Calculation of tectonic stresses in the earth’s crust of SouthWestern Uzbekistan

In this article, based on accounting, the interaction of the Earth’s crust blocks is limited by the deep breaks in the form of three-layer panels. The analysis dependences for tectonic pressure on elasticity parameters and the Earth’s crust layers capacity were obtained using the hypothesis of linear changes of deformations on the height of panels and the elasticity for bottom layers of the Earth’s crust. This paper considers the elastic interaction of crustal blocks bounded by deep faults in the form of three-layer panels. Using the hypothesis of linear measurement of deformations along with the height of the board and the elastic limit for the lower layer of the Earth’s crust, calculated dependences for tectonic stresses on the elasticity and thickness of the layers of the Earth’s crust are obtained.

The Strength of Inconel 625, Manufactured by the Method of Direct Laser Deposition under Sub-Microsecond Load Duration

This paper presents the results of measurements of the spall strength and elastic-plastic proper-ties, under dynamic and static loads, of the high-strength heat-resistant nickel-chromium alloy Inconel 625, obtained by the direct laser deposition method. The structural parameters of the obtained samples and the mechanical properties during static tests were studied. According to our information, anisotropy in the structural parameters operates primarily at the level of plastic deformation of alloys. Shock compression of the additive alloy Inconel 625 samples in the range of 6–18 GPa was carried out using a light-gas gun, both along and perpendicular to the direction of the deposition. The strength characteristics were determined from the analysis of the shock wave profiles, which were recorded using the VISAR laser velocimeter during the loading of samples. It was found that the value of the spall strength of additive samples does not depend on the direction of deposition, and the Hugoniot elastic limit of samples loaded perpendicular to the deposition direction is about ~10% higher. With an increase in the maximum compression stress, the material’s spall strength increases slightly, but for both types of samples, a slight decrease in the Hugoniot elastic limit was observed as the compression stresses increase. On the basis of the measured wave profiles, shock Hugoniots of the samples of the alloy Inconel 625, loaded both along and perpendicular to the direction of deposition, are constructed in this pressure range.

ANALYSIS OF THE ENGINE STRUCTURAL AND THERMAL STRESS

The paper aims to analyse the demands of four-stroke naval pistons. To begin with, a brief analysis of the evolution of shipbuilding was made. Mechanical requests are produced by the gas pressure force and inertial force of the alternate moving masses. Under its action the piston suffers an axial deformation. The thermal demands appearing in the engine are all the more important as the engine power is higher. The possibility of calculating them is more difficult due to the complexity of the thermogazodynamic phenomena in the engine cylinder. Thus, in the piston head, which comes in contact with both the hot gases and the fresh (much cooler) load, a non-stationary heat flow is installed which leads to a certain thermal regime of the engine. Considering the demands outlined in the last chapter, they lead to the final conclusion that although the most unfavourable loading situation was considered as the maximum pressure during the processes and even exaggerated in establishing the working conditions, the piston is still close to the elastic limit. This demonstrates that the way of calculating the dimensions of the piston is correct and safe, as long as its constructive dimensions are not oversized.

Effect of implantoplasty on the elastic limit of dental implants of different diameters

Background Implantoplasty reduces both implant diameter and the thickness of its walls, subsequently reducing the ability of the implant to resist fracture in response to functional load. In combination with an increase in the crown-implant ratio due to bone loss, this could increase the lever effect, which in presence of high masticatory forces or parafunctional habits, could lead to complications such as fracture of the implant or loosening of the prosthetic screw. Objectives To determine the elastic limits of internal connection, dental implants of different designs and diameters after an implantoplasty. Materials and methods This in vitro study included 315 tapered internal connection titanium dental implants, the threads of which were removed with an industrial milling machine—for standardized implantoplasty (IMP1; n = 105)—or with the conventional approach—manually, using high-speed burs (IMP2; n = 105). The remaining 105 implants were used as controls. The final implant diameters were recorded. The quality of the newly polished surfaces was assessed by scanning electron microscopy. All implants were subjected to a mechanical pressure resistance test. A Tukey’s test for multiple comparisons was used to detect differences in the elastic limit and final implant diameters between the implant groups. Results There were statistically significant differences in the elastic limit between the IMP1, IMP2, and control groups (p < 0.05). Furthermore, the implant diameter was significantly smaller in the IMP1 and IMP2 groups (p < 0.05). Scanning electron microscopy revealed smooth implant surfaces in the IMP1 and IMP2 groups, with some titanium particles visible in the IMP1 group. Conclusions Implantoplasty significantly decreased the elastic limit of internal connection titanium dental implants, especially in those with a smaller diameter (3-3.5 mm).

