Damage Accumulation Process Research Articles

Studies on structural heterogeneity of high-strength sheet materials

The work is devoted to the actual scientific and practical task of applying the methods of researching the processes of damage accumulation in metals under the conditions of active operation of structures and selecting the necessary parameters characterizing the degree of material degradation to assess the load-bearing capacity of structural elements, taking into account their current damage.
 The approbation of the express control method for diagnosing the current state of the surface of a large area based on the characteristics of the dispersion of material hardness values is described. It is shown that it is possible to obtain a quantitative characteristic of the state of the metal using the LM - hardness method, according to which the parameters of the dispersion of its values during mass measurements of hardness are accepted as informative signs of the state of the metal. Experimental results were obtained during the study of high-strength materials such as Armox 500T, Hardox 450, etc. The obtained results made it possible to improve the quality of non-destructive testing of metal by the characteristics of dispersion of material hardness values and to perform a number of practical works on assessing the condition of real metal blanks used in the creation of responsible technical products or structural elements

Mechanical Properties Degradation of Fiberglass Tubes during Biaxial Proportional Cyclic Loading.

Composite structures during an operation are subjected to various types of external loading (impact, vibration, cyclic, etc.), which may lead to a decrease in mechanical properties. Previously, many experimental investigations of the mechanical behavior of composites under uniaxial cyclic loading were carried out. Acquisition of new data on the reduction of composite materials' mechanical characteristics under conditions of multiaxial cyclic loading, as well as verification of existing models for calculation of the residual properties, are relevant. Therefore, this work is devoted to the experimental investigation of the mechanical behavior of fiberglass tubes under proportional cyclic loading. Static and fatigue tests were carried out under tension with torsion conditions. Inhomogeneous strain fields were obtained using a non-contact optical video system VIC-3D. The structural damage accumulation processes were analyzed by an AMSY-6 acoustic emission signals recording system. Surface defects were determined using a DinoLite microscope. Residual dynamic elastic modules were calculated during fatigue tests, and fatigue sensitivity curves were built. Data was approximated using various models, and their high descriptive capability was revealed. Damage accumulation stages were determined. The dependence of the models' parameters on a stress state were observed. It was concluded that multiaxial cyclic loading leads to a significant decrease in mechanical properties, which should be taken into account in composite structure design.

Numerical Simulation of Failure Behavior of Reinforced Concrete Shear Walls by a Micropolar Peridynamic Model.

A reinforced concrete shear wall is an important building structure. Once damage occurs, it not only causes great losses to various properties but also seriously endangers people's lives. It is difficult to achieve an accurate description of the damage process using the traditional numerical calculation method, which is based on the continuous medium theory. Its bottleneck lies in the crack-induced discontinuity, whereas the adopted numerical analysis method has the continuity requirement. The peridynamic theory can solve discontinuity problems and analyze material damage processes during crack expansion. In this paper, the quasi-static failure and impact failure of shear walls are simulated by improved micropolar peridynamics, which provides the whole process of microdefect growth, damage accumulation, crack initiation, and propagation. The peridynamic predictions are in good match with the current experiment observations, filling the gap of shear wall failure behavior in existing research.

Investigation of compression after impact failure in carbon fiber reinforced polymers using acoustic emission

Although several studies have been performed, the compression after impact (CAI) failure of CFRP is still not entirely understood. It is still unclear what sequence of events determines the onset of failure in CAI tests and how the different damage modes are involved in this process. To experimentally investigate this matter, the present work relies on acoustic emission (AE) monitoring and advanced acoustic signal analysis. A series of preliminary tests was conducted to correlate damage modes with recorded acoustic waveforms. Four types of waveforms were separated and associated to different damage modes. Following the preliminary tests, AE was monitored in actual CAI tests. A damage accumulation study was conducted combining three indicators, namely wavelet packet components, sentry function and energy b-value. The results evidence different phases in the damage accumulation process that were not shown in previous literature. In all specimens, the onset of the unstable damage accumulation appeared to be triggered by an intermediate frequency acoustic event associated to a combination of matrix cracking and fiber-matrix debonding, occurring at 80% of failure displacement.

