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Purpose. The purpose of the study was to determine the stress-strain state and operating characteristics of the existing steel-reinforced-concrete span structure under the railway after long-term operation under static and dynamic loads. Methodology. To achieve the goal, full-scale surveys of the existing bridge crossing were carried out, more attention was focused on the steel-reinforced concrete span structure, the conditions and features of its operation were determined, and static and dynamic tests were conducted. During the tests, the general deformations of the span structures (vertical and horizontal deflections) and the stress state in the elements of the structures under different load schemes were measured. During dynamic tests, registration of static and dynamic component deflections and stress changes in structural elements during the passage of rolling stock along the span structure was carried out. The interaction of the span structure with the rolling stock, the influence of uneven approaches to the bridge on the excitation of the rolling stock was investigated. Findings. The values of stresses in the elements of the steel-reinforced-concrete span structure were obtained when the test load was installed in the position at which the greatest stresses and deformations should occur in the test elements, the frequencies of natural and forced oscillations of the span structure were measured, the dynamic coefficient, the dynamic deflections of the main beams were determined, the values decrements of oscillations of the frequency of natural and forced oscillations. The dynamic interaction of the rolling stock with the steel-reinforced concrete span structure was studied. Analytical assumptions in the design of steel-reinforced-concrete span structures of bridges have been confirmed. Originality In the work, a study of the stress-deformed state of the steel-reinforced concrete span structure of the railway bridge after long-term operation, the simultaneous operation of the span structure with rolling stock was carried out. Practical value. The operating conditions of the steel-reinforced-concrete span structure of the railway bridge, static and dynamic characteristics of its operation, the interaction of the rolling stock with the span structure, the influence of the unevenness of the approach track to the bridge on the dynamic interaction of the span structure and the rolling stock are determined. Practically confirmed analytical calculations of deformation and dynamic characteristics of steel-reinforced-concrete span structures of bridges, the joint operation of steel beam and reinforced concrete slab is ensured to a sufficient extent and corresponds to theoretical assumptions.

Relevance: assessment of the possibility of preserving the mineral resource base of the enterprise by minimizing the reserves in the security areas under the Urup River while maintaining the stability of the Earth's surface. Objective: to determine and propose the optimal parameters of ore extraction technologies in the zone of influence of the Urup River with the preservation of the earth's surface under technogenic influence. Objects: the Earth's surface, native massifs and artificial massifs made of hardening mixtures erected in the developed treatment space. Methods: modeling of safe conditions for the extraction of ores from pillars in the zone of influence of the river, carried out using a complex of well-known and original laboratory, analytical and field methods. Determination of the patterns of behavior of water-saturated rocks is carried out in the laboratory with imitation of processes in riverine pillar, by assessing the phenomenon of immersion of the pillar in the water-weakened soil of the treatment work. Results. Quantitative values of horizontal deformations limiting for these conditions are determined. The method of forecasting the process of rock movement based on calculations is substantiated. A methodology was developed to assess the possibility of applying the technology of continuous ore extraction in the Urup River zone, based on the permissible deformations of the Earth's surface and compression of the laying mixtures. The authors experimentally justified possibility and boundary conditions of dredging of stocks of pillars under the river by the pillar-and-room development system with the laying of the worked-out space with solid mixtures to ensure the safety of the Earth's surface. Measures are recommended to ensure the stability of the outcrops of the treatment workings in the period between the formation of the treatment chambers and their laying, on the direction of development of the treatment works and to determine the permissible spans of the workings.

