Том 52, № 2 (2017)

The problem of choosing the program regime of a cycle mechanism motion on the basis of complex estimates of its energy and dynamic parameters is solved. An optimization criterion is formed as a functional consisting of the introduced parameters, which are determined by solving some differential equations describing the mechanism motion. For a specific mechanism, an example of complex estimate of its efficiency is given. An application procedure for the proposed method is discussed.

We present an asymptotic derivation of the two-dimensional equations of equilibrium of a thin elastic inhomogeneous plate manufactured of an anisotropic material of general form with 21 moduli of elasticity. We also consider simplified models obtained under special assumptions on the moduli. We use test examples to illustrate the error estimate of the proposed model and discuss its scope. The model is compared with the classical Kirchhoff–Love and Timoshenko–Reissner models.

The contact problem of indentation of a pair of rigid punches with plane bases connected by an elastic beam into the boundary of an elastic half-plane is considered under the conditions of plane strain state. The external load is generated by lumped forces applied to the punches and a uniformly distributed normal load acting on the beam.

It is assumed that the contact between the punch and the elastic half-plane can be described by L. A. Galin’s statement, i.e., it is assumed that the adhesion acts in the interior part of each of the contact regions and the tangential stresses obeying the Coulomb law act on their boundaries.

With the symmetry taken into account, the problem is stated only for a single punch, and solving this problem is reduced to a system of four singular integral equations for the tangential and normal stresses in the adhesion region and the contact pressure in the sliding zones. The solution of the constitutive system together with three conditions of equilibrium of the system of punches connected by a beam is constructed by direct numerical integration by the method of mechanical quadratures.

As a result of the numerical analysis, the contact stress distribution functions were constructed and the values of the sliding zones and the punch rotation angle were determined for various values of the geometric, elastic, and force characteristics.

The computations of the internal friction background arising due to the hysteresis mechanism of dislocation mobility in metallic systems at low temperatures carried out by different model representations are presented. It is shown that the general background of internal friction contains not only the losses due to hysteresis mechanism of oscillatory motions but also the losses due to other mechanisms of the structure defect mobility.

A technique for determining the damping properties of a rigid isotropic material from the experimental data on the damping capacity of elongated cantilever-fixed test specimens due to the internal and external aerodynamic damping is proposed. The following two methods for eliminating the aerodynamic damping component are considered: the extrapolation of the data on the damping capacity of a series of test specimens of different widths to the point corresponding to the zero width and the theoretical-experimental approach. The damping properties of the material are determined by the vibration logarithmic decrement depending on the amplitude of the linear deformation. This dependence is represented by a power polynomial. The polynomial coefficients are determined from the minimum condition of the goal function for the positive logarithmic decrement of the material vibrations. These coefficients are sought at the reference point by repeatedly solving the direct problem of determining the damping capacity of the test specimen from the given damping properties of the material. An example is considered to illustrate the identification of the damping properties of steel St.3.

The influence of magnetic field on the generation of a localized wave in a nonlinearly elastic conducting medium is considered. The evolution equation for describing the wave beam propagation in the medium is derived. It is shown that the wave beam parameters depend on the value of the external magnetic field and on the field orientation in space.