A Quasi-3D Higher-Order Theory for Bending of FG Nanoplates Embedded in an Elastic Medium in a Thermal Environment

This paper presents the effects of temperature and the nonlocal coefficient on the bending response of functionally graded (FG) nanoplates embedded in an elastic foundation in a thermal environment. The effects of transverse normal strain, as well as transverse shear strains, are considered where the variation of the material properties of the FG nanoplate are considered only in thickness direction. Unlike other shear and deformations theories in which the number of unknown functions is five and more, the present work uses shear and deformations theory with only four unknown functions. The four-unknown normal and shear deformations model, associated with Eringen nonlocal elasticity theory, is used to derive the equations of equilibrium utilizing the principle of virtual displacements. The effects due to nonlocal coefficient, side-to-thickness ratio, aspect ratio, normal and shear deformations, thermal load and elastic foundation parameters, as well as the gradation in FG nanoplate bending, are investigated. In addition, for validation, the results obtained from the present work are compared to ones available in the literature.

Investigation of the microstructure evolution of 7CrMn2WMo economy‑alloyed steel in a new design forging tool implementing shear deformations

In this paper, a new forging technology realizing intense shear deformations during processing with a tool for its implementation was considered, and the influence of the proposed forging technology on the microstructure evolution of 7CrMn2WMo economy‑alloyed steel was revealed. A comparative analysis of the results of the microstructure evolution when forging blanks made of 7CrMn2WMo steel according to the proposed and current technologies proves the usefulness of a new design tool instead of the currently used flat strikers, since forging in the proposed forging tool provides more intensive and uniform processing of the cast structure over the entire section of the workpiece compared to forging in the flat strikers.

Stress–Strain Behaviour of Reparable Composite Panel with Step-Variable Thickness

There is an urgent problem of finding an economically viable method of maintenance and restoration of the bearing capacity of structures of various applications. Repair of structures with patches made of polymeric composite materials is one of the most promising repair technologies. However, an improper choice of parameters of the composite patch leads to unjustified increase in the structure mass and the cost of its further operation. These situations result from the lack of reliable methods for developing the repair process, which take into account the influence of the patch geometry and conditions for performance of repair works on the bearing capacity of the repaired structure. The mathematical model of the reparable composite shell–type panel taking into account inhomogeneity of transverse shear deformations at stepped variation of its thickness has been developed. In contrast to the classical theory of layered shells, the model allows simplifying a three-dimensional problem by setting of the displacement field on the layers’ interfaces and their linear interpolation over thickness of the panel, as well as considering the transverse shear deformations resulting from the strength, temperature, or shrinkage loading. According to results, the maximum rise in stresses in the case of a notched panel occurs in the weakened layer, and it is from this layer the failure of the structure will start. In the event of the patch, the panel surface opposite the reinforcement is the most loaded (i.e., susceptible to failure) surface. To confirm the reliability of the developed model, we compared the analytical calculations with the results of experimental and numerical studies of the deformed state of a panel of step–variable thickness by the method of holographic interferometry and modelling by the finite element method. Displacement fields available from experiments correspond to the predicted theoretical results. The resulting maximum error does not exceed 7%. The data obtained during numerical modelling allowed us to conclude that the accuracy of theoretical calculations is sufficient for engineering practice. Results of the work can be used to solve the practical problems such as determination of stress–strain behaviour of a damaged structure or structure after repair, specification of the permissible delamination dimensions, and defining of parameters of the bonded repair process.

Complex geodynamic indicators for forecasting hydrocarbon deposits in the arctic zone

In the article, in relation to the Arctic zone of the Russian Federation, a new method of forecasting hydrocarbon deposits based on computer geodynamic modelling procedures is considered. It is less expensive compared to field and analytical methods. The approbation of the method on the example of the Laptev Sea shelf zone showed a good interpretability of its results and their compliance with the forecast obtained by other methods. The rationality of using six geodynamic indicators for forecasting: the distributions of vortex structures of the velocity vectors of horizontal shear deformations and vortex structures of normal linear deformations; the values of the velocity vectors of horizontal shear deformations and velocity vectors of horizontal normal linear deformations; the distributions of the anomalous gravitational field in isostatic reduction and the reduced temperature. The sequence of stages in determining the potential of hydrocarbon deposits in the studied territories is described, which is associated with the solution of six interrelated sequential tasks: the choice of local territorial areas of optimal size - the calculation of geodynamic indicators – the allocation of homogeneous territorial clusters – the detailing and improvement of geodynamic indicators – the determination of the potential of oil and gas fields in the cluster – the localization of oil and gas fields in each cluster – construction of a digital forecast map of the location of oil and gas fields in the study area.