The aim of this work is to study the relation between S -expansions and other transformations of Lie algebras. In particular, we prove that contractions, deformations and central extensions of Lie algebras are preserved by S -expansions. We also provide several examples and give conditions so transformations of reduced subalgebras of S -expanded algebras are preserved by the S -expansion procedure. [ABSTRACT FROM AUTHOR]

Many earth dams are damaged by shearing under seismic stresses effect. In Algeria, earthquake of 21 May 2003, of magnitude Mm = 6.9 on Richter scale, considered as the most violent for more than 20 years, occurred about 70 km east of Algiers’s capital, where a large number of structures were damaged in this region. The aim of this article is to present a numerical analysis of an earth dam in the province of Oum-Elboughi. The objective is to show the influence of compressive seismic waves and the effect of foundation deph on dam behavior .The stady was carried out using a 2D finite difference method (FDM) using the FLAC 2D calculation code. In this analysis, a soil nonlinear behaviour is provided by a combined Hardin/Drnevich hysteretic damping behaviour model with Mohr–Coulomb elasto-plastic model. Results that are presented in terms of deformations and shear stresses developed at the dam and dam foundation show that the most critical area is located on the downstream side of the dam. Increasing the foundation depth decreases the value of horizontal stress, while decreasing it increases the dam instability risk. [ABSTRACT FROM AUTHOR]

This paper studies the propagation of heat and thermal deformations induced by a laser pulse in a thin metal sheet made of stainless steel. The visualization of the propagation of heat and thermal deformations is carried out using a thermal imaging camera and a thermo/mechanoluminescent composite material made from a polymer and a phosphor powder and applied on the surface of the studied sheet. The heat propagation rate in the sheet is determined by the thermoluminescence of the composite layer. The deformations caused by the shock and breakdown of the sheet using a peen with a cone-shaped point are also examined by the mechanoluminescence of the composite layer applied on the sheet surface. The paper shows that the used composite material visualizes the propagation rate and distribution of temperature in the area affected by the laser pulse and mechanical stresses and deformations in the shock damage (rupture) area of a metal sheet with a high spatial and temporal resolution. [ABSTRACT FROM AUTHOR]

Background. Modern production of hollow products by hot reverse extrusion poses the task of reducing energy consumption and reducing metal costs for the manufacture of such products. Such problems can be solved by using them for extruding square-shaped blanks. Goal. Determination using the finite element method (FEM) of the parameters of hot reverse extrusion of hollow products from round and square blanks and comparison of the results of theoretical studies. Methodology of implementation. Theoretical studies of force modes of extrusion, specific forces and stress-strain state of metal were carried out by simulation using MSE in the DEFORM software environment. The results. Modeling of the process of hot reverse extrusion from low-carbon steel of a hollow product with protrusions on the end of the bottom part was carried out with the help of MSE. Round and square blanks are used. Extrusion forces, forces for removing punches from deformed blanks and forces for pushing out products from matrices are established. The distribution of specific forces on the deforming tool is revealed. The stress-strain state and temperature distribution in the deformed metal at the end of extrusion were determined. Evaluation of the working of the metal structure by hot plastic deformation was carried out and the obtained parameters were compared. Conclusions. The use of square-shaped blanks during hot reverse extrusion of hollow products is substantiated. [ABSTRACT FROM AUTHOR]

There are numerous talus cones that have formed by long-term geological processes and sudden hydrological events in the Small Cold Valley (High Tatras National Park in Slovakia). Frequent hiking trails lead here; therefore, their safeness needs to be monitored due to recent rock avalanches and landslides. A complex methodology for monitoring changes in talus cones was developed to determine the extent, pace, nature, and origin of the morphological changes in the land in this complex high-mountain terrain. Non-contact UAS photogrammetry with SfM-MVS processing was applied as a quick, reliable, and environment-friendly data acquisition method. For proper georeferencing, a network of GCPs and stabilized surveying points were established by terrestrial geodetic surveying. Together with an evaluation of the methodology, the results comparing the actual state of a talus cone in 2018 and 2022 (after the significant hydrological event) are presented. Comparing and analyzing spatial models represented by point clouds, with an accuracy of centimeter level, was obtained. The detected morphological changes reached values in meters. A differential model expresses the distribution of the morphological changes. In conclusion, geodetic and geological knowledge is synthesized to evaluate the phenomena occurring in this territory. [ABSTRACT FROM AUTHOR]

