PNRPU Mechanics Bulletin最新文献

{"title":"Elastic-plastic invariant of autowave plasticity","authors":"","doi":"10.15593/perm.mech/2021.4.14","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.4.14","url":null,"abstract":"It is shown in the work that plastic flow in solids develops always in localized manner. A macroscopic scale ~ 10-2 m characterizes the localization. The localized flow zones form the pattern of localized strain, which is the projection of the autowave processes of plastic flow, developing in the volume, on the observed surface of the tested specimen. One can observe the pattern with the help of speckle-photography method. The investigations of various materials allowed to establish that the pattern of localized deformation is the information source for a kinetics of deformation processes. A general characteristic of localized plastic flow in solids is the elastic-plastic invariant of deformation which couples the typical characteristics of localized plastic flow autowaves with the same for the elastic waves in crystal lattice. The quantity of the invariant ratio is defined for nearly forty various materials (BCC, FCC, HCP metals and alloys, alkali-halide crystals, ceramics, rocks) studied in the conditions of active elongation and compression at the temperature range 143-420 K. The physical considerations are presented to explain the invariant origination and its relation to other physical characteristics of crystal lattice, in particular, the Debye temperature. In the light of these considerations, it is possible to explain the meaning and the origin of the invariant, and to derive numerous consequences from them. In fact, the set of these consequences comprehend all the regularities of developed plastic flow processes and allows to consider the elastic-plastic invariant of deformation as the master equation for developing this day autowave approach to physical theory of plastic deformation.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42337194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Applied mechanical and mathematical model of grinding of a solid particle by static crushing","authors":"G. A. Guryanov, B. M. Abdeev, S. R. Baigereyev, V. A. Kim, A. Suleimenov","doi":"10.15593/perm.mech/2021.3.06","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.06","url":null,"abstract":"Now crushers are one of the most common types of crushing equipment using the principle of a mechanical method of material destruction (for example, rollers, jaws, cone crushers, etc.). To provide effective parameters of the crusher, it is necessary to take into account the correlation between the physical and mechanical characteristics of the material (sizes, shapes, strengths, fragility, uniformity, etc.) and the energy parameters of the crusher (operation and power) at the design stage. The existing theories describing the mentioned dependence and relying on different classical hypotheses allow obtaining a very approximate (inaccurate) result. Consequently, it is necessary to develop a detailed theory of crushing capable of an accurate description of the mechanical process of material destructions by working members of the crushers. Thus, the authors have developed the crushing theory as an original solution of a complex constructively nonlinear engineering and technical problem on the static contact of a spherical model of a comminuted brittle substance with absolutely rigid convex-concave surfaces of cylindrical rolls designed for coarse and medium grinding. The theory is based on the classical assumptions of the mechanics of an elastically deformable continuous medium, the fundamental analytical dependences of Hertz-Shtaerman and the Kirpichev-Kick volumetric energy hypothesis. During the quantitative assessment of the bearing capacity of the ball, we used the well-known physical and mathematical problem of Weber on the stress state of a sphere loaded by two equal forces applied at the poles, and the Kulon-Mor’s strength criterion, which describes the process of destruction of a wide class of brittle homogeneous materials. The developed theory of fragmentation has been brought to the design formulas and illustrated with a typical numerical example.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47058819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of the hot isostatic pressing process","authors":"A. A. Khlybov, E. S. Belyaev, A. D. Ryabtsev, D. Ryabov, S. Belyaeva, Yu. A. Getmanovsky, P. M. Yavtushenko","doi":"10.15593/perm.mech/2021.3.18","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.18","url":null,"abstract":"This work, models the compaction of a dispersed body under the conditions of a hot isostatic pressing (HIP) cycle using the example of the manufacture of compacts from VZh159ID powder and Inconel alloy 718. For the research, VZh159ID powder of fraction -70 + 25 μm, bulk density of 3.77 g/cm3 (4.83 g/cm3 after tapping), fluidity of 2.3 g/s, specific surface area of 446 cm2/g, and average particle size was used according to Fisher 16 microns, as well as Inconel alloy 718 powder of fraction -315 + 25 microns, bulk density 3.84 ... 4.58 g/cm3 (4.52 ... 5.24 gcm3 after tapping), fluidity 1.58 ... 1.90 g/s, specific surface 330 ... 