High-Strain Deformation and Spallation Strength of 09CrNi2MoCu Steel Obtained by Direct Laser Deposition

In this work, the critical fracture stresses during spalling of high-strength steel 09CrNi2MoCu samples obtained by direct laser deposition (DLD) were measured under shock compression of up to ~5.5 GPa. The microstructure and mechanical properties of DLD steel samples in the initial state and after heat treatment were studied and compared to traditional hot rolled one. The microstructural features of steel before and after heat treatment were revealed. The heat treatment modes of the deposit specimens on their strength properties under both static and dynamic loads have been investigated. The spall strength of the deposited specimens is somewhat lower than the strength of steel specimens after hot rolling regardless of their heat treatment. The minimum elastic limit of elasticity is exhibited by the deposit specimens. After heat treatment of the deposit samples, the elastic limit increases and approximately doubles. Subsequent heat treatment in the form of hardening and tempering allows obtaining strength properties under Hugoniot loads in traditional hot-rolled products.

Elastic ice microfibers

Ice is known to be a rigid and brittle crystal that fractures when deformed. We demonstrate that ice grown as single-crystal ice microfibers (IMFs) with diameters ranging from 10 micrometers to less than 800 nanometers is highly elastic. Under cryotemperature, we could reversibly bend the IMFs up to a maximum strain of 10.9%, which approaches the theoretical elastic limit. We also observed a pressure-induced phase transition of ice from Ih to II on the compressive side of sharply bent IMFs. The high optical quality allows for low-loss optical waveguiding and whispering-gallery-mode resonance in our IMFs. The discovery of these flexible ice fibers opens opportunities for exploring ice physics and ice-related technology on micro- and nanometer scales.

Influence of pore shape on impact dynamics characteristics of functionally graded brittle materials

Improving the impact energy dissipation capacity of functionally graded brittle materials through pore design will help avoid or delay failure. In order to improve the impact energy dissipation capacity of functionally graded brittle materials, pores with specific shapes can be implanted inside them. The effect of pore shape on the impact properties of functionally graded brittle materials was investigated using a lattice-spring model that can quantitatively represent the mechanical properties of functionally graded brittle materials. The calculated results show that the pores with negative Poisson’s ratio such as inner-concave triangle, fourth-order star, and inner-concave hexagon are easy to collapse under the impact, while the square and square-hexagon pores have the strongest resistance to deformation. For all seven pore shapes, the Hugoniot elastic limit of the samples decreased gradually with increasing porosity, and the Hugoniot elastic limit did not change with the change of piston velocity. The propagation velocity of the deformation wave increases with the piston velocity and the velocity of the particle corresponding to the Hugoniot state behind the deformation wave increases accordingly. The principle that pores can enhance the macroscopic impact energy dissipation capacity of functionally graded brittle material samples revealed in this paper will contribute to the prevention of sample impact failure and provide guidance for the optimal design of impact kinetic properties of samples.

Pulmonary Stretch and Lung Mechanotransduction: Implications for Progression in the Fibrotic Lung

Lung fibrosis results from the synergic interplay between regenerative deficits of the alveolar epithelium and dysregulated mechanisms of repair in response to alveolar and vascular damage, which is followed by progressive fibroblast and myofibroblast proliferation and excessive deposition of the extracellular matrix. The increased parenchymal stiffness of fibrotic lungs significantly affects respiratory mechanics, making the lung more fragile and prone to non-physiological stress during spontaneous breathing and mechanical ventilation. Given their parenchymal inhomogeneity, fibrotic lungs may display an anisotropic response to mechanical stresses with different regional deformations (micro-strain). This behavior is not described by the standard stress–strain curve but follows the mechano-elastic models of “squishy balls”, where the elastic limit can be reached due to the excessive deformation of parenchymal areas with normal elasticity that are surrounded by inelastic fibrous tissue or collapsed induration areas, which tend to protrude outside the fibrous ring. Increasing evidence has shown that non-physiological mechanical forces applied to fibrotic lungs with associated abnormal mechanotransduction could favor the progression of pulmonary fibrosis. With this review, we aim to summarize the state of the art on the relation between mechanical forces acting on the lung and biological response in pulmonary fibrosis, with a focus on the progression of damage in the fibrotic lung during spontaneous breathing and assisted ventilatory support.