The black rat (Rattus rattus) has become in a commensal relationship with humans and has been responsible for obvious damage to agriculture annually. In this study, clodinafop-propargyl bait (0.98%) was introduced to the adult male rats for seven days under laboratory conditions using a non-choice feeding method. The impact of the compound on the body and some organs' weights and functions was studied. Histopathological changes of the liver, kidney, and testis as well as sperm count, sperm morphology, vitality and motility percent were recorded. The efficiency of clodinafop-propargyl bait (0.98%) was evaluated under field conditions of crop stores. The results demonstrated that the body weight and testis of rats significantly decreased obviously after treatment. As well as, the treatment caused immoderate loss of water through the skin, losing appetite and slow movement of rats. While weights of the liver and kidney of treated rats significantly increased. In addition, the appearance of morphological and histopathological alterations in the liver, kidneys, and testis were observed. Also, significant elevation in serum (ALT and AST) enzymes, urea, creatinine and uric acid levels compared with control after treatment were recorded. Furthermore, sperm count, motility and vitality percentages significantly decreased (p≤0.05) in treated rats compared with controls. There were perspicuous abnormalities in the form of the head, neck, and tail of the spermatozoa in the treated rats. Regarding, sperm motility; non-progressive and immotile grades were significantly increased in treated rats compared with controls. Moreover, clodinafop-propargyl bait (0.98%) proved efficient under crop store conditions as it caused an 86.78 % reduction in the rat population. In conclusion, clodinafop-propargyl bait has a strong toxic impact on the liver, kidneys and reproductive system of male black rats affecting their fertility by destroying testicular integrity and function. Furthermore, the field results proved these impacts and achieved good results. We can conclude that this compound can be used in the control of black rats and can be used in rodent control programs. [ABSTRACT FROM AUTHOR]

This paper deals with some properties of the infinitesimal form of the Kobayashi pseudo-distance. This form is shown to be a continuous function in the parameters of a differentiable deformation of each Riemann surface. It is also shown in this paper that, each non elliptic Riemann surface has a non-trivial differentiable deformation [ABSTRACT FROM AUTHOR]

This manuscript presents new experimental methods for testing the ex vivo tensile properties of the uterosacral ligaments (USLs) in rats. The USL specimens ( n = 21 ) were carefully dissected to preserve their anatomical attachments, and they were loaded along their main in vivo loading direction (MD) using a custom-built uniaxial tensile testing device. During loading, strain maps in both the MD and the perpendicular direction (PD) were collected using the digital image correlation technique. The mean (± S.E.M.) maximum load and displacement at the maximum load were 0.98 ± 0.30 N and 17.53 ± 3.87 mm, respectively. The USLs were found to be highly heterogeneous structures, with some specimens experiencing strains in the MD that were lower than 5 % and others reaching strains that were up to 60 % in the intermediate region. At 0.5 kPa stress, a value reached by all the specimens, the mean strain in the MD was 9.15 ± 1.30 % while at 5 kPa stress, a value achieved only by 9 out of the 21 specimens, the mean strain increased to 23.87 ± 3.64 % . Under uniaxial loading, the specimens also elongated in the PD, with strains that were one order of magnitude lower than the strains in the MD; at the 0.5 kPa stress, the mean strain in the PD was recorded to be 0.69 ± 0.66 % and, at the 5 kPa stress, the strain in the PD was 6.99 ± 2.87 % . The directions of maximum principal strains remained almost unchanged with the increase in stress, indicating that little microstructural re-organization occurred due to uniaxial loading. This study serves as a springboard for future investigations on the supportive function of the USLs in the rat model by offering guidelines on testing methods that capture their complex mechanical behavior. [ABSTRACT FROM AUTHOR]

Present theory investigates the dimensionless vibration frequencies, deformations, and stresses for multilayered and sandwich arches using exponential shear and normal deformation theory (ESNDT). Present studies consider the effect of [1+(z/R)]radius of curvature while selecting the displacement field of arches under the action of uniform load. It includes the effects of transverse shear (γxz≠0) and transverse normal deformation(εz≠0) i.e., effect of thickness stretching. The governing relations are obtained using the Navier's method, and Hamilton's virtual work principle. The proposed layered arches are completely free from shear correction, and its top and bottom surfaces is satisfies zero traction free end conditions. Present study obtained very accurate natural frequencies for layered sandwich arches than other theories because, available literature not considered the thickness stretching effect i.e.,(εz=0). Hence, the present scientific investigation accounts the effect of thickness stretching i.e.,(εz≠0). However, the non-availability of exact elasticity results of bending and dynamic responses for layered sandwich arches. Present theory is obtained vibration frequencies, displacements, and stresses of layered composite and sandwich arches; the results are compared and validates through prior published literature.