376 cm2/g and average particle size according to Fischer 19.0 ... 19.5 microns. Before the HIP cycle, the powder backfills underwent thermal degassing in vacuum, since powders with such a high specific surface are subject to rapid gas sorption. Gases on the surface of the powder body as a result of the HIP cycle can form non-metallic inclusions that reduce the properties of the compact. In the microstructure of compacts after HIP, there is no network of residual boundaries from granules (PPBs-Prior Particle Boundaries), which indicates an effective technology of vacuum degassing of the powder. Simulation of the compaction process was carried out according to the modernized equation of E. Ryshkevich, constants b were selected for the materials considered. The results of the experiments of interrupting the HIP cycle and data on the strength of the samples at high temperatures obtained by selective laser sintering were used as the initial data for modeling. The proposed modeling method is quite simple (does not require experiments on an interrupted HIP cycle) due to the shown possibility of experimentally determining the strength characteristics of alloys at elevated temperatures on samples obtained by selective laser sintering. The analysis of the obtained microstructures (estimation of porosity) of the samples after HIP, having different density values, shows a good agreement of the proposed model with the real process of compaction in the gasostatic extruder.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48355802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of thickness on residual flexural strength of composite with low-velocity impact damages: Experimental study","authors":"O. Kudryavtsev, A. Ignatova, N. Olivenko","doi":"10.15593/perm.mech/2021.3.01","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.01","url":null,"abstract":"","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45031079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of plastic compressibility on the strain rate intensity factor in compression of a material layer between parallel plates","authors":"","doi":"10.15593/perm.mech/2021.3.16","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.16","url":null,"abstract":"Solutions of boundary value problems for several rigid plastic models may be singular. In particular, some components of the strain rate tensor and the quadratic invariant of the strain rate tensor may approach infinity in the vicinity of certain surfaces. Some models for predicting the high gradient of material properties near frictional surfaces in metal forming processes are based on such behavior of the velocity field. The coefficient of the leading singular term in a series expansion of the quadratic invariant of the strain rate tensor in the vicinity of frictional interfaces is called the strain rate intensity factor. The magnitude of the second invariant of the strain rate tensor is controlled by this factor that depends on geometric parameters of the boundary value problem and parameters involved in the material model. The present paper deals with the effect of plastic compressibility of the material that obeys the double shearing model on the strain rate intensity factor in compression of a plastic layer between two parallel plates. The system of equations comprising the equilibrium equations and constitutive equations is hyperbolic. It is assumed that the surface of the contact between the plates and the deforming material is an envelope of characteristics. An analytic solution of the boundary value problem is found under plane strain deformation. End effects near the free surface of the layer and its center are ignored. The dependence of the strain rate intensity factor on parameters of the boundary value problem including the parameter that controls plastic compressibility is found. In case of the plastically incompressible material, the solution coincides with the available solution.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47382459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of gyroscopic forces in the oscillatory system of a Coriolis flowmeter","authors":"V. Romanov, V. P. Beskachko","doi":"10.15593/perm.mech/2021.3.12","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.12","url":null,"abstract":"The phase difference between the oscillations of the Coriolis flowmeter (CFM) arms is the main experimentally observed parameter during measurements of liquid flow rates in pipelines. Usually, steady-state oscillations and known dependences between the flow rate and the measured phase shift are assumed. However, these conditions are met with a sufficient accuracy only for homogeneous and single-phase flows. For inhomogeneous and multiphase flows, the correction of measurements is necessary. This correction in most cases is empirical. However, to improve the methodology of Coriolis flowmeter measurements, more detailed information about flow-tube interactions is needed. The experimental obtaining of such data is expensive and laborious. On the other hand, this data can be acquired during numerical experiments on the CFM virtual prototype. However, to effectively simulate liquid flows, it is necessary to