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Ultrasonic cutting of an aramid paper honeycomb was studied using a simulation approach, which is quite instrumental for research of its mechanism and optimization of process parameters. The constitutive material model was constructed based on the mechanical properties of orthogonal isotropic aramid paper and the shear fracture model was built to describe the failure mode of a honeycomb during ultrasonic cutting to substantiate the reliability of simulation results. Simulation and full-scale triangular blade cutting experiments were comparatively evaluated. With an appropriate choice of the parameters, the deformation damage of the honeycomb material in simulation cutting does basically coincide with the experiment. A maximum error for the average cutting force is only 5.42%. The above results corroborate the accuracy of the model. [ABSTRACT FROM AUTHOR]

This paper examines the potential of using additive manufacturing (AM) technology to create nature-inspired designs with decreased stress concentration factors, which are typically the source of fatigue damage. AM has advantages over conventional manufacturing processes, allowing for creation of complex and optimized geometries. Based on a real case study, this paper evaluates the possibility of bio-inspired optimization of a connection between a tubular profile and a steel plate through AM technology. The results reveal a significant decrease in the stress concentration factor for the optimized bio-inspired AM solution compared to traditional construction solutions. [ABSTRACT FROM AUTHOR]

The paper analyzes the current state of the grain transportation freight car fleet. The results of the analysis show that grain rail cars have exhausted their initially assigned service life, which is set by the manufacturer, and have the same type of defects in load-bearing structures in the area of the riveted joint of the backstop of the car hitch to the girder beam. A 3D model of a grain rail car of a typical design was developed. The stress distribution near the holes of the riveted joint of the backstop of the car hitch with the girder beam under the simultaneous action of normative forces was calculated by the finite element method using the SolidWorks program according to the 3rd theory of strength by the established design modes I and III. Implementing the proposed improvement justified the need to conduct relevant research work. These works included the study of the places and causes of cracks, and their result became the basis for the proposed modernization of the car frame. [ABSTRACT FROM AUTHOR]

To date, most WWER-1000 nuclear power units in Ukraine have reached the end of their design life (30 years). In view of this, work is under way to extend the service life of critical equipment elements beyond the design life (to up to 60 years). In addition to reactor vessels, these critical elements include vessel internals (VI). One of the key approaches in such works is a predictive assessment of the structural integrity of VI structures using mathematical modeling of physical processes typical for power unit operation under intense radiation exposure of structural material. The service life prediction methodology constantly requires refining and taking into account more factors affecting structural integrity. The paper considers the kinetics of changes in the stress intensity factor for postulated cracks in the reflection shield of WWER-1000 VIs during long-term operation and at the time of reactor emergency during the rupture of primary coolant circuit pipelines with a nominal diameter of 100 to 850 mm in the most dangerous areas in terms of brittle fracture resistance. A significant impact of taking into account the residual stresses formed as a result of welding and heat treatment of the reflection shield during manufacturing on the results of calculating the brittle fracture resistance was revealed, which may affect the conservatism of assessment methods when justifying long-term operation. [ABSTRACT FROM AUTHOR]

In this paper, we propose an energy return optimization method for lightweight sandwich structure composite prostheses and study the performance of 3D-printed short fiber-reinforced composites in ESR prostheses. A commercial product is used as the original model, and a lightweight pyramid lattice sandwich structure is used to design the prosthesis. A gradient optimization method is designed to optimize the forefoot, hindfoot, and midfoot energy storage characteristics for multiple working cases based on the response surface approach. The response model of the pyramid lattice sandwich structure parameters and the energy return of the prosthesis was established. The designed variable stiffness pyramid lattice sandwich structure prosthesis has a higher energy storage efficiency in heel strike (17.55%), mid-stand (20.16%), and push-off conditions (55.93%), which is more adaptable to the prosthetic walking requirements. The research method of this paper successfully realized the application of composite lightweight dot matrix sandwich structures in prostheses, and the proposed optimization method has guiding significance for the optimization of prosthetic energy returns. [ABSTRACT FROM AUTHOR]

A carbon fiber-reinforced thermosetting plastic and stainless steel were joined by the fiber laser. The surface texture effect on the joint was investigated. The abrasive paper scratching is shown to form single directional striae on stainless steel with intermittent ridges. Laser texture processing creates uniformly distributed microdimples and ridges, which forms a rectangular cellular structure. This processing can improve the fluidity of molten polyphenylene sulfite during laser joining. Laser scanning on stainless steel results in the formation of fusion and heat-affected zones. In the heat-affected zone, lathy ferrite is located along the boundary, while in the fusion zone, ferrite forms the skeletal structure and separates austenite into a cellular structure. The surface texture modification can contribute to the adhesive strength between stainless steel and polyphenylene sulfite through on enlarged contact surface area by forming striae, microdimples, and ridges. As compared to the abrasive paper scratching, the stainless steel/plastic joint with laser texture processing exhibits a higher shear strength. [ABSTRACT FROM AUTHOR]

The alternate load path method for progressive collapse analysis ignores the cause and mechanism of member failure and its influence on the dynamic effect of the remaining structures. It must assume the location of member failure, which is unsuitable for grid structures with many members. In this paper, by using the double broken line follow-up strengthening model and the proposed VUMAT material constitutive model, taking the member instability and material failure as the member failure criteria and considering the geometric nonlinearity and material nonlinearity, the instantaneous member removal method for deleting the failure member in real time was proposed. On this basis, nonlinear dynamic analysis for a three-layer space truss was used to compare the effects of different member failure criteria on the structural responses, such as the member failure sequence and the occurrence time of the continuous structural collapse. The results show that when considering the instability of members, the initial member failure and the final progressive collapse occur earlier than when using the material failure criterion, which is more similar to the actual situation. Furthermore, the proposed VUMAT material constitutive model can apply to study the progressive collapse behavior of space truss structures. [ABSTRACT FROM AUTHOR]

This theoretical paper is devoted to a non-linear rheological model and its application in fracture analysis of a beam structure with an arbitrary number of longitudinal vertical cracks. The beam under consideration is a functionally graded material with viscoplastic behavior. The rheological model is structured by springs, dashpots, and a frictional slider that considers the plastic strains in the beam. The model is with two consecutive units. Solutions for the time-dependent strain energy release rate for each crack in the functionally graded beam structure under external mechanical loading are obtained using the rheological model. The J-integral is applied to control the solutions obtained. The solutions consider the viscoplastic behavior and the progressive variation of functionally graded material properties in the beam structure. It is shown that the solution derived in the present paper can be applied to examine the relation between the distribution of mechanical properties and the longitudinal fracture in functionally graded structural materials with viscoplastic behavior. [ABSTRACT FROM AUTHOR]