This paper focuses on investigating the stability of a deep foundation pit with hard surrounding rocks at different excavation stages with different supporting schemes by means of numerical calculations. The supporting schemes in question were combinations of one fixed vertical support and four varied transverse supports. Drilled grouting piles were used as vertical supports, and the commonly used steel bracings and prestressed anchorages served as transverse supports. The parameters used to evaluate the stability of the foundation pit at different excavation stages included the lateral displacements of the surrounding rocks, the settlement of the surrounding ground, the axial forces of steel bracings, and displacements at the tops of the drilled grouting piles. Simulation results showed that when a transverse supporting scheme consisting of one-layer steel bracings and prestressed anchorages set at 9 m and 22.5 m underground, respectively, was adopted, the lateral displacements of the surrounding rocks and settlement of the surrounding ground at different excavation stages were the largest compared to those under the other three transverse supporting schemes, while the corresponding values were lower compared to those allowed in Chinese standard GB50007-2011, demonstrating that this kind of supporting scheme is effective in terms of ensuring the safety of the foundation pit at different excavation stages. Moreover, the setting techniques for this kind of supporting scheme were relatively simple, and the corresponding influences of supporting element arrangements on excavation techniques were the lowest. Therefore, one-layer steel bracings and one-layer prestressed anchorages constituted the most suitable transverse supporting scheme for excavating a deep foundation pit with hard surrounding rocks.

Generation of electricity in nuclear power plants have supplied further energy to society in the world, and remain arising of radioactive waste as results of performance industry with activity. In fact, all of radioactive waste encourage some categories types as following; two most important points are high-level waste (HLW) and low- and intermediate-level waste (LLW). To end disposal completely, every country operated Nuclear Energy plant foresees further deep geological repository. This study conducted out measurement of deformations due to changing suction, which were volume change, axial strains and radial strains. Used triaxial compression apparatus was improved to be possible controlling suction for air flow circulation, and measured both axial and radial strains and variations of mass under drying-wetting cyclic in suction. Required suction rage is from 2.8 MPa to 296 MPa, and it corresponds to from 98.0 % to 11.0 % in relative humidity. Axial strains and radial strains for all of specimens have described obviously the shrinkage phenomena due to drying and wetting cyclic process regard to suction potential, and bentonite-sand mixture specimens are statically compacted. Axial strains compare that is larger than radial strains regard to all applied suctions. Subsequently, changing of void ratio was classified into two categories, which one was elastic components and other one was plastic component, and elastic component in void ratio was remaining larger than plastic component for high suction ranges.

The article discusses the use of the finite difference method of one variable, the method of straight lines, to determine temperature stresses and strains in plates with a fixed, hinged supported or completely free contour. This method was developed by L.V. Kantorovich, the finite difference method for solving in one variable, i.e. solving the Laplace and Pousson equations. Later, this method was improved by V.A. Fadeev, L.P. Vinokurov and M.G. Slobodyansky, and in the middle of the last 20th century by P.M. Varvak. The Kirchhoff-Love hypothesis is used. It is assumed that the cross section of the plate that is flat and normal to the median plane does not distort and after deformation remains flat and normal to the median plane, the displacement of points located in the median plane of the plate is considered very small compared to the thickness. A nonstationary problem has been solved in which the temperature distribution over the thickness of the plate – h for the singularity is assumed to be nonlinear. Temperature deflections and stresses along the middle of rectangular plates with embedded, supported or completely free boundary conditions on the contour were obtained.

