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The article is devoted to the formation of a spray cloud after the interaction of an ultrajet with an obstacle. Variants of different mutual arrangement of the ultrajet and the surface on which the impact occurs are considered. Evaluation of the effectiveness of the choice of angle is carried out by analyzing the values of the coverage area of the target with a spray, set at a fixed distance from the impact site. It is accepted that a large contact area of the spray with the target surface is the best possible result. The research was carried out within the framework of the RFBR grants 18-29-18081 and 19-38-90228\19, the grant of the President of the Russian Federation for state support of the leading scientific schools of the Russian Federation NSh-3778.2018.8 and grants from the Innovation Promotion Foundation under the UMNIK-18 program in accordance with contract No. 14727GU/2019 and No. 14549GU/2019.

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.

The procedures of the technical support of zootechnical and veterinary measures for beef cattle breeding were considered in the article.

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 expediency of improving the indicators of judgment assessments of individual breeding characteristics of the Hereford cattle breed is justified. The proposed method of selecting cows according to a complex evaluation indicator is based on the principle of a point assessment with the correction of the selection significance of the absolute value of some economically useful characteristics that are definitely related to the economy of animal breeding. At the same time, it is characterized by the Breeding Value Index (BVI), which allows you to complete a selection group of cows in breeding herd with breeding value from 70 points and above. The main values of constructed index must select or create such genotypes that would combine the most important and desirable combinations of breeding traits. The method is universal for cows of different breeds, types, herds, provides breeding and formation of more highly productive and technological animals on the basis of meat productivity.

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.

The article discusses the features of mathematical modeling of technologies using high-speed water jet (for cutting, piercing, cleaning, including their use in the underwater conditions), as well as features of material destruction under water jet treatment. The physical-mathematical model of the process based on the use of the proposed equations of hydroabrasive suspension state and criteria-based dependencies describing the regularities of the processed material destruction was developed on the example of numerical solving two-dimensional axisymmetric problem of piercing holes in the structures of various materials by hydroabrasive waterjet. The features of the solid material destruction during the formation of a through hole in it under the action of a high-speed water jet are shown. Recommendations on choosing kinematic parameters of the cutting jet for different types of waterjet/hydrodynamic machining are given.

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...

This paper deals with specifics of mathematical modelling of machining processes using high-speed hydro-abrasive water jet (for cutting, piercing, cleaning) including the case of underwater application. We provide a numerical solution of the two-dimensional axis-symmetrical problem of hole piercing in structures from various materials and propose a mathematical model of this process. The mathematical model is based on the proposed equations of hydro-abrasive suspension state equations and criteria relationships describing the laws of material erosion for the given machined material.

The physicomathematical problem of the explosive formation of a cumulative knife (jet) from a cumulative charge and its penetration into a 250-mm-thick armed concrete obstacle is considered. Numerical simulation data for a specific extended cumulative charge acting against this obstacle at different focal lengths of the charge are presented.

The article considers a possibility to use the ultrajet diagnostics methods for definition of ceramics operational characteristics at the stage of production. The ultrajet technology means a complex of processing methods or research of constructional materials, which are subjected to the high-speed compact stream of liquid. In particular, the article considers the test method of the constructional ceramics used as a means of an armored protection, which means the influence of an water ultrajet flowing out at high speed (800 m/s) from a nozzle with a diameter of 0,1 mm. By quantity of the ceramics, which has been taken away from a zone of ultrajet influence, the article draws conclusion concerning the operational properties of a studied sample of ceramics. Apart from a widely used method of ceramics shooting, this way allows us to obtain information on a studied armor without using special equipment (the ballistic stand). However, the goal of the offered way is to obtain information on operational characteristics of a sample at the stage of production, the subsequent tests using shooting thus are not excluded.The possibility to use the ultrajet diagnostics methods as an addition to shooting is revealed from results of the experiments made with samples of ceramics after three types of tests such as shooting using a rigid drummer, ultrajet impact on a sample (including that of with using abrasive particles available in liquid), and static loading tests of samples. By results of each type of tests the misrostructure analysis of demolition zone of samples was carried out. The analysis has shown a similarity of a microstructure of dynamic influence zone on the samples subjected to shooting by the rigid drummer and an ultrajet (including that of with available abrasive particles). Thus, at static tests the demolition zone was essentially different in microstructure from the samples under dynamic trials. So, the conclusion was drawn that the ultrajet diagnostics method is admissible for use in retrieving more information about a sample at the stage of production.

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.

The possibility of increasing the intensity of a magnetic field produced previously in a conducting medium moving under the action of a high-velocity penetrating body is analyzed. A simplified model of the interaction of an impactor and a conducting target with a transverse magnetic field is constructed within the framework of a one-dimensional scheme. It is shown that the degree of increase in the field intensity is determined by the relation between the magnetic-field compressibility and diffusion factors, and the corresponding dimensionless determining parameters is determined. Magnetic-field compression is estimated for a perfectly conducting medium and media with real conductivity. The significance of the thermal and mechanical effects accompanying the penetration of an impactor into a target with a transverse magnetic field is assessed.