Firstly, this paper used a laser particle size analyzer to test the particle size distribution characteristics of four specific surface areas of phosphate slag powder particles. Then, it used the powder fractal theory to determine the fractal dimension of the different specific surface areas of the phosphate slag powder particle group. Finally, the effect of the fractal dimension of the phosphate slag powder particle group on the mechanical strength and activity index of the phosphate slag powder-cement cementitious system at 3 d, 28 d, and 180 d ages were studied. The results showed that the phosphate slag powder with different specific surface areas has self-similar fractal characteristics; the larger the specific surface area of phosphate slag powder, the higher the fractal dimension, and the fractal dimension of phosphate slag powder particle can characterize the properties of phosphate slag powder's fineness and particle gradation in the process of grinding and refining. The phosphorus slag powder particle fractal dimension, the mechanical strength, and activity index of the phosphorus slag powder-cement cementitious system have linear correlation characteristics; the larger the fractal dimension, the higher the mechanical strength and activity index of the cementitious system with phosphate slag powder. [ABSTRACT FROM AUTHOR]

In this paper, a low-power fully acoustic non-destructive testing (NDT) of glass fiber-reinforced composite plate has been presented. Input acoustic power in microwatt range was used for local defect resonance (LDR)-based delamination activation. Besides experimental results, numerical simulations were carried out via commercial ABAQUS platform. An oblique incident wave interaction with 3D composite plate was created, and the sound radiation pattern over the plate was studied with an air layer over the plate. In experiment, the sound was generated by a piezospeaker, while a MEMS microphone was used for reception over the plate. Moreover, a laser Doppler vibrometer was utilized for the LDR frequency and corresponding mode shape validation. Frequency spectrum, mode shape at LDR frequency, best wave impinging angle, efficiency, and sound directivity patterns were studied, with angles θ, ϕ = 10°, 30° being found to correspond to the best direction for sonic excitation. Moreover, fully acoustic system was found to be more efficient than partial acoustic system, i.e., that with contact excitation. The proposed method can be used for inspection of large structures taking advantage of the long-distance non-contact excitation. [ABSTRACT FROM AUTHOR]

This paper systematically analyzed and discussed the microstructure and mechanical properties of as-cast AZ61 magnesium alloy with rare-earth content of 1.0~4.0 wt.% by optical microscopy, SEM, EDS, and XRD. The results indicate that in addition to the obvious distribution of skeletal β-Mg17Al12 phase, a small amount of Mg32(Al, Zn)49 quasicrystal phase is distributed in as-cast AZ61 alloy. With the addition of rare-earth content, the skeletal β-Mg17Al12 phase dendrites in the as-cast AZ61 magnesium alloy matrix are decomposed obviously. The dendrite decomposition is more serious with increased Rare-earth content, and the quasicrystal Mg32(Al, Zn)49 disappears. When the rare-earth content is 1%Ce~2%Ce, the alloy mainly consists of needle-like, dot-like, or clustered Al4Ce and Al8Mn4Ce phases with a small amount of Al4La. When 2.8%Ce+1.2%Nd mixed rare-earth was added, the Al8Mn4Ce phase was not found in the alloy but mainly composed of Al3Nd and Al4Ce rare-earth phases. These rare-earth phases were radiative needle-like, willow leaf-like, rod-like, spot-like, layer-like, and a little irregular block. The as-cast AEZ641(2.8 wt.% Ce+1.2 wt.% Nd) magnesium alloy has the best comprehensive performance, and the yield strength is 2% higher than the as-cast AZ61 alloy. Its tensile strength, hardness, and elongation are similar to as-cast AZ61 alloy. The fracture mechanism of as-cast AZ61 + xRE is mainly a cleavage-type brittle fracture. [ABSTRACT FROM AUTHOR]

Due to critical vibration and excess weight in the frame structure of the automobile, the automobile acceleration effects are the primary problems. This paper describes the material selection based on its weight, vibration reduction, and increasing vehicle performance. The front cabins heavy-duty van frame was considered for this research work and designed according to the frame dimension. Generally, the frame is made of mild steel and replaced by high-strength extrusion magnesium alloy. The frame structures crash and impact analysis was investigated using nonlinear buckling and transient analysis. The stress, vibration and nonlinear buckling analysis was obtained under different loading conditions. The bending performance of the frame was analytically investigated and verified with the FEA code (ANSYS 15.0). [ABSTRACT FROM AUTHOR]

A friction stir joining technology was used in preparing a performance gradient aluminum alloy sheet through friction stirring. The sheet was treated by solution aging, and the metallographic structure and hardness of the sheet before and after heat treatment were analyzed. Results showed that the sheet with good hardness gradient distribution can be obtained by selecting appropriate process parameters. When the rotation speed of the stirring tool is 300 rpm, the feed speed of the stirring tool is 250 mm/min, the downward pressure of the stirring tool is 6.6 mm, the hardness distribution of the upper and lower surfaces and sections of the specimens with or without heat treatment improves, and the best gradient hardness distribution of the sections is obtained. The grains in the stirred region of the prepared gradient sheet obtained by each parameter are refined to a certain extent, especially after heat treatment. Grain changes are obvious, but the grains grow after heat treatment. The second phase precipitated after heat treatment is evenly distributed, and this is effect improves the hardness of the sheet. The aluminum alloy gradient material prepared in this paper can meet the requirements of the automobile industry and other molding plate performance requirements. It is also found that the friction stir joining technology can better prepare aluminum alloy gradient material, and the fabricated material has fewer defects than the continuous casting technology. [ABSTRACT FROM AUTHOR]

The mechanism of fracture propagation from the circular blast holes with two symmetrical cracks in rock blasting operations was investigated by the displacement discontinuity method. The stress intensity factors at the crack tips of the pre-existing cracks were numerically determined using the displacement variations near the crack tips. In this paper, the variation of the displacement discontinuities along pre-existing cracks emanating from blast holes are studied and compared using linear, quadratic, and cubic collocations. For the crack tip behavior, cubic collections are used, and also the special crack tip element is employed to reduce the singularity at the crack tips. The numerical results of the normalized stress intensity factor for linear, quadratic, and cubic collocations of the displacement discontinuities compared with the analytical results. These sets of results are compared with one another, and good agreements have been reached between them. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental study of the deformation properties of 10GN2MFA and 15Kh2MFA steels at different ratios of principal stresses under cyclic loading conditions. Applying the proposed phenomenological approach of an improved elastic-viscoplastic model allows one to qualitatively describe the effects of the influence of structure degradation under the action of temperature and force factors that accompany the operation of actual structural elements significantly affecting the regularities of deformation and damageability and the strength of structural materials under combined stress conditions. An evaluation of the variation rate in the homogeneity of the studied steels at different ratios of principal cyclic stresses under cyclic creep conditions is presented. Based on the experimental results, correlation dependences between the relative values of the homogeneity coefficient and the function of the deformation properties of the material and the type of stress state were obtained, which significantly simplifies the determination of the parameters characterizing the limiting state of the structural element. [ABSTRACT FROM AUTHOR]

