Vol 63, No 4 (2018)

A technique for calculating the backscattering of ultrashort pulses of plane waves by an ideally conducting cylinder is described on the basis of the spectral representation. The Rayleigh solution in the Bessel function series representation is used to determine the scattering spectral components. The Gabor impulse reflection is investigated. A method for remote determination of the cylinder diameter from the shift of scattered field amplitude peaks is described.

The algorithms of investigation and processing of results are described. The results of investigations of the vibration effect on corrosion wear of steel samples in an aqueous medium are presented. Cases of horizontal and vertical arrangement of samples are considered. It is noted that the samples subjected to vibration are affected by greater corrosion wear in an aqueous medium.

The effect of stress pulses on the formation of an intermediate layer in freshwater ice under an impact and in the ice bulk at a shear under conditions of quasi-static compression is considered when applying finite-amplitude elastic waves and when the fronts of these waves collapse.

The images of Vickers indentations in titanium are obtained by photoacoustic microscopy with piezoelectric-signal detection. It is shown that the analysis of the photoacoustic-image features makes it possible to obtain information on the nature of internal stresses in metal. In the framework of the single-temperature model of material thermoelasticity, it is demonstrated that the detected changes in the structure of photoacoustic images may be caused by the dependence of the thermal-expansion coefficient on stresses and by the presence of stress concentrators within the indentation.

The semi-inverse solutions of pure beam bending problems within the three-dimensional formulation of gradient elasticity theory as exact tests for the problem of estimating the efficient bending stiffness of so-called scale-dependent thin beams and plates due to the necessity of modeling sensing devices are presented. It is shown that the solutions within the gradient elasticity theory give classic beam bending stiffnesses and demonstrate the invalidity of the widespread results and estimates obtained in the past 15 years during study of scale effects within the gradient beam theories, according to which the relative bending stiffness grows by a hyperbolic law with decreasing thickness.

Analytical expressions for the impedance characteristics inherent to an optimum absorber are derived. The results of the laboratory experiment in which the simplest optimum absorber is constructed and investigated are presented, and the validity of the analytical relations obtained is confirmed.