The natural modes and frequencies of an elastic ring fixed at a point are determined by numerically solving a boundary-value problem for a differential operator of the sixth order. The ring models a large circular antenna that slowly expands under zero gravity. The in-plane flexural vibrations of the ring are analyzed. Numerical results are presented

There are carried out a construction of a generalized mathematical model and a numerical modelling of the dynamics of a spacecraft with a carried body of changeable geometry. This model describes a deployment of a compact body in a ring antennae.

We analyze the problem of the stress distribution in an elastic orthotropic medium with an arbitrarily oriented elliptical crack. To construct the problem solution, the Willis approach is used which is based on the triple Fourier transformation of spatial variables and Fourier-image of Green’s function for an infinite anisotropic space. The investigation results in special cases are compared with the data of other authors. The effect of the elliptical crack orientation in an orthotropic space on the distribution of the stress intensity factors along its contour is studied.

We consider the inverse problem of thermoelasticity for an isotropic medium containing a cavity of unknown shape and subjected to the action of mechanical and thermal loads. Nonlinear equations are deduced for the geometric parameters of an ellipsoidal equistressed cavity. Similar relations for mechanical loads obtained by the other authors follow from the constructed equations as special cases. The numerical analysis is performed and the relationship between the values of the loads and the parameters of the cavity is investigated. The stresses on the equistressed surface of the cavity are found and the influence of temperature on the relationship between the parameters of loads and the geometric characteristics of the equistressed cavity is analyzed.

By solving the stationary thermoelastic problem for a transversally isotropic hyperboloid of revolution we conduct an analytic study of the thermal stress state of a finite solid of revolution with a meridional section of complicated shape and propose a way to solve the problem of the reliability of information obtained using the numerical methods developed and algorithms implemented on a computer.

The solution of the axisymmetric elasticity problem for an unparted hyperboloid of revolution is used to obtain the exact analytical solution of the reference problem of the thermally stressed state of an isotropic solid of revolution with finite dimensions and a transverse cross section of complex configuration.

Single crystals of La/sub 3/Ga/sub 5/SiO/sub 14/ (LGS, langasite) can act as laser media and are also highly effective piezoelectrics having zero temperature coefficient of frequency. We have grown large langasite single crystals, diameter up to 50 mm and mass up to 600 g, by a modified form of Czochralski's method with automatic control, where we found that the main inhomogeneities are bulk defects, which are localized in the axial section no matter what the orientation for the seed, and inclusions, which include bubbles and microcracks, transverse growth banding, and block structure. These inhomogeneities are related to the growth conditions and make themselves felt in different ways. The optical quality was evaluated from the anomalous birefringence.

Stainless steel powders produced by the calcium hydride process contain substantial amounts of hydrogen, nitrogen, and oxygen impurities. Sintering in a hydrogen atmosphere is accompanied by further impregnation with interstitial phases, as a result of which the structure of the materials shows signs of a brittle state. Vacuum sintering removes excess products, both those present in the starting powders and those forming in the course of sintering, through degassing. As a consequence of this refining action, the materials are in a tough state.