In engineering practice, conservative approaches are used to assess the technical condition of pipelines with typical elements (branches, tees and adapters) using reference data on the mechanical properties of the metal in its original state. The use of such approaches to assess the technical condition without taking into account changes in the mechanical properties of the metal during the manufacturing process and long-term operation can lead to significant errors. As an example, this paper presents the results of experimental studies of the mechanical properties of the metal of the characteristic zones of typical pipeline elements and the steam generator housing. It is shown that the differences in the characteristics of resistance to the short-term static and cyclic loads of individual sections of typical pipeline elements are associated with the influence of technological and operational factors. It is recommended to use nondestructive testing methods for the rapid evaluation of differences in the structural state of the metal of different portions of the product, which determines its mechanical properties. [ABSTRACT FROM AUTHOR]

The paper considers the use of hydrogen as a component of the technological process to solve an applied problem - the control of material defects, which consisted of controlled fragmentation of steel under dynamic loading to facilitate the cracking of the metal volume. Medium-carbon pearlite-ferrite steel of steel 60 types under electrochemical hydrogenation is studied. The criterion parameter of the material state was the energy of impact loading by three-point bending of smooth beam specimens. By selecting the electrochemical hydrogenation modes in terms of intensity (current) and duration of the process, as well as the composition of the electrolyte, a significant reduction in the energy intensity of steel fracture was obtained, which correlates with the residual hydrogen concentration in the metal. Metallographic analysis of the surface of the specimens confirmed the hydrogenation effect on the initiation of defects, which can be used for controlled steel fragmentation. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on the static, microstructural and impact properties of concrete incorporating tire rubbers. Fine tire rubber (FR) and coarse tire rubber (CR) were used to replace fine and coarse aggregates, respectively, by 10 and 20% by volume. The single and combined effects of tire rubbers on the unit weight, mechanical properties (compressive strength, split tensile strength, flexural strength, and flexural toughness properties) and impact resistance of concrete were evaluated. Drop-weight test using concrete beams was conducted to evaluate the impact behavior of concrete. The microstructure of concrete was also investigated using SEM analysis. The results showed that incorporation of FR and CR reduced the unit weight, compressive strength, and flexural strength of concrete. Lower content of tire rubbers increased the split tensile strength of concrete, however higher content of tire rubbers resulted in its reduction. On the other hand, tire rubbers were found to remarkably enhance the energy absorption capacity, fracture energy and impact strength of concrete. SEM observations revealed that rubberized concretes had more porosity and weaker interfacial transition zone than normal concrete. In general, when FR and CR were used together, they showed an average static and impact performance compared to their single use. [ABSTRACT FROM AUTHOR]

Radar stealth was a remarkable technical feature of the fourth-generation fighter aircraft, the damage of the stealth coating would seriously affect the stealth performance of the aircraft. This paper focuses on the membrane treatment of coating in the process of stealth coating damage repair, the effect of laser cleaning process on the cleaning effect of stealth coating on the surface of aircraft metal construction was studied. The results show that laser pulse width has the greatest influence on the laser cleaning of stealth coating, so pulse width should be prioritized when selecting the process parameters. And during the process experiment, the relationship between the effect of laser cleaning and process parameters were respectively negative correlation with scanning speed, positive correlated first and then weakly correlation with laser power, weakly correlated first and then positive correlation with pulse width, positive correlation with scan number. Finally, the optimal laser cleaning process parameters for the stealth coating of 500 μm on the surface of the metal structures were obtained by comparing the experiments between the preferred and the solution groups. [ABSTRACT FROM AUTHOR]

The instrumented indentation method, based on the digital recording of the parameters of the entire process of continuous local deformation of the material by an indenter, provides more complete and accurate information about the material's behavior under load. Obtaining such information without compromising the integrity of a critical structure during operation increases its value. Therefore, more and more attention has recently been paid to portable installations and devices that use the instrumented indentation method. To date, no such equipment is manufactured in Ukraine. Therefore, there is a need to develop portable equipment for conducting such tests in the field under various modes of static and cyclic loading in the macro range of forces. The paper describes an updated portable installation PIIT-02M for determining the strength characteristics of structural elements in service by instrumented indentation, which was developed following the requirements of ISO 14577 and is intended for testing at the macro level. The system of fastening the portable installation on the test object was updated from mechanical (hooks and chains) to electromagnetic. This made it possible to conduct tests on pipes and flat surfaces, including sheet materials and structures made of them, significantly increasing the test efficiency and expanding the range of applications. Comparative tests on a 12 mm thick structural carbon 20 steel plate using the previous mechanical fastening system and the new electromagnetic one showed that the indentation diagrams obtained overlap well. Based on the results of tests of high-strength steels, the portable installation PIIT-02M allows one under both laboratory and operating conditions to record the process of indentation of the indenter into specimens of structural materials with high accuracy and, accordingly, to determine their mechanical characteristics by instrumented indentation. [ABSTRACT FROM AUTHOR]

Along with the classical finite element method (FEM), other calculation methods for assessing crack resistance characteristics are currently being actively developed. This is due to the existing shortcomings of the FEM caused by the dependence of the calculation results on the density of the finite element mesh. One of the promising methods being developed in world practice is the extended finite element method (XFEM), which allows obtaining satisfactory calculation results while simplifying the crack modeling procedure and saving calculation time. In this paper, three problems are numerically modeled using the classical FEM and XFEM methods: calculation of a disc crack in a cube under uniaxial tension, calculation of the off-center tension of a compact CT specimen, and calculation of a cylindrical part of an NPP reactor vessel with a semi-elliptical crack under thermal shock. The obtained results showed that the extended finite element method gives sufficiently accurate results compared to analytical solutions and the classical FEM. At the same time, using the XFEM method does not require considering the singularity of stresses at the crack tip when building an FE model. Therefore, the minimum size of the FE can be increased by almost five times while maintaining the accuracy of the results. This greatly simplifies the procedure for constructing the FE mesh, reduces the total number of FEs in the model, and saves computational time. Thus, the XFEM method can be used to calculate the crack resistance characteristics and improve the efficiency of assessing the resistance to brittle fracture of structural elements. [ABSTRACT FROM AUTHOR]

