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The features of the propagation of elastic longitudinal and rod waves in single crystal cylinders under shock loading against a rigid wall are shown. The finite element method in a three-dimensional formulation simulates the shock loading of cylindrical bodies with the same height for cases of different orientations of the single crystal symmetry axes relative to the cylinder symmetry axis. The shock loading of the cylinders against a rigid wall is modeled with the same initial velocity, which ensures elastic deformation of the cylinders. The materials of the cylinders are zinc single crystals characterized by auxeticity. It is shown that the values of the velocities of propagation of elastic waves in cylinders depend on the direction of propagation, the ratio of the height of the cylinder to the diameter, and also on the location of the ultrasonic wave receiver. [ABSTRACT FROM AUTHOR]

The paper presents the results of numerical calculations of dynamic loading of thin cylindrical targets with a ratio of cylinder heights to its diameter 1 : 1 and 5 : 1. The propagation of elastic waves in cylinders with different ratios of heights to the radius of the VZhM8 single-crystal nickel alloy with cubic symmetry of properties in order to determine the propagation velocities of rod waves in the [001], [011] and [111] directions was simulated in this paper. The problem of loading of a target from VZhM8 by a steel projectile with a starting velocity was carried out by the finite element method in a three-dimensional formulation. [ABSTRACT FROM AUTHOR]

The formation of a crack under shock loading in HCP single crystals in the (101̅0) plane is simulated in the work. The simulation was carried out using the finite element method in a three-dimensional statement using the example of a zinc single crystal. The mathematical model allows to take into account the anisotropy of elastoplastic properties, the anisotropy of the propagation velocities of longitudinal and bulk waves, auxeticity, and the anisotropic pressure caused by bulk deformation in HCP single crystals. The formation of a crack is modeled as the fusion of individual elements in which the limiting porosity in a single crystal is exceeded in tension. The results of a comparison of velocity profiles of the rear surfaces of targets from a zinc single crystal obtained in calculations and in natural experiments by other authors are presented. [ABSTRACT FROM AUTHOR]

The study represents the analysis of numerical simulation of the failure of aluminum targets made of highly porous or solid 2024 alloy under dynamic loading. The calculations employed the finite elements method in threedimensional formulation with the use of proprietary programs. The article presents the results of the numerical simulation of Taylor's test for the projectile made of highly porous aluminum 2024 alloy at the velocities of 75 to 175 m/s. These results are in a good agreement with the results of the experiments. The peculiarities of the destruction of highly porous aluminum targets are shown. [ABSTRACT FROM AUTHOR]

The paper provides a 3D finite element simulation of shock-loaded anisotropic single crystals on the example of a Zn plate under impact using a mathematical model, which allows for anisotropy in hydrostatic stress and wave velocities in elastic and plastic ranges. The simulation results agree with experimental data, showing the absence of shock wave splitting into an elastic precursor and a plastic wave in Zn single crystals impacted in the [0001] direction. It is assumed that the absence of an elastic precursor under impact loading of a zinc single crystal along the [0001] direction is determined by the anomalously large ratio of the c/a-axes and close values of the propagation velocities of longitudinal and bulk elastic waves. It is shown that an increase in only one elastic constant along the [0001] direction results in shock wave splitting into an elastic precursor and a shock wave of "plastic" compression. [ABSTRACT FROM AUTHOR]

This paper studies the processes of fracture of barriers using the fracture criterion, allowing for consideration of large anisotropy for ultimate values of total plastic strains in various symmetry axes of an anisotropic material in conditions of sign-variable strain. All calculations were performed using the finite-element method under conditions of dynamic loading in three-dimensional graphics with the use of original software. It was shown that when modeling processes of fracture in barriers made of anisotropic and isotropic materials the differences in size and localization of fracture zones increase with the increase in the initial speed of shock loading of barriers. [ABSTRACT FROM AUTHOR]

The failure criteria of anisotropic materials, the criteria being expressed via deformations, are rarely applied in practice, and are usually used for low-ductility materials. Another situation involves the simulation of failures in materials with the high anisotropy of mechanical properties and that suffer elastic-brittle fracture. For such materials the failure criteria are formulated using ultimate strains and strain tensor invariants. For simulating the fractures of materials that are characterized by the anisotropy of strength properties, the failure criteria are applied with the critical values of stresses and strains, as well as their intensities. Using the value of cumulative plastic strain as a failure criterion does reflect the anisotropy of elastic and plastic properties of a material, but it does not reflect that of the strength properties. The application of this method allows accounting the total plastic strain induced by tension and compression in the conditions of the wave strain of targets during their impact loading. [ABSTRACT FROM AUTHOR]