The authors investigate aluminum shaped charge jet (SCJ) penetration into an aluminum alloy target at 8–11 km/s velocities. The analysis of kinetics, penetration parameters and structures of cavern ...surfaces formed after the penetration show that at velocities exceeding 9–11 km/s, the hydrodynamic character of the penetration changes due to the melting of the interacting materials. When during the penetration process SCJ velocity exceed 9 km/s, porous layer of aluminum nanospheres with 20–100 nm in diameter form in the penetration region. The results obtained are appropriate for developing spacecraft shield protections against most dangerous space fragments.
•Hydrodynamic penetration of shaped charge jet changes due to the melting.•Melting destabilizes penetration at velocities over 9 km/s.•Porous layer of nanospheres forms on the cavern walls.•Number of nanospheres decreases with increasing penetration depth.
Parameters of an elongated hyper-velocity projectile formed by a detonation of a cumulative charge are determined. The projectile's mass, impact velocity and energy were determined. Penetration ...pressures are calculated by the deceleration method. Values obtained are compared with commonly known data on phase states of interacting materials – melting and partial evaporation. An elongated projectile penetration through a screen protection into a target is analyzed. Experimental data obtained reveals high efficiency of a screen protection against an elongated hypervelocity projectile in an area of interacting materials evaporation.
•Copper elongated projectiles with mass 0.25g and velocity 7.4km/s were used.•Cu, steel, and Al double layer shields with the same area density were compared.•Copper shield causes 32% reduction of penetration inside the Al target.•When steel shield was used, the reduction is 17% and in the case of Al shield – 5%.
Aircraft safety and security is a very important problem of nowadays. Terrorist bomb attacks on transport are most dangerous and often result in numerous victims. Threat of terrorist attacks on air ...transport is a nagging problem. The goal of the present paper is to present results of developing efficient air bomb inhibitors that preserve aircraft safety in case of onboard detonation of explosive equal of 2kg TNT.
Methods for protection developed within the present paper could be successfully used for developing effective and lightweight shield for a spacecraft against high velocity impact of space debris fragments, which could also induce blast loads.
•An efficient air bomb inhibitor was developed preserving aircraft in case of onboard detonation of explosive up to 2kg TNT.•Theoretical analysis made it possible to suggest effective and light-weighted shielding material.•Experimental investigations and field tests testified its effectiveness.•On-board experiments were performed successfully.
This paper introduces a new method using jet-charges for testing shields developed for spacecraft protection against micrometeoroids and man-made debris. A test pattern for obtaining a gradient-free, ...explosively formed jet is considered. Values of the high-speed projectile velocity, mass and energy are assessed in relation to the angle of the conical liner and the angle of the high-explosive detonation front. Maximum parameters of the high-velocity projectile have been found, and the range of the practical interest has been determined.
•A new method using jet-charges for testing spacecraft protection shields is developed.•A test facility for obtaining a gradient-free, explosively formed jet is considered.•Values of the high-speed projectile velocity, mass and energy are assessed.•Maximum parameters of the high-velocity projectile have been found and confirmed experimentally.
Relation between blast wave parameters resulted from a condensed high explosive (HE) charge detonation and a surrounding gas (air) pressure has been studied. Blast wave pressure and impulse ...differences at compression and rarefaction phases, which traditionally determine damage explosive effect, has been analyzed. An initial pressure effect on a post-explosion quasi-static component of the blast load has been investigated. The analysis is based on empirical relations between blast parameters and non-dimensional similarity criteria. The results can be directly applied to flying vehicle (aircraft or spacecraft) blast safety analysis.
•An efficient method to suppress HE effects onboard a flying vehicle was invented.•Corresponding protective device was developed and tested.•The results of tests at normal pressure onboard are valid also at diminished one.
The problems involved in the design-engineering digital simulation of large-size transformable-screen constructions for protecting spacecraft and equipment from space debris and meteoroids were ...considered. The engineering principles used to improve the design and efficiency of protective screens are presented. The use of embedded matrix transducers located all over the composite material used for armor tiles is proposed for the construction of protective clad screens; this approach enables efficient detection of damaged areas of the protective screen, the assessment of the level of damage, and the prediction of damage to spacecraft and equipment structures.
•Innovative spacecraft protective unit was developed.•Principles for guidance and control of rotating shield segments were developed.•Effectiveness of different control strategies was evaluated.•Digital simulators of the innovative design-engineering solutions were developed.
The overpressure and impulse of the compression phase transmitted to a rigid wall through the layer of dispersed material during the propagation of a spherical shock wave along it are determined in ...experiments using a conical shock tube. The layers of sand of different fineness and thickness are investigated by varying the intensity of the shock wave. The conditions under which the shock wave’s amplitude increases are revealed. The impulse of the compression phase of the shock wave transmitted through the bulk medium weakly depends on the layer thickness and the intensity of the shock wave.
The use of high-modulus ceramic materials under conditions simulating the screen protection of space objects from damage by fragments of space man-made debris is considered. The introduction of an ...aluminum jet at a speed of ~ 10 km/s into an aluminum barrier located behind brittle material screens was experimentally studied. A comparative analysis of the parameters of the residual cavity in the barrier made it possible to reveal the effect of the structural rearrangement of the ceramic material on the effectiveness of screen protection.
The droplet epitaxy of indium on the As-stabilized GaAs(001) surface is investigated using theoretical model and experimental studies. The model is developed on the basis of a combination of the ...nucleation thermodynamic theory and kinetic Monte Carlo algorithm. The surface density of droplets is observed to decrease with increasing temperature whereas both the droplet diameter and height increases because of the intensive attachment of In adatoms to larger, i.e. more stable, islands. At the same time, the droplet aspect ratio demonstrates a nonmonotonic temperature dependence. Although a general tendency for the aspect ratio with increasing temperature is falling, there is a temperature at which the aspect ratio is maximal both for simulations and experiments. This is caused by the temperature balancing between the wetting of the substrate and the formation of islands with near-spherical shape. The simulation results are in good agreement with obtained experimental data in a wide range of substrate temperatures.
The article presents the results of experimental studies of the regimes of formation of self-organizing In/AlGaAs nanostructures by the method of droplet epitaxy under As-stabilization conditions at ...different Al content in the surface layer. Dependences of the influence of the growth temperature, surface composition, and deposition thickness on the geometric characteristics of the In nanodroplet arrays such as density, size and dispersion. The possibility of controlling the parameters of nanostructures array by changing the Al content in the surface layer. An unusual dynamics of the change in the critical thickness of the formation of In nanodroplers is revealed with a change in the composition of the surface.
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