The paper presents analytical and numerical methods based on finite element modeling for determining vibrodiagnostic indicators of the presence of a transverse edge crack closing in a cantilever composite beam made of orthotropic material. The results of studies of the effect of its presence on the change in the main vibration frequency and on the ratio of the amplitudes of the dominant harmonics at the main, superharmonic order 1/2, and subharmonic order 2 resonances are presented. It has been shown that for a composite beam reinforced in the bending plane with unidirectional fibers with their laying angles relative to the axis of 0...40°, it is advisable to use the change in the natural vibration frequency as a vibration diagnostic indicator, and for larger angles, the ratio of the amplitudes of the dominant harmonics at super- and subharmonic resonances may be of practical importance. [ABSTRACT FROM AUTHOR]

Welding technology is widely used in the steel structure forming process. After welding, there is uneven residual deformation in the structure, resulting in welding residual stress. In this paper, the damage process of beam-column joints in steel frames under ultra-low cycle fatigue loading was simulated by ABAQUS software. The crack initiation position of the joints was obtained. On this basis, the influence of welding residual stress on the development of tensile and bending fatigue damage of beam-column joints in steel frames was analyzed. In parallel, the effect of welding residual stress on the fatigue damage process of joints with different loading modes and different beam flange widths was discussed. The results show that during ultra-low cycle tensile and bending fatigue, cracks are both initiated at the welding holes of the beam flange, but the cycle number required for crack initiation is different, and the cycle number to failure of bending fatigue is greater. The residual stress can accelerate crack initiation and advance approximately two cycles. For bending fatigue damage, the crack first originates from the flange in tension first, and the average cycle number to failure of the flange is 12.85% more than that of the other flange. With the flange width decreasing from 150 to 130 mm, the cycle number to failure affected by residual stress rises from 5.30 to 13.56%. With the increase in cycle number, the damage development of a single cycle is more affected by the residual stress, the increasing trend of the fracture index remains unchanged, and the growth rate becomes faster. [ABSTRACT FROM AUTHOR]

This paper investigated the effect of cavity cleaning methods on the bond strength of adhesive systems to dentin after removing zinc-oxide eugenol (ZOE) temporary material. Coronal parts of 96 extracted third molar teeth were removed, and occlusal access cavities were prepared. After root canal treatment, cavities were filled with ZOE and stored in distilled water for seven days at 37°C. After ZOE was removed, teeth were randomly divided into three groups according to cavity cleaning methods (control, 2% chlorhexidine, and ethanol), and five subgroups (3-step total-etch, 2-step self-etch, 1-step self-etch, universal adhesive, and chlorhexidine containing universal adhesive). After restoration with composite resin, the specimens were sectioned into 1 mm2 surface area beams. A microtensile bond strength (μTBS) test was performed. Failure modes were determined under a stereomicroscope and analyzed with a scanning electron microscope. The highest μTBS was observed in chlorhexidine-containing universal adhesive after applying ethanol for 30 s. Ethanol application for 30 s created cleaner dentin surfaces and could increase the adhesive penetration by removing the ZOE residues better than the control and 2% chlorhexidine application for 30 s. [ABSTRACT FROM AUTHOR]

Field investigations of earthquake-stricken areas have shown that eccentric structures usually suffer more severe seismic damage than symmetric structures due to translational-torsional coupling. While most studies have focused on the torsional response of single-layer or unidirectional eccentric structures, this paper presents a whole-process parametric analysis of the translational-torsional coupling effect of the multilayer bidirectional eccentric frame structure. Next, a nonlinear static analysis is performed via a self-compiled MATLAB program, revealing a general law for the variation in the natural frequency of the multilayer eccentric frame structure in different layers during its evolution from the elastic to the elastoplastic stage. This process is subdivided into three distinct analytic stages. The parametric analysis is also performed for the translational-torsional displacement ratio varying with the noncoupled torsional-translational frequency ratio (Ω) and the bidirectional eccentricity (bx, by) throughout the three stages. The analysis shows that the translational-torsional coupling effect of the bidirectional eccentric structure was most intense at Ω = 1.1. This is a very adverse situation that may occur in the torsion-resistant design of the structure and deserves extra attention. The translational-torsional coupling effect is aggravated along the load (x) direction as it increases and is unaffected by bx, Ω, or the elastoplastic development process. The degree of influence of bx on the translational-torsional coupling effect depends on which particular layer of the structure is under consideration and the elastoplastic development process. As elastoplastic development proceeds, the translational motion of the structure along the load direction finally predominates. Meanwhile, the translational-torsional coupling effect along the load direction decreases dramatically. [ABSTRACT FROM AUTHOR]

The paper deals with the 3D printing process that is compatible with electrodynamic processing (EDP) of the printed layer in order to increase the density of the latter. Based on mathematical modeling, the influence of the impactor shape for EDP on the stress-strain state of the AMg6 aluminum alloy layer was studied. The formation of residual compressive stresses in the EDP zone was taken as a compaction criterion. The distribution of values along the thickness of the plate of the main parameters and components of the stress-strain state, in particular, the plastic deformation and stress zone dimensions, the depth and width of the contact interaction zone in the metal layer interacting with an impactor roller moving normal to the layer at speeds of 1, 5, and 10 m/s, was determined. The cylindrical impactor with a rounded end surface usage instead a straight quadrangular prism with a rounded side surface formed a higher-density layer, characterized by generation of compressive stresses up to the yield strength of the AMg6 alloy. This helps optimize the structure of the printed metal and increase its durability by forming compressive stress fields in the electrodynamic compaction zone. [ABSTRACT FROM AUTHOR]

When preparing tungsten-cobalt gradient alloy under nitriding conditions, TiC becomes a very important additive because it can effectively promote the formation of gradient structure. However, doping TiC often causes a large number of defects such as holes, cracks, and impurity segregation in the tungsten-cobalt cemented carbide matrix. The paper is mainly studied the improvement of microstructure and mechanical properties of Ti-containing cemented carbide by doping appropriate amount of NbC or VC. The results show that: doping with NbC or VC can refine the grains of the hard phase, effectively control the microstructure and mechanical properties of the alloy, significantly improve its compactness, and increase the hardness and transverse fracture strength of the alloy. However, the fracture toughness is reduced. When the doping amount is less than 0.6% (mass fraction), VC effects on improving the hardness and transverse fracture strength more obviously than NbC; when the doping amount is equal to 0.6% (mass fraction), the difference between VC and NbC in improving the transverse rupture strength is not significant. Comparing the two additive contents studied in this paper, when the VC content is 0.6% (mass fraction), the performance of cemented carbide is better, with a hardness of 1836 HV30kgf, a fracture toughness of 8.85 MPa·m1/2, and a transverse fracture strength of 1888 MPa. [ABSTRACT FROM AUTHOR]

