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A method for constructing nonstationary vibration equations for electro-viscoelastic composite plates with their active damping is described. The problem is solved in an integral Fourier transform frequency space. To construct a multilayer plate model, a discrete structural approach was used, i.e., the plate is divided through the thickness into computational layers, within which the displacements and electric potentials are approximated by means of quadratic Lagrange polynomials. At the edges of the plate, the Navier conditions are met. The semi-analytical nonstationary vibration equations are derived by means of the variational convolutional Lagrange equation. To represent them in a frequency space, a direct integral Fourier transform is used, which makes it possible to use experimentally determined frequency-dependent complex characteristics directly in calculations of nonstationary vibrations of plates without additional transformations of integral physical relations. Solutions of the problem of active damping of nonstationary vibrations for the frequency images of displacements and electric potentials have been found, their convergence is analyzed. The procedure has been evaluated by analyzing the active damping of nonstationary vibrations of a three-layer edge-hinged square plate under the action of a blast wave impulse. The middle layer is made of a composite material, and the outer electro-viscoelastic layers act as a sensor and an actuator. The active damping of vibrations is provided by connecting these layers of the plate into a negative feedback circuit with the proportional-differential control law. The viscoelastic and electro-viscoelastic characteristics of the materials are taken into account by means of complex elastic, dielectric and piezoelectric moduli. The results of analyzing the active damping of nonstationary vibrations of a plate are presented. The values of the proportional and differential components of the controller as characteristics of this damping were chosen taking into account the permissible electric field strength of the actuator. The research results for the case of passive damping of vibrations are also given for comparison. The dependences of the decrement of plate vibrations on the differential component of the controller and of the maximum plate deflection on the reinforcement angle of the middle layer material have been established. The optimum reinforcement angle according to the minimum plate deflection criterion has been determined, which provides an increase in the efficiency of active damping of nonstationary vibrations of the plate owing to an increase in the differential component of the controller.

The authors present the results of the numerical experiments on the determination of the effect of shrouding coupling parameters in the rotor blades on their forced vibrations using an assembly of two blades as an example. The task is solved in the variation of the inclination angle of the shrouded flanges as the parameter of their contact interaction and amplitude of the kinematic excitation of vibrations caused by the harmonic displacement of the root section of the assembly. The displacement amplitude in the plane of the assembly vibrations and stress intensity in the blade airfoil is accepted as the characteristic of the forced blade vibrations. The finite element models of the blade assembly, which are based on the linear 8- and 4-nodal contact finite elements, are used to perform the investigation. The authors have obtained the dependencies of the selected characteristics of forced vibrations within the blade airfoil on the inclination angle of the contact surfaces of their shrouded flanges to the plane of rotation of the rotor wheel and level of kinematic excitation of the assembly vibrations. It is implied that the variation in the angle has a considerable effect on the stress state in the blades under investigation and it results in the occurrence of the local minimum of their forced vibration characteristics. Here the increase in the amplitude of the kinematic displacement of the root section in the assembly causes the increase of rigidity of the shrouded blade coupling and reduction in the triggered energy scatter.

The paper presents the results of the computational experiments to determine the regularities in the variation of the static stress state characteristics of blades as a function of the inclination angle value of the shroud contact surfaces relative to the plane of rotor wheel rotation with a consideration of the action of centrifugal gravity forces and high temperatures of the gas flow.

The complex procedure of multicriterial optimization of cylindrical shells with the layers from fiber-reinforced viscoelastic composite materials is presented.

The test data for ring specimens from heat exchanger tubes without defects are compared to those for specimens with various types of defects. A relation between strength characteristics of the specimens and the nature and depth of defects has been clarified.

An efficient method for the analysis of nonstationary vibrations of structures by finite element modeling in the space of Fourier transforms is presented.

The effect of damping on nonstationary vibrations of elements of manipulators and mechanisms with flexible links is considered. To analyze nonstationary vibrations in the case of kinematic excitation, a finite-element frequency method was employed, which is based on numerical integral Fourier transformation.

A method of determination of the limiting pressure for gas and oil pipelines susceptible to local corrosion is discussed. The proposed method is based on a combined use of strength criteria of the continuum mechanics and fracture mechanics. Its applicability is verified by the results of numerical studies and laboratory model tests.

We analyze the applicability of the methods of the theory of nonlinear programming to the development of the optimal design of laminated plates with maximum damping.

Causes of fracture of the martensitic-ferritic steel blades of the variable inlet guide vane for an axial-flow compressor of the gas pumping unit GTK-25I have been studied. There are several stages of blade fracture: corrosion, fatigue, and fracture. At the initial state, corrosion damage occurs at the martensite-ferrite interface, which is followed by intragranular corrosion damage along martensite needles and fatigue failure within the grain bodies.

The paper considers a technique for the optimal design of structures made of viscoelastic materials with the purpose of reducing vibration amplitudes at dynamic loads.

The variational formulation of a problem is frequently used in strength analysis of parts and structural elements. The authors present a variational principle whose Euler's equations are the differential equations of thermoelasticity for stresses.

We analyze the most common procedures of tensile testing of circular specimens applied in different institutions of the former USSR and compare the characteristics of the plasticity of circular specimens made of zirconium alloys obtained by different methods. This enables us to conclude that the procedures of tensile testing of circular specimens should be unified and standardized.

Stress concentration factors are presented for a turbine journal tip loaded with centrifugal forces and turning moment. The space elasticity method is used for the investigations.