Non-Extensive Statistical Mechanics in Acoustic Emissions: Detection of Upcoming Fracture in Rock Materials

Acoustic emission (AE), recorded during uniaxial compressive loading with constantly increasing stress and stepped stress increments until the fracture of prismatic marble specimens, were analyzed in terms of non-extensive statistical mechanics (NESM). Initially introduced by Tsallis, NESM has proven to be an autonomous robust theoretical framework for studying fracture mechanisms and damage evolution processes during fracture experiments in specimens made of brittle materials. In the current work, the time intervals of the recorded AE data are analyzed in terms of NESM. For each examined specimen, the corresponding q entropic indices and the βq parameters were calculated, and their variability in terms of the stress applied were studied. Furthermore, a possible linear relationship between the entropic index q and the parameter βq was examined, and it was investigated whether the observed deviation from monotonicity between q and βq may signal increased accumulation of damage, eventually leading to the final fracture of the specimens. Through this work, the emergence of an additional pre-failure indicator (i.e., the deviation from monotonicity between q and βq) alongside well-established ones can provide further insight regarding the underlying crack development mechanisms and damage accumulation processes during the fracture of rock materials.

Fatigue damage evolution and self-healing performance of asphalt materials under different influence factors and damage degrees

This paper determines the self-healing performance and damage accumulation process of asphalt materials under different damage degrees and influence factors by the fatigue-healing-fatigue (F-H-F) time sweep test. A comprehensive index HF is proposed to characterize the fatigue-healing performance of asphalt materials. The results show that with the increase of rest time and temperature, the HF value of asphalt materials increases. The newly proposed fatigue damage factor DR fully considers the energy dissipation history in the fatigue test process, and the mathematical model of damage accumulation based on DR can better characterize the nonlinear evolution process of asphalt material fatigue damage.

The role of hardening and roughening during the incubation period in water droplet impingement erosion of Ti–6Al–4V

The present work investigates the role of surface hardening and roughening on the damage accumulation during the incubation period in water droplet erosion (WDE). Water droplet erosion tests were carried out on Ti–6Al–4V alloy at an impact velocity of 250 m/s. The evolution of hardness and surface roughness during the incubation period were evaluated using microhardness tester and Confocal Laser Scanning Microscope (CLSM). Scanning Electron Microscopy (SEM) was conducted on the impact area at several intervals during the incubation period. Finite Element (FE) simulations were performed to obtain the impact stresses on both smooth and rough surfaces. It was found that the solid surface plastically deforms by the action of the initial impingements, and as a result, hardness and surface roughness increase progressively until the end of the incubation period. The cyclic increase in hardness results in gradual improvement in the erosion strength, making the surface more resistant to the subsequent droplet impacts. However, the finite element results revealed that the dynamic surface roughening process results in higher impact stresses for the same impact pressure due to geometrical stress concentration. It is concluded that the increase in impact stresses resulting from surface roughening negates the improvement in the erosion resistance due to hardening. Hence, cyclic hardening and roughening are crucial parameters in the damage accumulation process during the incubation period.

Parametric analysis of the stress-strain and continuity fields at the crack tip under creep regime taking into account the processes of damage accumulation using UMAT

Предметом исследования является анализ полей, ассоциированных с вершиной трещины, находящейся в условиях ползучести при принятии во внимание явления накопления повреждений. Целью работы является проведение компьютерного конечно-элементного моделирования одноосного растяжения пластины с центральной горизонтальной и наклонной трещинами в условиях ползучести в плоской постановке задачи и анализ поля сплошности вблизи вершины трещины. При численном моделировании используется степенной закон ползучести Бейли--Нортона. Моделирование выполнено в многофункциональном программном комплексе SIMULIA Abaqus. Проведен анализ окружных распределений напряжений и деформаций ползучести в окрестности вершины трещины. Cтепенной закон ползучести с помощью пользовательской процедуры UMAT (User Material) пакета SIMULIA Abaqus был дополнен кинетическим уравнением накопления поврежденности Качанова--Работнова в связанной постановке. Примененная подпрограмма UMAT имеет много преимуществ при прогнозировании поврежденности материала и позволяет работать с материалами и определяющими их соотношениями, отсутствующими в библиотеке материалов Abaqus. Подпрограмма UMAT вызывается во всех точках расчета и обновляет напряжения и переменные состояния, зависящие от решения, до их значений в конце приращения. После чего рассчитываются обновленные элементы матрицы Якоби. Получены распределения напряжений, деформаций и сплошности в условиях ползучести с учетом накопления поврежденности с течением времени. Построены угловые распределения сплошности, напряжений и деформаций с течением времени на различных расстояниях от вершины трещины с применением библиотеки Matplotlib. Проведено сравнение угловых распределений напряжений и деформаций при моделировании без учета поврежденности и в случае учета накопления повреждений. Показано, что наличие поврежденности приводит к большим значениям деформаций ползучести и меньшим значениям напряжений.