According to the Russian building codes, the numerical study of structures should be carried out taking into account the existing defects and damages. On the example of a U-shaped reinforced concrete frame containing damage, a comparative analysis of three cases of stress-strain state was carried out in comparison with the design scheme without damage. Also, a library of typical damages of reinforced concrete columns and proposed design models was compiled. The calculations were performed by the finite element method in LIRA-SAPR.

The average deformed fiber is a continuous and smooth function of the fourth order. The deflection and rotation of beams can be determined by various methods available in the literature. Thus, in this paper, the expression of the average deformed fiber is defined in advance, then it is considered an infinite sum of sinusoidal functions that are successively evaluated using sinusoidal trigonometric series if it is considered a periodic function, or using Fourier series if it is considered a non-periodic function. The method is examined by solving several beam problems. The results indicate that the method can be used with confidence for solving any bending beam problem. [ABSTRACT FROM AUTHOR]

The re-centring ability and durability of important bridges have been the main objectives in recent provisions of seismic design codes. To achieve better recoverability and durability for piers, this article presents a double-reinforced pier configuration, in which the outer layer is reinforced with fibre-reinforced polymer (FRP) rebar and the inner layer is reinforced with steel rebar. An equal flexural capacity design method was used to determine the double-reinforced configurations. The effects of the potentially influential design parameters on the seismic response of piers were studied and compared to those of conventional RC piers. The results show that the proposed design method can satisfy the ultimate capacity and durability demands. The double-reinforced piers had a better performance than conventional piers in terms of the ductility, post-yield stiffness and residual deformation. The maximum deformation and energy dissipation capacity of the double-reinforced piers were comparable to those of the conventional RC piers. The results also demonstrated that the proportion of steel reinforcement had a clear effect on the performance of double-reinforced piers. However, FRP reinforcement with a high modulus of elasticity should be avoided due to the adverse effect on ductility. [ABSTRACT FROM AUTHOR]

The aim of this paper is to introduce 3-Hom-ρ-Lie algebra structures generalizing the algebras of 3-Hom-Lie algebra. Also, we investigate the representations and deformations theory of this type of Hom-Lie algebras. Moreover, we introduce the definition of extensions and abelian extensions of 3-Hom-ρ-Lie algebras and show that associated to any abelian extension, there is a representation and a 2-cocycle. [ABSTRACT FROM AUTHOR]

Bar reinforced concrete structures, which include piles, in real working conditions perceive a whole range of internal force factors. Axial tension-compression forces, bending moments and shear forces are the most commonly perceived internal force factors. Of particular interest is the effect on the cross section of the shear force. If a complex curly shape is replaced by elementary form, then the calculation is not difficult. However, when calculating the composite cross section, there is no unambiguous solution. In accordance with the adopted regulatory documentation, it is necessary to accept only a main part, while discarding the surrounding areas. It is important to study the configuration of the shape of a complex section for the perception of a shear force. The purpose of the work was to refine the account of the entire complex section using numerical simulation by the finite element method, analytical calculations and small-scale experiments. Determination of further practical application of the obtained results on real structures was also the goal of the study. The parameters of the distribution of shear force between the main rib and flanges were obtained by numerical analysis and small-scale experiments. Numerical models of rectangular and tee cross sections beams have been developed. Analytical dependences were studied and full-scale tests of reinforced concrete beams of various sections were carried out. It has been established that when taking into account the work of the entire cross-section, the bearing capacity of concrete for the action of a shear force is 20% greater than when calculating only the main section without taking into account the shelves. [ABSTRACT FROM AUTHOR]

A characteristic class for deformations of foliations called the Fuks–Lodder–Kotschick class (FLK class) is studied. It seems unknown if there is a real foliation with nontrivial FLK class. In this paper, we show some conditions to assure the triviality of the FLK class. On the other hand, we show that the FLK class is easily to be nontrivial for transversely holomorphic foliations. We present an example and give a construction which generalizes it. [ABSTRACT FROM AUTHOR]

