Vol 45, No 1 (2016)

The key stages of the development of generalized dynamic theories of bending oscillations of rods, plates, and shells, based on the shear model proposed in 1921 by S.P. Timoshenko, an outstanding Ukrainian scientist, are considered. The mathematical construction of equations of the theory of plates obtained as hyperbolic approximations of the elastodynamics problem for a layer are presented and the analytical expression for the shear coefficient is derived. Some relevant current studies are mentioned. The propagation of waves along an elastically fixed strip is studied as an example.

Problems were considered concerning energy consumption decrease in spring drives, with the use of nonlinear spring accumulators provided by guides, unloading at mid position, depending on the carriage mass with a working body. The value of the axis offset of the spring fixation providing the lack of loading on the guide along its entire length was determined. Potentials of the drive self-locking in extreme positions without driven fixing rods were shown. Friction losses in the elements of the nonlinear spring accumulator were determined. A fivefold decrease of the dissipation losses for optimum size of accumulator as against the linear spring accumulator was shown.

We consider the spectral characteristics of rope vibroisolators. In rope vibroisolators, the vibration energy is absorbed at the expense of the dry friction between the separate elastic wires in the strands of the steel rope system. We have performed experiments in conditions fully identical to those in the hydro-support tests performed earlier [1]. We have found that, under the equality of the spectral constituents of the input vibrosignals, the spectra of the output signals of the rope vibroisolators differ sufficiently from the output signals of the hydro-supports obtained earlier [2–4].

The results of an experimental–theoretical investigation of high-cycle fatigue of a VZh-159 alloy at a temperature of 850°C are represented. A model and algorithm for the prediction of fatigue damages are proposed, which, with respect to relationships of damaged-medium mechanics, permit the simulation of processes of high-cycle structural failure subject to general factors affecting the cyclic strength of structural material. The results of the numerical simulation of high-cycle failure of structural elements are given that verify the working capacity of the proposed model, algorithms, and software environment developed based on it.

An automated technique for the technological process reliability evaluation is supplemented with an improvement stage to provide the quality of complexly shaped machine elements manufactured by the sheet stamping. As a result, there is a possibility to expediently develop and realize measures for the structural improvement of an element manufactured by stamping in cases using CAE software, when technological process correction does not provide conditions for defectfree stamping.

The exact analytical solution of the nonstationary heat conduction problem with a nonlinear internal heat source at the nonsymmetric third-type boundary conditions was obtained by the method of variable separation. The relations between the boundary condition parameters and a heat source separating the stationary processes from processes of an unlimited temperature increase (thermal explosion) were found. For known physical properties of medium, the maximum allowable value of the specific power of a heat source has been found. If nonsymmetric boundary conditions are exceeded on wall surfaces, it can lead to thermal destruction.

In calculations of the hard deformed state of rotation shells, the problem of incompatibility of triangular sampling elements with respect to derivatives of components of displacement vectors arises. In order to eliminate this weak point, it is proposed to adjust Lagrange multipliers in combination with an invariant vector procedure of approximation of displacement fields.

This work is devoted to the specific features of the rolling of hollow shafts made of nickel-base superalloys under conditions of superplasticity. Limitations are mentioned, which hamper the use of the highly efficient multiroller rolling of the shafts made of these alloys under conditions of superplasticity. The tried and tested procedure of rolling hollow shafts, which involves the use of a mandrel and a single roller, is presented. It is shown that the shaping of a shaft using this procedure requires an expanded bulk deformation zone to appear, which propagates over the entire cross section of the blank under the zone of its contact with the roller. The dimensions of the tool that provide the formation of this deformation zone are determined. The possibility of the use of the axisymmetric formulation of the problem on bulk deformation in the course of the rolling of shafts to determine the stress-strain state of the material is substantiated with the help of the Deform-3D applied software package.

The aim of this work is to determine the possibility of using EI893 alloy to produce rotor blades of the first stage of the GTE-45-3 gas-turbine power plant.