EVALUATION OF RESOURCE CHARACTERISTICS OF POWER EQUIPMENT PARTS UNDER THERMAL CYCLIC LOADING

The problem of assessing the strength and resource of critical engineering facilities, the operational properties of which are characterized by multiparametric non-stationary thermo-mechanical effects, is discussed. The main degradation mechanisms of structural materials (metals and their alloys) characteristic of such objects are considered. The basic requirements for mathematical models of these processes are formulated. A mathematical model describing the processes of thermoplastic deformation and accumulation of fatigue damage during degradation of the material by the mechanism of thermal fatigue has been developed from the position of mechanics of the damaged medium (MPS). The IPU model consists of three interrelated parts: relations that determine the cyclic thermoplastic behavior of the material, taking into account the dependence on the destruction process; equations describing the kinetics of fatigue damage accumulation; strength criteria of the damaged material. The variant of the defining relations of thermoplasticity is based on the idea of the yield surface and the principle of gradiency of the velocity vector of plastic deformations to the yield surface at the loading point. This version of the equations of state reflects the main effects of the process of cyclic thermoplastic deformation of the material for arbitrary complex trajectories of combined thermomechanical loading. The variant of kinetic equations of fatigue damage accumulation is based on the introduction of a scalar damage parameter, is based on energy principles and takes into account the main effects of formation, growth and fusion of microdefects under arbitrary complex loading conditions. As a criterion of the strength of the damaged material, the condition of reaching the critical value of the damage value is used. To assess the degree of reliability and determine the limits of applicability of the developed defining ratios of MPS, calculations of the processes of thermoplastic deformation and accumulation of fatigue damage were carried out and the numerical results obtained were compared with the data of field experiments on the example of a specific applied problem. A numerical analysis of the characteristic features of the thermal fatigue durability of a compact sample with stress concentrators simulating the operation of parts in the nozzle box of a steam turbine of a nuclear power plant (NPP) is carried out. The results of calculations of fatigue damage accumulation processes during thermal pulsations are compared with experimental data. It is shown that the developed MPS model qualitatively and with the accuracy necessary for engineering calculations quantitatively describes experimental data and can be effectively used to assess the thermocyclic fatigue durability of structures with multiaxial disproportionate paths of combined thermomechanical loading.

Computer simulation of the deformed state and strength of the frame structure of a heavy uav

COMPUTER SIMULATION OF THE DEFORMED STATE AND STRENGTH OF THE FRAME STRUCTURE OF A HEAVY UAV
 The paper is devoted to the presentation of the computer simulation results of the stress-strain state and evaluation of the low-cycle strength of the frame structure of a heavy unmanned aerial vehicle (UAV) of the quadcopter type, the prototype of which was developed at NTU "KhPI". The quadcopter is built on the basis of the use of four internal combustion engines (ICE), which provide lifting power. The cycle of calculations of the stress-strain state of the frame structure, carried out to select the option required from the point of view of ensuring the required stiffness and strength, was performed using the Finite Element Method (FEM). A macro has been developed for use in the engineering software, which allows you to select the best parameters from the point of view of the required stiffness and strength of the frame. The results of calculations of the variant implemented in the design of the created UAV prototype are presented. According to the results of the analysis of the stress-strain state, it is shown that the structural parameters chosen for the steel frame of the prototype fully satisfy the conditions of minimal deformation and short-term strength. The constants included in the evolution equation for the damage parameter describing low-cycle loading, which occurs during UAV abnormal landings, have been determined. An elastic-plastic analysis of the frame structure deformation for the conditions of dangerous landing of the quadcopter was performed. Calculations of hidden damage accumulation processes in the most heavily loaded frame beams have been carried out. For the steel frame implemented in the created prototype, the possibility of satisfactory resistance to low-cycle deformation under abnormal landing conditions is demonstrated. It is shown that due to the insufficient low-cycle strength of the aluminum alloy structure, it is necessary to make structural changes in the new version of the UAV frame that is being designed.
 Key words: computer simulation, quadcopter, macro, beam structure, stress-strain state, FEM, low-cycle strength, damage.