Encasing glass fiber reinforced polymer (GFRP) beam with reinforced concrete (RC) improves stability, prevents buckling of the web, and enhances the fire resistance efficiency. This paper provides experimental and numerical investigations on the flexural performance of RC specimens composite with encased pultruded GFRP I-sections. The effect of using shear studs to improve the composite interaction between the GFRP beam and concrete was explored. Three specimens were tested under three-point loading. The deformations, strains in the GFRP beams, and slippages between the GFRP beams and concrete were recorded. The embedded GFRP beam enhanced the peak loads by 65% and 51% for the composite specimens with and without shear connectors, respectively. Moreover, a non-linear Finite Element (FE) model was developed and validated by the experimental results to conduct a parametric study. The peak loads of the composite specimen without shear studs increased by 14% and 31% and of the composite specimen with shear studs increased by 20% and 32% for the compressive strength of 35 MPa and 45 MPa, respectively. [ABSTRACT FROM AUTHOR]

The aim of the note is to give a complete description of all the hyperplane sections of the projective bundle associated to the tangent bundle of P 2 under its natural embedding in P 7. As an application one obtains a description of all possible deformations in the homogeneous space SL 3 (C) / B of the co-dimension one sub-scheme which is the union of two fundamental Schubert divisors. [ABSTRACT FROM AUTHOR]

In the early stages of the Moon's formation, its growing lithosphere experienced complex time-varying temperature and gravitational stresses. Despite the subsequent intense impact transformation of the surface, during the gravimetric study of the GRAIL space mission, the presence of ancient deep intrusions was detected. The analysis of linear gravitational anomalies shows the expansion of the outer rigid layer of the Moon at a certain early stage of its evolution due to the excess of temperature stresses over gravitational compression. Obtaining the dependence of the time interval of the lithosphere expansion on a number of dimensionless thermal conductivity parameters will make it possible to refine the existing models of the thermal and geochemical evolution of the early Moon. [ABSTRACT FROM AUTHOR]

In this paper, the author discusses the deformations of compact complex manifolds with ample canonical bundles. It is known that a complex manifold has unobstructed deformations when it has a trivial canonical bundle or an ample anti-canonical bundle. When the complex manifold has an ample canonical bundle, the author can prove that this manifold also has unobstructed deformations under an extra condition. [ABSTRACT FROM AUTHOR]

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Purpose. The research purpose is to determine the instability zones in the host rocks and the dynamics of propagation of active fracturing zones to ensure the stability of the rock mass surrounding the mine workings. Methods. The research uses a set of analytical and experimental studies to determine the dynamics of the deformation process development in the coal-rock mass surrounding the mine workings. Mathematical modeling of the stress-strain state of the rock mass surrounding the active extraction workings is performed using the numerical method of finite elements in modern AN-SYS, Mergel and KMS-III software products. Findings. The influence has been studied of the mine working section shape and the coal seam dip angle on the value of the maximum stresses that arise in the rock mass when the mine working is fastened with the roof-bolt support. The instability zones in the host rocks and the dynamics of propagation of active fracturing zones have been determined both ahead of the front of the conducted mine working and on its sides for rocks of different strength. Originality. For the conditions of the Karaganda coal basin, the dependence of a change in the development of conventional inelastic deformation zones (CIDZ) on the host rock strength has been revealed. The influence of the coal seam dip angle on the dynamics of stratifications around preparatory working has also been substantiated. In addition, new data have been obtained on the influence of the roof rock strength on the stratification of the rock mass surrounding the mine working. Practical implications. By determining instability zones in the host rocks and the dynamics of propagation of active fracturing zones, it is possible to control geomechanical processes in the border rock mass of a mine working and influence it in order to prevent the occurrence of negative rock pressure manifestations. The data obtained are the basis for the development of recommendations on the use of roof-bolting technology for fastening extraction workings to ensure their stability and reduce the cost of their operation. [ABSTRACT FROM AUTHOR]

