diameter formed by shaped charges with ‘high’ conical liners, however, the diameter of the through hole formed in the steel barrier is fairly small and does not meet the defeat criteria for corresponding barriers. To increase the diameter of a through hole in a steel barrier, shaped charges with ‘low’ conical or flat hemispherical liners (in the form of a meniscus) forming compact projectiles can be used, but the movement of such ‘shock cores’ in the water layer is sharply slowed down, up to a complete stop even before interacting with the main steel barrier. The purpose of the paper is to substantiate the possibilities of eliminating this disadvantage when using compact projectiles. Based on theoretical and experimental studies, the paper offers a technical solution related to the known fact of the formation of a cavern (gas cavity) during the movement of a shaped-charge jet in water, expanding as the jet penetrates in the radial direction. In this case, if a known tandem scheme of shaped charges placed one after the other along the axis of the explosive device is used, the first shaped charge, often called pre-charge, will penetrate the body in the head part of the explosive device to the water layer, then form in the latter a cavern up to the main penetrable barrier and the second shaped charge, often referred to as the primary, will form a compact projectile moving to penetrable barrier in the cavity formed by the penetration of shaped-precharge jet in the water. At the same time, due to selecting the necessary delay time between the pre-charge and main charge explosions as well as the design parameters of the pre-charge, the size of the expanding cavity must exceed the size of the compact projectile, excluding its interaction with water up to the approach to the penetrable steel barrier.

In this paper, we present the results of numerical simulation of explosive formation of a high-speed compact element from copper, steel, and aluminum cumulative liners combining the shape of a hemispherical segment smoothly converting into a cylindrical surface (“hemisphere–cylinder” liners). The problem is solved in a two-dimensional axisymmetric setting considering the limiting parameters of the dynamic stress-strain state causing plastic flow and destruction of the cumulative liner material. The original model of the functioning of cumulative shaped charge, which determines the effect of individual elements of the cumulative liners, including the difference in numerical characteristics of their physicomechanical properties and critical destruction conditions, on the final parameters of the high-speed compact element, was used. The plastic properties of the material and the critical conditions for its destruction were found not to affect the final velocity of the formed high-speed compact element, but they affect its shape, dimensions, and mass.

We substantiate the recommendations for improving the efficiency of hydro- and hydroabrasive cutting of the honeycomb structures that are widely used in aircraft and rockets, obtained by numerical solving of the spatial dynamic problem with allowance for the physico-mechanical and kinematic parameters of a high-speed jet, the physico-mechanical and structural parameters of the treated honeycomb structure, and the parameters of the technological treatment (feeding and the impact angle of the jet with the face surface of the blanks). A physico-mathematical model and a method of numerical analysis of the process have been developed. The influence of the above parameters on the quality of the surfaces of the treated blanks is illustrated. The results of the calculations are compared with the experimental data.

The study proposes to use charges forming high-speed elongated elements (HSEE) with a variable shape for ground-based simulation of the penetration of particles and elements into the spacecraft's hull. During the operation of such a charge, an explosive throws a metal lining over a distance of several hundred charge diameters. The metal segment lining is deformed during the throwing process and takes the form of an elongated element. In calculations we used steel linings with a degressive and progressive profile whose outer and inner surfaces are formed by spherical surfaces, as well as by a combination of spherical and conical surfaces. The paper shows the results of a numerical analysis which determines the effect of the geometric and physico-mechanical parameters of segmented cumulative linings on the efficiency of the charges forming high-speed elongated elements. The efficiency of the charges was determined by the characteristics of the formed element, i.e. elongation, degree of fullness and the diameter of the horizontal stabilizer. Furthermore, we established the dependences which describe the effect of the lining material dynamic yield point and the radius of transition of the spherical surface to the conical surface on the elongation of the element and the diameter of the horizontal stabilizer. We also showed the possible contradictory effect of changing the radius of transition of the spherical surface of the lining into the conical surface on the aerodynamic stability parameters of the high-speed elongated element.

We consider the physicomathematical formulation of the problem of explosive formation of a penetrator from a low-sphericity copper lining. Calculations are made for the formation of a penetrator for a phlegmatized hexogen charge for two models of the behavior of the lining material (copper), and the results are compared with the experimental data.

For ground-based simulation of the penetration of particles and elements into the body of the spacecraft, it is proposed to use charges that form high-speed elongated aircraft (HSEA) with a variable form. In the course of the operation of such a charge, an explosive agent throws a metal liner for a distance of several hundred charge diameters. The metal segment liner is deformed in the process of throwing and takes the shape of an elongated aircraft. Steel cladding with a degressive and progressive profile was used, the outer and inner surfaces of which are formed by spherical surfaces, as well as a combination of spherical and conical surfaces. The results of the numerical analysis, which determines the influence of the geometrical and physicomechanical parameters of segment cumulative liners (CL), on the effectiveness of the action of the charges that form high-speed elongated aircrafts are presented. The effectiveness of the charges was determined by the characteristics of the formed aircraft — elongation, degree of fullness, and diameter of the tail plane (skirt). Dependencies describing the influence of the of the liner material and the radius of transition of a spherical surface into a conical surface on the elongation of the aircraft and the diameter of the skirt are established. The possible contradictory effect of a transition in the radius of transition of a spherical liners surface into a conical surface on the parameters of the aerodynamic stability of a high-speed elongated aircraft is shown.For ground-based simulation of the penetration of particles and elements into the body of the spacecraft, it is proposed to use charges that form high-speed elongated aircraft (HSEA) with a variable form. In the course of the operation of such a charge, an explosive agent throws a metal liner for a distance of several hundred charge diameters. The metal segment liner is deformed in the process of throwing and takes the shape of an elongated aircraft. Steel cladding with a degressive and progressive profile was used, the outer and inner surfaces of which are formed by spherical surfaces, as well as a combination of spherical and conical surfaces. The results of the numerical analysis, which determines the influence of the geometrical and physicomechanical parameters of segment cumulative liners (CL), on the effectiveness of the action of the charges that form high-speed elongated aircrafts are presented. The effectiveness of the charges was determined by the characteristics of the formed aircraft — elongat...

The shock stage in the behavior of explosively loaded steel plates and cylindrical shells was studied experimentally. A three-wave structure of the shock front was observed for both plane and cylindrical samples. The split-off strength of the shell and plate materials was determined. For both loading schemes, the split-off was shown to not occur for the samples with a thickness of 1 mm. The decay of the pressure amplitude in the first shock wave was found to be appreciably stronger for the cylindrical samples than for the plane samples.

The equation of state was developed for materials subjected to the polymorphic transformation upon explosive loading with an explosive charge. The formula obtained was used in the numerical modeling of the explosive projection of plates and cylindrical shells fabricated from St 20 steel. The theoretically estimated kinematic parameters of a projected body were compared with the experimental data.

The effect of preheating of liners on the penetration capability of shaped charges is considered theoretically. It is shown that for a plastically fractured shaped‐charge jet, preheating of the liner generally increases the effective jet length and shaped‐charge jet penetration. Restrictions on the parameters of preheating of shaped‐charge liners due to the possible thermal initiation of the explosive are established. It is noted that excessive weakening of a shaped‐charge jet can lead to transition from plastic to volume fracture with a corresponding decrease in shaped‐charge jet penetration. The ultimate possibilities of the thermal method for increasing the penetration capability of shaped charges are estimated. Calculation results are compared with available experimental data.