In order to predict the temperature, humidity and deformation of the 3D gel-printing metal laminated green body during the drying process. This paper presents a mathematical model of solving the coupled temperature, moisture, and stress-strain fields during the drying process. This model was established on the Luikov's irreversible thermodynamics and material mechanics. It was numerically solved based on the discrete difference method, and it was implemented into numerical simulations through a combination of sequence and direct coupling method. The results have shown that, for the temperature field, green body temperature field approached to be steady in a short time during drying. For the moisture field, moisture migration exhibited between materials with different initial moisture contents. While for the stress-strain fields, obvious tensile stress state was experienced on the edges of green body longitudinal sides. The research carried out in this paper contributes to provide a comprehensive guide of the process planning of drying process of green body. [ABSTRACT FROM AUTHOR]

In this paper, the numerical simulation of the temperature field and welding angular distortion of a 6mm-thick 5A06 aluminum alloy plate was performed by application of the ABAQUS 2018 finite element analysis software. A 3D thermo-mechanical model of the plate under study with account of heat transfer in the arc motion direction was established. The temperature field distribution and welding-induced angular distortion in the welded structure obtained by the simulation were analyzed to minimize the production cost and improve the production efficiency. By analyzing the magnitude and distribution of residual stresses in the welded structure, selecting a reasonable welding process, and optimizing the design to reduce and control the residual stress, the aluminum alloy welded structure can be effectively manufactured. [ABSTRACT FROM AUTHOR]

As the two typical structural paper packaging materials, corrugated fiberboard and honeycomb paperboard occupy an important position in the field of logistics packaging. Up to now, numerous studies were focused on the properties of the above sandwich paperboards. However, the issue of their edgewise compressive strength has reached no consensus yet. The objective of this study is to investigate the edge effect and the influence on edgewise compressive strength of the two sandwich paperboards by experimental and numerical simulation methods. Firstly, the standard size specimens of the two sandwich paperboards were made based on the machining direction (MD) and cross-machining direction (CD), and the edgewise compressive strength experiments were carried out. Secondly, the finite element models of corrugated fiberboard and honeycomb paperboard were constructed using the same material, comprehensive weight and thickness, while the numerical assessment on edgewise compressive strength of CD and MD of the models were analyzed, respectively. Finally, measures to restrain the edge effect were taken, and the edge enhancement finite element models of the two paperboards were eleborated. The buckling analysis was carried out based on the numerical method. The results obtained suggest that the edge effect is one of the major factors controlling the edgewise compression strength of corrugated fiberboard and honeycomb paperboard. [ABSTRACT FROM AUTHOR]

Accelerated life test experiments aim to generate lifetime data in a short time for the further statistical analysis, and are very useful when the units under experiment are highly reliable. Statistical analysis for lifetime data observed from accelerating life testing in presence of some censoring becomes a challenging task. In this paper, we consider lognormal distribution under a simple step-stress model in the presence of hybrid censoring. We assume that the lifetimes follow the cumulative exposure model, and first obtain maximum likelihood estimates and their associated interval estimates using various methods. We then compute Bayes estimates and associated highest posterior interval estimates under squared error loss function. To observe the effectiveness of the proposed methods under the different situations, we conduct a simulation study. [ABSTRACT FROM AUTHOR]

Structural sheet metal materials are widely used in machine, aircraft, and rocketry building. Their strength under static tension (compression) is the primary characteristic and attribute in selecting materials for design developments. However, it is necessary to prioritize tension–compression fatigue tests for correct strength comparison under static and variable loads. The methodological difficulties associated with the need for the excitation of longitudinal vibrations in thin strip specimens with low stiffness limit the possibility of studying their fatigue strength under cyclic uniaxial tension– compression. The paper proposes a procedure for experimentally determining the fatigue strength of sheet materials under cyclic tension–compression under high-frequency loading. A special advantage of the procedure is the ability to ensure the proper stiffness of specimens without predeformation, which distorts the true experimental data inherent in the undeformed material. An algorithm was developed, and corresponding calculations were performed for a vibrating system, of which the specimen is a constituent part. The practical calculations are based on solving the problem of free longitudinal vibrations of a system of three dissimilar rods joined together at the free ends by common masses. Formulas for determining the rupture stress in specimens were obtained. Test trials of specimens of D16T and VT1-0 alloys confirmed the practical efficiency of the procedure. A resonant vibrating system was used, which was manufactured based on the results of the above theoretical calculations. In the design of this system, specimens with a cross-section of (0.5×5)×10–3 m had an active length of 48.2×10–3 m. The fatigue failure of specimens that occurred in the computational zone was controlled by the magnitude of the working stresses and the time of their occurrence. For example, a specimen of D16T alloy failed at a stress of 220 ×106 Pa after 8 ×106 loading cycles. [ABSTRACT FROM AUTHOR]

Calculations of the reliability of mine workings' support usually imply multifactorial problems that can be solved using the risk theory in combination with the expert method of pairwise comparisons. The paper presents a methodology for such calculations on the example of the protection of sectional workings in coal mines. The necessity of improving the methodology for calculating the displacement of the mine workings contour in the area of influence of the cleaning operations by taking into account the coefficient of influence of the mine support equipment (MPE) on its stability is substantiated. This work aims to increase the reliability of mine workings' support by risk-oriented substantiation of the choice of the type of protection means for sectional workings of coal mines during the development of an adjacent excavation column in various geological conditions. Technological schemes for the construction of modern types of MPE are proposed. Combining the risk theory with the matrix method of pairwise comparisons made it possible to calculate the risk Ri of deformation of the working faces and to obtain a qualitative assessment of the rating Ti of different types of MPE depending on the categories of roof collapse An and the strength of the floor rocks f. The criteria for comparing different types of MPE is their compliance with the utility function: at rational costs for the construction of MPE, the risks of roof and face displacements should be minimal. The proportion of negative consequences from failure to meet the initial requirements is as follows: the cost of MPE construction is 0.13, the risk of displacement of the working face roof is 0.53, and the risk of floor displacement is 0.33. A new formula for calculating the coefficient Ko of the influence of the type of underground protection on the displacement of the working faces is proposed, which takes into account the risk of deformation of the working face, the power and the inclination angle of the coal seam to the horizon, and the design parameters of the underground protection – its width and location relative to the working face. [ABSTRACT FROM AUTHOR]