Gaivoron—Zavallia section of the Middle Pobuzhzhіa is the most representative part of the granulite complex of the Ukrainian Shield (structural-tectonophysical results and magnetometric studies)

In the article according to the geological and geophysical data of the well-exposed areas of development of Archean rocks of the Ukrainian Shield, two alternative approaches to establishing the structure and stratigraphy of the oldest granulite complexes are discuss. The outcrops of the enderbite-gneiss complex up to 3.6—3.8 billion years old are located along the Southern Bug River between the Gaivoron town and the Zavallia village. The first, «stratigenic-metamorphogenic» approach assumes that the main features of the composition and structure of the Lower Archean complexes are inherited from the original stratotypic strata. These strata are transformed in the conditions of quasi-isochemical metamorphism with preservation of the sequence of formation in section and the primary constitution in the form of stratification, rhythmicity, direction of change of their composition vertically and laterally. On the structural-formation map and geological section of the Gaivoron—Zavallia section, the Archean granulite complex is shown in the form of a synclinorium composed of four adjacent formations, which are equated to the world of metamorphosed volcanic-sedimentary rocks. The second, «deformation-metamorphogenic» approach, which is supported by the authors of this article, is based on the idea that the granulite complex of Pobuzhzhіa is a subvertically layered medium formed by tangential tectonic forces. The latter lead to shear deformations and displacement of matter at the atomic-molecular (with mineral transformation of rocks) and rock masses at the regional level. This creates structural and textural elements that are superimposed on the primary structure of rocks and often erase it. Field structural-tectonophysical, tectonofacial and magnetometric studies, its results are presented in the article. It was performed specifically to compare these two concepts. Magnetometric studies have shown that the enderbite-gneiss complex of the district by its magnetic characteristics belongs to the middle and lower crust of the Ukrainian Shield.

Parametric vibrations of piezoelectric viscoelastic cylindrical panels taking into account transverse shear deformations

The paper presents a numerical-analytical approach to solving problems of parametric vibrations of layered hinged piezoelectric viscoelastic cylindrical panels under electromechanical harmonic loading. The mathematical model is constructed using mechanical hypotheses about layer-by-layer approximation of shear deformations by quadratic functions on the thickness of panel, which are supplemented by adequate hypotheses on the distribution of electric field quantities when the components of the electric field strength vector and the normal component of the electric induction vector are different from zero. The dissipative properties of materials are taken into account on the basis of the theory of linear viscoelectric elasticity. To solve the problems, a technique based on the use of the variation principle and the representation of the required quantities in the form of decomposition into double trigonometric series has been developed. This makes it possible to reduce the considered problems to Mathieu-Hill-type equations taking into account energy dissipation, which are solved by the method of harmonic linearization, which allows to determine the boundaries of the regions of dynamic instability.

Adhesion Strength of Organic-Inorganic Terpolymers Containing Nanostructured Poly(Titanium Oxide) with Self-Cleaning Properties to Different Materials

Optically transparent organic-inorganic terpolymers based on poly (titanium oxide), hydroxyethyl methacrylate and organic monomers of the vinyl and (meth) acrylic series (acrylonitrile, butyl methacrylate, vinyl butyl ether, 2-ethylhexyl acrylate) were obained as a coating on silicate glass, polycarbonate, touch-up paint and metal. Materials’ light transmittance in the visible spectral range is 87 - 92% depending on the composition. The adhesion of terpolymers’ thin layers to substrates of various natures was investigated under shear deformations and by the lattice notch method according to ISO 15140. It was found that it is necessary to selectively excerpt composition of terpolymers in accordance with the nature of the substrate for creation adhesive durable coatings. The most durable coatings are formed on glass, polycarbonate and automotive enamel. It was revealed that the nature of the substrate and the composition of organic-inorganic terpolymers affect the hydrophobicity of the coatings and their ability to hydrophilize under the influence of UV-irradiation. The contact wetting angle of coatings with water, on average, reversibly varied within ~ 90 ° ↔ ~ 30 °.

Energy Analysis of Impact-Shear Interaction of Counter Flows of Ground Loose Material in Centrifugal Disintegrator

The distribution of power consumption of centrifugal two-shaft disintegrator for impact and shear destruction of material as functions of its technological and structural parameters, as well as parameters of material being ground, has been substantiated. An analytical apparatus has been developed to determine the degree of influence of each factor. Factors affecting the absolute value of the consumed power of the disintegrator have also been established. The results of the work make it possible to optimize the technological process in order to reduce the yield of bream fragments of destruction, which is observed when the share of energy of shear deformations increases, in order to obtain cuboid fractions of disintegration products. They allow to create a methodology for determining the rational parameters of a centrifugal double-shaft disintegrator.