We present a framework for the computation of the Hopf 2-cocycles involved in the deformations of Nichols algebras over semisimple Hopf algebras. We write down a recurrence formula and investigate the extent of the connection with invariant Hochschild cohomology in terms of exponentials. As an example, we present detailed computations leading to the explicit description of the Hopf 2-cocycles involved in the deformations of a Nichols algebra of Cartan type $A_2$ with $q=-1$ , a.k.a. the positive part of the small quantum group $\mathfrak{u}^+_{\sqrt{-\text{1}}}(\mathfrak{sl}_3)$. We show that these cocycles are generically pure , that is they are not cohomologous to exponentials of Hochschild 2-cocycles. [ABSTRACT FROM AUTHOR]

The calculation for stability against progressive collapse in a dynamic setting, regulated by the norms, contains general recommendations on the possibility of taking into account a pliable foundation and including non-load-bearing elements in the calculation model without determining the limits of their applicability. The results of experimental studies and numerical analysis of a reinforced concrete experimental design of a spatial frame - a fragment of the frame of a multi-storey building in limiting and transcendental states are compared. The features of deformation of the structural system before and after the beyond-design impact, which causes its sudden structural restructuring, are established. Numerical studies were performed with and without considering the pliable foundation, as well as including or not including non-load-bearing elements in the calculation. Satisfactory agreement between the data of experimental studies and the results of dynamic calculation has been obtained. As one of the variants of the calculation model, a modified scheme was adopted, the constituent part of which are the elements of the calculation model of the second level - a fragment of the frame, modeled by volumetric and flat finite elements. It has been established that the results of the dynamic calculation of the experimental fragment are consistent with the experimental data only when taking into account the elements of the load device and real boundary conditions, including the deformable base.

This work is about study of the mechanical behaviour of unidirectional Kevlar / Epoxy composite laminates according to different failure criteria. Varying strength parameters values, makes it possible to compare the ultimate mechanical characteristics obtained by the criteria of Tsai-Hill, Norris, Fisher, Ashkenazi and Tsai-Wu. The epoxy matrix of the material in question is reinforced with up to 60% of its volume by aramid fibers. The stack of four layers composing the arbitrarily oriented and alternating [+?/-?]S materials results in balanced symmetrical laminates. The laminate is subjected to uniaxial tensile membrane forces. Estimate of their ultimate strengths and the plotting of the failure envelope constitute the principal axis of this study. Using the theory of maximum stress, we can determine the various modes of damage of the composite. The different components of the deformation are presented for different orientations of fibers.

New optical materials, in particular mixed lithium niobate-tantalate (LNT) solid solutions, are promising for application in photonics and microelectronics. Proton exchange is one of the widely used methods for producing low-contrast optical waveguides. The structure and properties of the proton exchange layers in X - and Z -cut samples were systematically studied using various structural and integrated optical methods. Direct proton exchange leads to the formation of a waveguide layer with a step-like refractive index profile. The waveguide-substrate boundary is clear (not blurred). At this boundary, the parameters of the crystal lattice change abruptly. Proton exchange leads to with the formation of deformation twins and surface damage of the LNT crystal structure. Indices and geometric parameters of surface damage were determined. The results of phase analysis of the samples indicate the presence of β -phases with high degrees of deformation of the crystal lattice. The calculated kinetic parameters of proton diffusion in LNT are significantly lower than for lithium niobate crystals, which is due to both the tantalum impurity and the greater disorder of the crystal lattice, and this leads to a decrease in the increment of the refractive index. The results provide a physical basis of diffuse process and design and fabrication of proton exchange waveguides in mixed LNT solid solutions. • Deformation twins were discovered in the proton exchange layer in a mixed lithium niobate-tantalate solid solution. • A clear waveguide layer – substrate boundary, at which the lattice parameters change abruptly, was observed by using TEM analysis. • Direct proton exchange leads to damage to the surface of a non-polar X -cut in the form of parallel oriented stripe-like defects with a crystallographic orientation [123]. • The low-energy activation and high diffusion coefficients in lithium niobate-tantalate solid solution, unlike lithium niobate, lead to the formation of the β -phases with strong deformations of the crystal lattice. [ABSTRACT FROM AUTHOR]