This paper provides a method to predict the long-term creep behavior of continuous glass fiber-reinforced polypropylene composites (CGFRPP). The finite element method was used in this study, which was based on short-term experiments. For these calculations, a viscoelastic constitutive equation named the Burgers model was introduced to describe the creep behavior of pure polypropylene (PP) resin. The suitability of the Burgers model for the PP resin was investigated by performing short-term creep experiments under various stress conditions. The stress-dependent Burgers model was, thereafter, proposed by the calibration of elastic stiffness and viscosity parameters in nonlinearity. This nonlinear model was finally incorporated into a representative volume elements (RVE) model to predict the long-term creep behavior of CGFRPP unidirectional (UD) tape. It was found that the simulation results agreed with experiments when using the nonlinear Burgers model. The creep mechanism of the UD tape was also analyzed microscopically with the RVE model, and the redistribution of stress in the fiber and matrix was discussed. [ABSTRACT FROM AUTHOR]

Establishing a quantitative prediction model for the SCC crack growth rate of dissimilar metal welded joints at the safe end is very important for the safety evaluation of nuclear power structures. However, the SCC growth process is closely related to crack tip creep. In this paper, uniaxial tensile creep experiments under different stress are carried out on nickel base alloy 600, and the constitutive creep equation of nickel base alloy 600 is established. At the same time, the SCC crack tip creep field is analyzed using finite element software, and the effects of crack tip creep variables, creep rates, and material creep properties on the crack tip field are analyzed. Results show that nickel base alloy 600 occurs creep under high stress, and the creep rate in the crack tip region decreases with the crack inclination angle and the distance from the crack tip. The peak values of creep and creep rate appear directly in front of the crack propagation direction. Research results lay a foundation for establishing a quantitative prediction model of SCC. [ABSTRACT FROM AUTHOR]

The paper deals with the dynamics of asymmetric three-layer hemispherical shells with the discretely symmetric lightweight, rib-reinforced filler under pulsed loads. Since the distances between the ribs are much larger than the dimensions of the rib cross-sections, the theory of independent static and kinematic hypotheses for each layer is applied. In asymmetric shells, the load-bearing layers are made of different materials and have various thicknesses. The equations of motion of asymmetric three-layer spherical shells and natural boundary conditions are obtained using the Hamilton– Ostrogradsky variational principle for the Timoshenko-type shell and rod theory model. This makes it possible to develop an adequate finite element model for asymmetric three-layer shells composed of several materials and obtain numerical results on the dynamic behavior of an asymmetric three-layer elastic structure using the finite element method. The influence of physical and mechanical parameters of asymmetric layers of hemispherical shells on the stress-strain state under axisymmetric internal pulse loading is investigated. New mechanical effects are revealed. [ABSTRACT FROM AUTHOR]

The paper presents the results of a computational assessment of the shape change of the WWER-1000 reactor core baffle using modern approaches to modeling the processes of radiation swelling, radiation creep, and subcritical damage of irradiated metal by the mechanism of ductile fracture. To simulate radiation effects, mathematical models are used that consider the influence of the stress state and accumulated irreversible deformation on the swelling and creep of austenitic steels exposed to neutron irradiation and elevated temperature. The increased volume concentration of ductile fracture pores in the irradiated metal is considered using the modified Huang equation and the proposed equation derived from Kachanov's solution for a spherical cavity in an unbounded elastic-plastic medium. The determination of the stress-strain state of the WWER-1000 reactor cavity and the inner vessel shaft is based on solving a nonlinear boundary value problem of thermomechanics, which allows describing the kinetics of the coupled processes of elastic-plastic deformation, radiation swelling, radiation creep, contact interaction, and subcritical damage of irradiated metal depending on the accumulated dose of neutron irradiation. The computational analysis is based on a mixed finite element method scheme that provides a continuous approximation for both displacements and stresses and strains, which makes it possible to determine the shape change of the shielding with a high degree of accuracy. The calculation was performed in a two-dimensional formulation for the cross-section of the shielding with the maximum height of the damaging dose and irradiation temperature under the condition of generalized plane deformation. The calculation results were obtained using the median parameters of the temperature-dose dependence of free swelling of austenitic steel 08Kh18N10T. Based on the calculated data, the influence of radiation effects and metal damage according to the ductile fracture models on determining the shape change of the WWER-1000 reactor baffle under conditions of long-term operation was analyzed. [ABSTRACT FROM AUTHOR]

Materials science and engineering is one of the hot research topics in the world, among which mechanical properties of materials play a critical role in application of the new materials. Based on this, a special session Mechanical Properties of Materials was held within the 2nd Global Conference on Materials Science and Engineering, Nov. 20-22, 2013. This special issue contains a selection of twenty scientific papers, which are focused on the structure, mechanical properties, and strength of materials. In this review, the selected papers from the special session are summarized. [ABSTRACT FROM AUTHOR]

This paper evaluates and modifies the direct strength method (DSM) in AS/NZS 4600:2018 for cold- formed channel purlins based on the nonlinear analysis of Strand7 software. Initially, the original DSM curves from the THIN-WALL program are investigated for each buckling mode. Then the nonlinear analysis is performed using the finite element method (FEM). Next, the accuracy and reliability of the original and modified DSM curves are examined and analyzed based on the FEM results. In analyzing the results, the differences, mean and standard deviation between DSM and FEM results are compared. The percentage error ε is reasonable with the width-to-thickness ratios of 40 ≤ b/t ≤ 75, while in the distortional buckling mode, the acceptable range of the width-to-thickness ratio would be 32 ≤ b/t ≤ 63. Most sections have reasonable error values for different slenderness ratios λl (or λd). The results show that the modified DSM results are more accurate and reliable than the original ones, and the dispersion and calculation error of the test data will be smaller after the modification. However, the study's limitations would be the interference of the buckling modes and the sample size. The results of this research will provide structural engineers with a more comprehensive analysis of design methods and can be used as a reference for engineering design. [ABSTRACT FROM AUTHOR]