A Novel Parameter for Fatigue Damage Assessment of Laser-Repaired Nickel-Based Alloy.

The fatigue damage assessment of laser-repaired components is critical to their service safety. However, since laser repairing is an advanced green remanufacturing technology, the current research on its fatigue mechanical behavior and fatigue damage evaluation methods is still immature. In addition, the relevant models used for the fatigue damage evaluation can only indicate the fatigue limit of components, which cannot describe the damage accumulation process of the components during the fatigue testing. Therefore, there is an urgent need to develop a fatigue damage evaluation method that can describe the fatigue damage accumulation and evolution to reveal the damage evolution mechanism during the fatigue test. In this study, based on the 3D-DIC technique, new damage parameters, i.e., strain average value and strain standard deviation, are proposed to quantitatively describe the damage status of the nickel-based components during the stress-based fatigue process. Then, based on the new damage parameters, a strain average value/strain standard deviation damage curve method is proposed to describe the damage status evolution of the components during the fatigue testing and evaluate its fatigue damage. For example, in the tensile fatigue test, the strain average value/strain standard deviation damage curves of the substrate component and the laser-repaired component can be divided into two damage stages. In the first damage stage, the damage increases slowly with the increase in the cycle number, whereas in the second damage stage, the damage increases rapidly with the increase in the cycle number. At this time, there is a demarcation point between the first damage stage and second damage stage in the strain average value damage curve and strain standard deviation damage curve. The cycle number of the demarcation point can be used as a reference value for the fatigue failure of the laser-repaired component. In addition, the electron backscatter diffraction (EBSD) technique was used to verify the validity of the evaluation results from the novel damage parameters.

Digital twin-based life-cycle seismic performance assessment of a long-span cable-stayed bridge

Long-span cable-stayed bridges often have a design service life of more than a hundred years, during which they may experience multiple earthquake events and accumulate seismic damage if they are located in seismic-prone regions. Earthquake occurrence is discretely and randomly distributed over the life cycle of a long-span cable-stayed bridge and often causes sudden drops in the structural performance instead of yearly fixed seismic performance degradation. This study thus proposes a digital twin-based life-cycle seismic performance assessment method for long-span cable-stayed bridges. The major components of this method include: (1) a seismic hazard analysis-based generation method of earthquake occurrence sequence; (2) a digital twin-based structural response prediction method considering lifetime earthquake occurrence and sequence; and (3) a service life quantification method. The proposed method is applied to a scaled long-span cable-stayed bridge with a series of shake table tests. The results show that the digital twin can closely reproduce the life-cycle seismic response of the bridge under sequential earthquakes. The proposed assessment method provides a more intuitive presentation of the life-cycle seismic damage accumulation process and a more accurate estimation of the service life of a long-span cable-stayed bridge.

Definition of limit state of flexible pipe material in coiled tubing technology

Currently, the use of coiled tubing technologies has become widespread in drilling and oil production. The flexible pipes (FP) used in this technology undergo a complex of several impacts that accelerate the process of damage accumulation and thereby cause an accelerated process of seats of destruction formation, which often leads to accidents. Statistics show that the main reason for the destruction of the FP is the fatigue of the material loading and basically it is a cyclic bending according to the repeating stress cycle scheme. This loading scheme has a feature that is associated with the fact that tensile loads occur mainly in the convex zone of the pipe and compressive loads in the concave zone. Since the physical and mechanical properties of steels under stretch and compression are different, the process of damage and destruction accumulation during cyclic stretch and cyclic compression will have a different character. Information about the patterns of changes in the properties of the FP material allows to estimate the period of reaching the limit state and, thereby, prevent accidental destruction. In this regard, fatigue tests were carried out with a step-by-step measurement of magnetic characteristics that are structurally sensitive to the accumulation of fatigue damage. The determination of the stress amplitude for the FP fragment was determined by preliminary calculation in the ABAQUS PC. The test results showed that during cyclic stretch of the samples, the magnetic characteristics for assessing the limit state in the FP material were not informative. Notably in samples loaded with cyclic compression, the results of magnetic characteristics measuring (the resulting intensity and the gradient of the intensity of the constant magnetic field) showed sensitivity to the onset of the limit state. Based on the conducted studies, it is proposed to control the limit state of FP in the concave zone, where compressive loads mainly occur. These measurements allow us to estimate the value of the residual life of the FP material and to put this object out of operation in a timely manner, preventing accidental destruction.

