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The effect of a hole radius in an elastic layer on a critical external load at the moment of the onset of fracture, determined by the energy criterion, is investigated. Using the free energy flow through an interaction arc as a fracture criterion makes it possible to describe the dependence of the critical external load on the hole radius. The length of the interaction arc constructed in the vicinity of a free energy peak point is determined using a linear parameter. The introduced linear parameter for a polymethyl methacrylate layer is obtained using known experimental data. The maximum value of the linear parameter can be taken as a material constant.

Based on the Timoshenko beam theory, the vibration properties of a bidirectional functionally graded carbon nanotube reinforced composite beam are investigated. The governing equation of free vibration for the composite beam is derived, which considers the main influential factors, such as the gradient index and the distribution, aspect ratio, and volume ratio of carbon nanotubes. The differential quadrature method is used to solve the governing equation. The natural frequency of the composite beam is obtained. It is found that the natural frequency and vibration mode shapes of the beam are dependent upon the gradient index, nanotube distribution, and volume ratio of nanotubes. However, it should be pointed out that the nanotube distribution in the height direction and the volume ratio of nanotubes have very limited effects on the mode shapes of the composite beam.

In order to study the hardening that occurs during the application of coatings obtained by spraying powder material, experiments were carried out on glass shot blasting of steel test strips using a CCDS2000 detonation complex. Experimental dependences of the cold hardening depth δ and the magnitude of residual stresses σ in the hardened layer on processing parameters (size, density and velocity of particles, strength of the test strip material) were obtained. Engineering formulas are proposed for calculating the values of δ and σ.

A model is proposed for assessing the durability of a bundle of identical fibers under conditions of brittle fracture in the region of tensile stresses located to the left of the Griffiths fracture threshold. It is shown that in the specified stress range, the average durability and the dispersion of durability values increase indefinitely with decreasing tensile stress. Estimates were obtained for the incubation period of durability, its confidence probability and the lower limit of the number of elements of a bundle of identical fibers that guarantee the required durability of the bundle.

Two models are considered, which describe the equilibrium state between an inhomogeneous two-dimensional body with two connected rigid inclusions. The first model corresponds to an elastic body with three-dimensional rigid inclusions located in regions with a constant width (curvilinear rectangle and trapezoid). The second model involves thin inclusions described by curves. In both models, it is assumed that there is a crack described by the same curve on the interface between the elastic matrix and rigid inclusions. The crack boundaries are subjected to a one-sided condition of non-penetration. The dependence of the solutions of equilibrium problems on the width of three-dimensional inclusions is studied. It is shown that the solutions of equilibrium problems in the presence of three-dimensional inclusions in a strong topology are reduced to the solutions of problems for thin inclusions with the width parameter tending to zero.

Using metallographic and ultrasonic pulse-echo methods, studies of the destruction process of St3sp steel under uniaxial tension and fatigue were carried out. Samples were cut from the welded joint, namely from the zone of the base metal and the area of incomplete recrystallization in the heat-affected zone. A comparative analysis of the evolution of rough slip bands in the heat-affected zone and in the base metal was carried out. A connection has been established between the Poisson's ratio, determined by the ultrasonic method, and the mechanical characteristics of the material. Methods have been proposed for estimating the plasticity life under uniaxial tension and the number of cycles before failure due to fatigue.

This paper presents a solution to the Gadolin problem of the evolution of stressed states during the shrink-fit assembly of two cylindrical pipes. The materials of the assembly parts are described using the mathematical model of an ideal elastic-viscoplastic material. The friction law is specified on the contact surface of the materials of the assembly. The yield criterion is taken to be the condition of maximum octahedral stresses (Mises condition) in which the yield stress depends significantly on local temperature. Calculations of time-varying thermal stresses are performed in successive time steps, depending on the temperature distribution reached by that time. The results of calculations of the residual stress and fit interference in the assembly are compared with the values obtained from a numerical-analytical solution of the one-dimensional problem. It is noted that the calculations neglecting the singularity in the boundary conditions predict the different behavior of the fit interference in the near-end region of the structure.

The capsule review of the scientific editor for the thematic issue of the Siberian Journal of Forest Science, 2023, number 5 is presented, dedicated to the studies in dendrological parks and botanical gardens.

The competent organization and safety of the public space of the city, the educational and educational potential of its territories underlie the implementation of infrastructure and environmental projects. Despite the fact that every year we hear in the news about the planting of several thousand trees in the landscaping of the city of Krasnoyarsk, the total area of green zones and the provision in terms of a person remains insufficient. Requires the preservation of existing and the creation of new recreational areas. From the point of view of territorial connectivity, the presence of several types of landscapes, the diversity of vegetation, objects of scientific, historical and spiritual development, the project of forming a new cultural, educational, educational and scientific space of the city in the area of Akademgorodok, on the territory of the arboretum of V. N. Sukachev Institute Forest Siberian Branch, Russian Academy of Sciences, Church of the New Martyrs and Confessors of Russia, «Krasivy Bereg», «Gremyachaya Griva». The scientific and educational foundation of this project can be the arboretum of V. N. Sukachev Institute Forest Siberian Branch, Russian Academy of Sciences. This requires the preservation and restoration of its territory within the boundaries of the growth of introduced trees and shrubs, the development of the Regulations on the Arboretum as a specially protected object of nature, the implementation of infrastructure, environmental and educational projects.

During the field experiments on artificial inoculation, the mycelium of Grosmannia aoshimae (Ohtaka et Masuya) Masuya et Yamaoka fungus was observed to spread slowly in the conductive tissues of Siberian fir ( Abies sibirica Ledeb.) trees that retained their viability after slow intensity attack by four-eyed fir bark beetles ( Polygraphus proximus Blandford). In damaged trees the length of phloem necrosis after artificial inoculation of trunks with G. aoshimae culture was approximately 30 % less than in trees without signs of attack. The most likely reason for the inhibition is the defense reactions presumably induced in stems by unsuccessful attempts of the beetle attack prior to artificial inoculation. This phenomenon raises the question of the lack of knowledge about induced resistance in coniferous species. In contrast to herbaceous plants induced resistance in woody species including coniferous ones has been poorly studied. It was demonstrated that natural or artificial “low-intensity” infection with pathogens can increase tree resistance to diseases in branches and trunks, as well as to stem pests. However, the signaling pathways that cause the activation of defense reactions have not yet been sufficiently characterized. Because of the size of woody plants and the multiplicity of their ecological relationships, it is of particularly importance to study the interactions between molecular signaling pathways that are running from the different sites of damage. Studies of induced resistance in conifers, especially the characterization of endogenous signaling pathways, open the new prospects for tree conditions diagnosing, developing environmentally friendly methods for regulating the resistance of forest stands, mitigating the pest impact on trees, including the cases of biological invasions.