The paper proposes a method for determining diagrams of the limiting cycle amplitudes of welded joints with steady-state residual tensile stresses based on the test results of small-sized specimens and presents the corresponding calculation dependencies. This technique is an express method for estimating the fatigue resistance characteristics of welded joints if full-scale tests are not feasible. The analysis of literature data for various types of welded joints shows a good fit of the experimental and calculated values of the endurance limits of welded joints of low-carbon steels with low-alloy, low-strength steels. It is shown that the inclined section of the diagram with steady-state residual stresses is shifted in parallel relative to the diagram of cycle amplitudes of welded specimens without residual stresses. It has been established that the diagrams of the limiting cycle amplitudes of welded joints with different values of the steady-state residual stresses end on a line where each point at different average cycle stresses corresponds to the minimum limiting cycle amplitude of the welded joint with its particular value of the ultimate steady-state residual stress, which ensures the realization of the ultimate stress cycle. With the same value of the steady-state residual stress, the endurance limit of welded joints decreases with an increase in the yield strength. It is shown that low values of steady- state residual stresses result in nearly the same endurance limit reduction of butt welded joints of steels of different strengths. In contrast, their higher values aggravate the endurance limit deterioration of steels with higher mechanical characteristics. [ABSTRACT FROM AUTHOR]

In the process of use and manufacture, carbon fiber foam sandwich structures were often damaged by low-energy impact, resulting in performance degradation. Therefore, it was necessary to study the damage caused by the low-speed impact of composite sandwich structures. Based on the Hashin failure criterion, this paper established an equivalent finite element model of carbon fiber foam sandwich panels under low-velocity impact. The model was used to simulate the damage of the foam sandwich panel with [±45°/±45°/(core)/±45°/±45°] ply structure under the impact energy of 10.58, 21.17, 31.75, and 42.34 J. The simulation results of impact damage depth were compared with the experimental results. The error was less than 10%, which proved the rationality of the impact equivalent model. The model was used to predict and analyze the damage of foam sandwich panels with [±45°/(core)/±45°], [±45°/ (0°, 90°)/(core)/±45°], and [±45°/(0°, 90°)(core)/(0°, 90°)/±45°] ply structures under 21.17J impact energy. The low energy impact resistance was analyzed by comparing and analyzing the damage situation, impact force response time, and impact velocity response time. The results showed that increasing the number of ply layers [±45°] can reduce the impact damage degree and improve the bearing capacity of sandwich panels. [ABSTRACT FROM AUTHOR]

The paper analyzes the peculiarities of forming honeycomb structures by additive methods (in particular, from plastic filament (Fused Deposition Method, FDM) and shows that the engineering application of products with honeycomb structures should take into account the peculiarities of structural damage development under the influence of working loads. For typified products in the form of closed multilayer shells (tanks for various technological purposes), these are thermobaric effects that lead to a loss of the long-term strength of the product and to the development of damages on the initial defects. It is proposed to divide the latter into three groups: defects in the form of cavities of various volumes and shapes, as well as contact patch defects at the adhesion boundary of the laid-down layers under the conditions of stable technological process; defects formed by random factors of a technological nature; defects arising from heterogeneities and initial differences in the material used (plastic filament). It is concluded that the loss of the bearing capacity of shells made of structural plastics (except for highly elastic ones) can be described by the development of cracks in the interlayer areas of the product in accordance with Griffiths' theory. It is in these areas that the presence of defects is greatest. Since there is a significant difference between the mechanical properties of plastic filament and the product made by extrusion, it is proposed to use the equivalent properties of the components of a cellular system in the form of a three-layer connected shell in analyzing the stress-strain state of the product model. [ABSTRACT FROM AUTHOR]

Recent studies have shown that nozzle zones are one of the most dangerous elements of the reactor vessel. High stresses in such nodes can lead to the appearance of angular cracks. At the same time, the issue of choosing the critical dimensions and direction of crack location from the point of view of calculations for resistance to brittle fracture remains open. The paper presents the results of numerical modeling of the stress-strain state of the nozzle zone of the reactor vessel by the classical finite element method (FEM) and the extended finite element method (XFEM) using the submodeling technique. The results of numerical modeling by the classical FEM for the mode of hydraulic testing of the reactor vessel pressure vessel nozzle zone with three types of cracks are presented: surface, subweld, and a crack with 1 mm penetration into the weld. For twelve types of cracks with variations in their size and direction of location in the reactor vessel pressure vessel nozzle zone, the results of calculations of resistance to brittle fracture by the XFEM method for one of the characteristic modes of thermal shock are presented. The calculation results proved that axial cracks are more dangerous than circular cracks of the same dimensions. Cracks with a semi-axis ratios a/c = 0.3 and a/c = 0.7 are more dangerous for the axial and circumferential directions, respectively. At the same time, cracks with a/c = 0.3 are more sensitive to the direction of location than cracks with a/c = 0.7. It was shown that the use of the XFEM method makes it possible to conduct a rapid assessment of the resistance to brittle fracture with the possibility of varying the shape, size, and location of the crack, which allows one to effectively determine its critical size and the most dangerous location in the structural element. [ABSTRACT FROM AUTHOR]

This paper proposed a modeling method of the thermo-fluid-solid coupling simulation for the hot water pipeline with the insulation layer outside in the nuclear reactor. The temperature and stress distributions are analyzed and compared with the tests; the effects of the insulation layer thickness and support interval are investigated. The maximum stress occurs at the support points. The maximum stress increases approximately linearly with the increase of the support interval. The maximum deflection occurs at the middle of the two supports. The maximum deflection increases rapidly with the increase of the support interval, which is approximately in a parabolic relationship. The axial elongation ratio increases with the insulation layer thickness. The simulation results agree with the test results very well with regard of both stress and temperature distributions. The simulation method can also be used for the stress and temperature analysis in various cases, such as chemical-vessel and gas-oil pipeline with various thermal fluids inside. [ABSTRACT FROM AUTHOR]

As an important hub for crossing river cliffs in road transportation, the protective effect of bridges has always been the focus of research. In this paper, LS-DYNA software is used to simulate the process of explosion shock wave damage to large single-span T-beam bridge, and the influence of explosive type, detonation position and bridge reinforcement on the damage degree of bridge deck is studied. The results indicate that WY-1 explosive has the most severe impact on bridge damage among GOL-2 and WY-1 explosives. When only reinforcing steel is laid on the flange of the T-beam, the blast resistance performance of the bridge is significantly improved compared to without reinforcing steel. When explosives detonate at different positions on the bridge deck, there is no substantial damage to the entire bridge. But when the equivalent explosive is placed on the ground near the bridge pier, the pier completely fractures, the bridge collapses, and loses its load-bearing function. The research results provide a reference for the protection of bridges under explosive loads. [ABSTRACT FROM AUTHOR]