Development of accelerated comparative assessment of contact fatigue strength based on the analysis of acoustic emission of friction units

The article presents the results of theoretical and experimental research of acoustic emission of friction units during rolling-sliding friction contact. The purpose of this study is the development of a method of accelerated assessment of contact fatigue strength with the application of acoustic emission during friction contact. The application of acoustic emission method reveals periods of energy state of the material: the activation, the damage accumulation, the transition to the initial fatigue damage. Pulse loading up to the maximum possible value was used for activation of damage accumulation process on the friction surfaces. Specific destructive energy for one load cycle was used as the fatigue strength assessment criterion. The developed technique allows to quantify the fatigue strength in analogy with the methods of such evaluation with the help of fatigue machines for testing at cyclic loads.

Mechanical compression characteristics of rapeseed based on continuous damage theory

In the process of mechanised sowing and harvesting, the damage and fragmentation of rapeseed are often caused by multiple contacts. The expansion of micro-defects and the accumulation of fusion damage in rapeseed can lead to fragmentation. To explore the law of mechanical damage of rapeseed, an elastoplastic model was established by Hertz contact mechanics. Combined with the continuous damage theory, the evolution equation of compression damage was established, and the accumulation method of compression damage was clarified. Three kinds of commercial seeds were taken as the experiment material. A single compression crushing test was carried out to verify the correctness of the elastoplastic model but multiple compression crushing tests were carried out to explore the damage accumulation process and method. The results show that the elastoplastic model can better fit the relationship between force and deformation during compression. The critical damage deformation δ d is equal to critical elastoplastic deformation δ s . When the deformation is more significant than 15 ± 2% of the diameter, the plastic deformation of rapeseed occurs. When the deformation is < δ d , the rapeseed will not be broken during the 30 cycles of equal displacement compression. When the deformation is > δ d , the damage leads to the decrease of the effective elastic modulus. With the increase of the compression deformation, the damage to the rapeseed intensified, resulting in the rapeseed being more easily broken. The research can provide a theoretical basis for designing structure and parameters in mechanised sowing and harvesting for rape. • An elastoplastic model for rapeseed was established by Hertz contact mechanics. • The evolution equation of compression damage for rapeseed was established. • The accumulation method of compression damage was clarified. • The damage leads to the decrease of the effective elastic modulus of rapeseed.

Stability of Postcritical Deformation of CFRP under Static ±45° Tension with Vibrations.

The paper presents an experimental study on regularities of postcritical deformation of carbon-fiber-reinforced plastic (CFRP) under static ±45° tension. The employed test method is based on ASTM D3518. Displacement and strain fields were identified by a digital image correlation method (DIC) using a VIC-3D contactless optical video system. Acoustic emission signals were obtained using an AMSY-6 system. The surface analysis of samples was carried out using a CarlZeiss SteREO Discovery. V12 optical stereomicroscope and a DinoLite microscope. Three experimental test types were considered: active loading, deformation with unloadings, and tension under additional torsion vibrations with various amplitudes. Loading diagrams were constructed; they showed a number of stages in the damage accumulation process. It was analyzed how heterogeneous strain fields develop; a neck development during softening process was observed. It was noted that the loading system rigidity influences the failure moment. The research considered various shear strain calculation methods using a "virtual extensometer" instrument. Composite mechanical properties were obtained. A shear modulus reduction during a plastic strain increase was revealed. The acoustic emission signals were analyzed; three characteristic frequency bands were observed. Most of the contribution to cumulative energy was made by matrix cracking. A reduction of the number of AE signals associated with the violation of adhesion between the fibers and the matrix during postcritical deformation was observed. The research identified basic surface defects. An appearance of the defects corresponds with their identification by the AE system. It was revealed that the presence of additional torsion vibration leads to an increase in the softening stage length. It was concluded that due regard for the postcritical deformation stage and the loading system rigidity is reasonable during the structure strength analysis.

