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The determination of the elastic wave propagation velocity using ultrasonic methods for a calculation of the elastic constants imposes constraints on the geometry of bodies. The paper studies the compressional wave propagation in an aluminum cylinder after a collision with a rigid wall and in cylinders made of anisotropic single-crystal zinc with different crystallographic orientation of a single crystal relative to the cylinder axis of symmetry. The initial energy separation from the repulsion energy of cylinders, secondary repulsion energy of cylinder parts from the rigid wall, and elastic strain energy of repulsed cylinders made of isotropic and anisotropic materials are described for single-crystal zinc. The different geometry boundaries are found for the bodies to study the elastic wave propagation with a view to identify the elastic constants. [ABSTRACT FROM AUTHOR]

Nickel titanium single crystal is used to show the importance of the volume compressibility anisotropy in analyzing the elastoplastic deformation processes in metal single crystals with the cubic symmetry. The process of uniform bulk deformation corresponds to the process of nonuniform stress-strain state of metal single crystals of cubic symmetry for several orientations of the theoretical coordinate system relative to crystallographic directions of the main axes. The indicative surface of the volume compressibility (or its reciprocal variable of bulk modulus) has an aspherical shape and is the function of the Euler angles. This is shown for the first time based on the solution of the model problem, viz. determination of the stress-strain state of a spherical body made of nickel titanium single crystal during the transmission of a compressive pulse through the tested material. In general case of orientation of the theoretical coordinate system relative to main crystallographic axes, a spherical body made of nickel titanium single crystal undergoes deformation due to the compressive load and acquires the shape of a two-axial ellipsoid. [ABSTRACT FROM AUTHOR]

The results of a numerical study in a three-dimensional formulation of the processes of elastoplastic deformation of a cubic single crystal based on the Ni3 Al intermetallic (VZHM8) under impact loading are presented. Impact loading is carried out in the [001] direction. The development of deformation processes is studied in the [100] and [010] or [011] and [011] directions. In the former case, the crystallographic directions of the single crystal coincide with the axes of the computational coordinate system and the elastic constants in these directions are the same. In the latter case, only one axis coincides with the [100] crystallographic direction, the other two are rotated by an angle of 45°. It is shown that a change in the elastic constants of a single crystal in new directions results in a change in the volume compressibility in all three directions. This is a consequence of the generalized Hooke's law. In the mathematical model used in this work to describe elastoplastic deformation, it is assumed that the volume compressibility of the single crystal is constant in the region of elastic and plastic deformations. It is shown for the first time that with the above rotation of the coordinate axes in a cubic single crystal, a change in elastoplastic deformations in the direction of the axis of impact loading is observed. [ABSTRACT FROM AUTHOR]