The Armed Forces of Ukraine pay great attention to the development of personnel protection armor. However, despite the availability of protective equipment, the practice of warfare shows that the tasks of protecting military personnel are not fully resolved. The task of developing protective structures against bullets and shrapnel remains urgent. The analysis of scientific and technical information showed that the processes that occur during the impact interaction of elements of mechanical systems have not been fully studied, and the development of means to protect against kinetic damage has not been fully covered in scientific papers. The process of interaction between the impactor and the protective barrier may change if nested structures are used as a protective barrier. The possibility of developing a new method for increasing the strength of armor protection by using nested structures (bullet–cylinder) is investigated. A new analytical dependence for determining the depth of penetration of a bullet into a cylinder is obtained. The novelty of the analytical dependence lies in the absence in the scientific literature of a mathematical model of bullet penetration into a cylinder whose inner diameter is smaller than the outer diameter of the bullet, taking into account the effective friction coefficient between the bullet and the inner surface of the cylinder, and the fact that the depth of penetration of a bullet into a cylinder can be equal to the length of the bullet, or be greater or less than it. On the basis of the proposed analytical dependence for determining the depth of penetration of a bullet into a cylinder, the dependences of the depth of penetration of a bullet into a cylinder on the value of tension (between the bullet and the cylinder) and the thickness of the cylinder are constructed. The research results indicate the fundamental possibility of reducing the depth of penetration of a bullet by using nested structures. [ABSTRACT FROM AUTHOR]

In nuclear reactors, turbulent excitation is an essential mechanism of flow-induced vibration. Turbulence exists everywhere in the heat transfer tubes, fuel rods and valves. Among three main research methods for turbulence excitation, the first is the fluid-structure coupling method, which can fully consider the fluid structure coupling effect but has not yet obtained a strict mathematical solution. The second is to make reasonable assumptions and use the classical random vibration theory to calculate the vibration response of the structure. This method is simple and efficient, but it cannot consider the nonlinear factors such as clearance, collision and friction. Thirdly, the transient analysis method is used to calculate the vibration response of the structure. This method can consider nonlinear factors, and the difficulty is to obtain the time history of turbulent excitation force acting on the structure. This paper presents a calculation method of the correlation length of the power spectral density function of two-phase flow in the heat transfer tube of steam generator based on global optimization fitting, which can determine the correlation length of the power spectral density function of two-phase flow in the heat transfer tube of steam generator efficiently and conveniently. It provides necessary input for the time history of power spectral density to turbulent excitation forc, and lays a foundation for more accurate transient analysis method for random turbulent excitation vibration analysis, design improvement, and safety evaluation of tube bundle equipment. [ABSTRACT FROM AUTHOR]

In this paper, the composite patch was prepared by wet spreading method, with which the damaged aluminum alloy specimen was repaired by bonding. The effects of different surface processing and curing modes on the fatigue properties of the specimens were studied. The results show that the surface coating coupling agent can significantly improve the fatigue properties of the repaired specimens; compared with unrepaired specimens, the fatigue life was increased by about 6.26 times and compared with uncoated specimens, the fatigue life was increased by 13.2–32.4%. Compared with unrepaired specimens, the fatigue life of repaired specimens can be increased by 6.20 times by heating and pressure curing. The fatigue life can be increased by 7.8–18.5% compared with normal temperature curing and repairing. Finally, the fatigue fracture of the specimen was observed and analyzed by SEM. [ABSTRACT FROM AUTHOR]

The paper presents and analyzes the results of experimental studies to determine the dissipative properties of a multilayer polymeric composite material reinforced with T300 twill weave carbon fabric in the temperature range from –140 to 230°C. The study was carried out by the method of free damped vibrations of prismatic specimens of the above material under pure bending conditions, which makes it possible to achieve uniformity of deformation along their length. The research method is described, and a block diagram of an experimental setup for the automated determination of the dissipative properties of composite materials is presented. The dependence of the logarithmic decrement of vibrations on the amplitude of cyclic strain in the range (1–10)×10–4 is taken as this characteristic. The experimental data were obtained for a braided composite along the weft, the warp, and at an angle of 45° to it. It is shown that at low temperatures (–60°C) and glass transition temperatures (130°C), the carbon fiber plastic exhibits a peak in dissipative capacity due to phase transitions in its polymer matrix. At elevated temperatures, the increase in the logarithmic decrement of carbon fiber plastic vibration is an order of magnitude greater than at low temperatures and is accompanied by a significant drop in the elastic modulus. It has been established that with an increase in the thickness of the test specimens, which is determined by the number of layers, the effect of phase transitions in the matrix on the level of energy dissipation in carbon fiber plastic is less pronounced. The obtained experimental data indicate a significant anisotropy of the characteristics of vibration energy dissipation and their dependence on the amplitude of cyclic strain. [ABSTRACT FROM AUTHOR]

Recently, much attention has been paid to the study of the deformation and failure features of high-strength steels under extreme loads, under which they are mainly operated. One of the topical issues is the correct determination of the parameters of deformation models of materials. The use of tests for barrier penetration at high speeds of 100–1000 m/s is quite complicated and expensive, and also does not allow to obtain enough information. Therefore, alternative experimental methods have been developed recently, which include static and dynamic punching tests of thin sheet specimens at speeds of up to 10 m/s. Such tests are simpler and allow to obtain more information about the behavior of high-strength materials in conditions that simulate operational ones. This paper presents the results of static and dynamic punching tests on thin sheet specimens of 50×50 mm size and 1 mm thickness made of Armox 500T armor steel. The static punching tests were carried out on an Instron 8802 servohydraulic machine, for which special equipment was manufactured. The dynamic punching of thin-sheet specimens was carried out on an instrumented vertical impact tester equipped with a high-speed strain and force recording system. To conduct such tests, the experimental equipment was updated, and a design of special supports for the rigid fixing of thin-sheet specimens was developed. The loading speed was varied from 0.5 to 10 mm/min for static punching and from 3 to 5 m/s for dynamic punching. The tests were conducted using three types of punches: conical, flat and hemispherical. According to the test results, new data on the influence of strain rate on the features of deformation and failure of Armox 500T armor steel were obtained. The influence of the type of punches on the nature and mechanisms of failure of thin-sheet specimens under static and dynamic punching was investigated. It was found that an increase in loading speed leads to an increase in specimen failure force. Thus, the resistance to deformation increases by approximately 20% with an increase in the loading speed from 0.5 mm/min to 5 m/s. [ABSTRACT FROM AUTHOR]