Evaluation of the influence of preliminary low-velocity impacts on the residual fatigue life of CFRP composites

PurposeThe main purpose of this study was to evaluate the mechanical behaviour of layered fibrous carbon-fibre reinforced plastic (CFRP) under complex low-speed bending and impact loads and subsequent cyclic tensile loads.Design/methodology/approachA comprehensive approach was adopted to study the damage accumulation processes using state-of-the-art testing and diagnostic equipment. In the course of the study, a microstructure analysis of damages caused by a transverse impact and cyclic tension was performed.FindingsA dependence of residual fatigue life of the studied composite material on the intensity of the preliminary impact bending was established. Temperature field distribution fields on the surface of the sample during tests were shown. Data on damage accumulation processes were presented, which were obtained during the registration of acoustic emission signals.Originality/valueA connection was established between changes of registered acoustic response signals and thermal imaging camera data, which was supported by the results of an experimental study. The results of the comprehensive approach showed a qualitative correlation.

Fatigue damage development of grouted connection under varying cyclic loading

• Axial fatigue test of grouted connection under variable load range and sequencing. • Concrete damage plasticity-based model parameters used for numerical simulation. • Damage accumulation rate increased after sudden high load. • Load sequencing affects damage accumulation rate. • The damage accumulation of the real sized model was similar to the experimental model. The jacket structures of offshore wind turbines connect the foundation piles through a grout annulus. The grouted connections of the jacket structures are predominantly under the action of low-range fluctuating axial fatigue loads. However, they are sporadically subject to sudden large loads. The process of recurrent loading of the connection can lead to lose of capacity due to the gradual grout damage. Therefore, it is essential to study the damage accumulation process under variable fatigue loading. The cyclic compression tests of grouted connection scale model were performed and the influence of load-range, loading-sequence, and sudden large load on the fatigue damage accumulation was studied. The finite element models of experimental specimens and actual sized model were numerically simulated. An initial constant low load range yielded constant value of damage index and a sudden large load applied caused damage acceleration of the grout, which enhanced the development of damage under the subsequent low-range cyclic load. The larger load range prior to smaller load range created greater damage accumulation and reduced the residual vertical bearing capacity of the connection. The work offers a numerical basis for damage assessment of grouted connections of offshore wind turbines under variable axial fatigue load using the scalar damage degradation parameter in Abaqus finite element software.

Estimation of remaining fatigue life with an energy-based model considering the effects of loading sequence and load interaction

Accurate estimation of remaining fatigue life is crucial to assess the structural durability and reliability of engineering components. For this purpose, an energy-based model is proposed in this paper for modeling the process of fatigue damage accumulation under multistep loading. To account for the effects of loading sequence and load interaction, two parameters, a concept of normalized fatigue driving energy (NFDE) and a load interaction factor, are introduced in the model. The former is based on variable energy-life curves and the latter is formulized as an exponential function of the loading intensity ratio and the number of loading cycles. The implementation procedure of such model only requires the loading information and materials’ basic fatigue properties. Moreover, extensive experimental results of six metallic materials under two-, four- and eight-step loadings with different loading sequences are employed for model comparative study. The results indicate that, compared with several existing damage models, the proposed model can provide better remaining fatigue life estimations under multistep loading.

Study of Radiation Damage Processes Caused by Hydrogen Embrittlement in Lithium Ceramics under High-Temperature Irradiation

The aim of this work is to study the hydrogenation processes in lithium-containing ceramics under high-temperature irradiation. Irradiation was carried out with protons with an energy of 1 MeV and fluences of 1015–1017 ion/cm2 at irradiation temperatures of 300–1000 K. The choice of irradiation conditions is due to the possibility of simulation of the radiation damage accumulation processes in the near-surface layer of Li2TiO3 ceramics, as well as establishing the dependences of changes in structural parameters during temperature heating of samples during irradiation. It has been established that at irradiation fluences of 1015–1016 ion/cm2, the formation of dislocation defects is observed, the density of which has a pronounced dependence on the irradiation temperature. At irradiation fluence above 5 × 1016 ion/cm2, an increase in the crystal structure deformation is observed, due to swelling processes as a result of implanted hydrogen accumulation in the near-surface layer structure. At the same time, an increase in the irradiation temperature leads to a decrease in the swelling value, which is due to the accelerated migration of implanted hydrogen in the near-surface layer and its release through the existing pores. Results of mechanical tests showed that the swelling of the crystal structure and its deformation leads to embrittlement and a partial decrease in the strength of the near-surface layer. The obtained research results will further allow us to evaluate the resistance of lithium ceramics to the processes of hydrogenation and destruction as a result of the formation of gas-filled cavities in the structure of the near-surface layer.