separate the contribution of gyroscopic and dissipative forces to the experimentally observed signal (phase shift). This problem is complicated by the fact that gyroscopic forces are not uniformly distributed along the length of the tube, and the model for dissipative forces is not sufficiently developed yet. In this work, gyroscopic forces were separated by the 3D finite element modeling of steady-state oscillations of a tube with the ideal (inviscid) liquid. We discussed the usage of the simulation results in a simplified discrete model. It is shown that the magnitude of the phase shift recorded by the flowmeter depends both on the features of the distribution of gyroscopic forces and on the elastic coupling of the natural vibrations of the elastic tube caused by the fluid flow. The influence of the tube shape on the experimentally observed phase shift was investigated. For the tube shapes considered in the work, the difference in the phase shift for the displacements of the sections of the installation of the recording coils reaches nearly 5 times. The parameters of both gyroscopic and elastic coupling depend on the shape of the tube, and a change in the shape of the tube can increase the gyroscopic coupling and decrease the elastic one, and vice versa. The creation of a simplified discrete model of the flowmeter based on the results of the 3D finite element calculations is discussed. The quantitative estimates of the integral parameters of the oscillatory system of the CFM are carried out, allowing one to compare both the magnitude of the gyroscopic forces arising during the flow of the liquid and the degree of conformity of the tube shape to the special requirements for the oscillatory system of the CFM.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43492902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Importance of thermal conductivity and stress level during a phase (hydride) transformation in magnesium","authors":"","doi":"10.15593/perm.mech/2021.3.02","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.02","url":null,"abstract":"There are many different systems of an autonomous energy storage including accumulators and storage devices for renewable energy. Systems based on reversible metal hydrogenation have recently been introduced. The selection of metals is based on considerations of temperature and pressure conditions of the hydrogenation/dehydrogenation cycle, as well as the desired storage hydrogen capacity. Magnesium is one of the main challenging metals with respect to these main conditions since having a hydrogen capacity up to 7.6 w.%. For Mg forming MgH2, it was soon established that the size of particles plays a critical role since the kinetics (rate) of hydride formation accelerates when the size of the particles decreases. The present study shows that the overall diameter of the particles is the main characteristic controlling the kinetics of hydride formation because of distinct issues. A distribution of the size entails a strong dispersion transferring the heat of reaction, which characterizes Mg to MgH2 phase transition. Moreover, the formation of MgH2, is accompanied by a great increase of the unit-cell volume, developing noticeable internal stresses within the surface layers of the particles, thus turning to a systematic flaking and a systematic decrease of sizes of the powder particles. The results of the numerical modeling comply with the experimental data. This makes it possible to predict the best size of the initial Mg powder able to achieve fast kinetics during hydrogenation. Furthermore, the present analysis demonstrates the best hydrogenation kinetics, not only when using fine powders, but also when the deviation from the average particle size is minimized.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42927968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of rubber-cord layers under quasi-static loading","authors":"S. Sheshenin, Duan Yikun, P. Chistyakov, N. Artamonova","doi":"10.15593/perm.mech/2021.4.06","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.4.06","url":null,"abstract":"Modeling a pneumatic tire with a strong change in shape causes the problem of choosing an adequate model for rubber-cord plies. Generally, the classical method of asymptotic homogenization is not suitable due to physical and geometrical nonlinearity for the strain up to 15 %. The known models used for simulation the entire tire as well as rubber-cord plies are analyzed. A choice is made in favor of modeling the plies using the stress anisotropic potential, which is an anisotropic function of the strain tensor invariants. The relationship of such a constitutive law with a quasi-linear constitutive equation in terms of stress and strain differentials is indicated. A convenience of these two types of constitutive equations in terms of numerical implementation is also given. A modification of the effective properties definition for an inhomogeneous layer is explained. The difference from the standard effective moduli definition is clarified. The arrangement of the cords is supposed to be approximately periodic and all cords to be equivalent to the effective fiber. Two models of a rubber-cord plies are described under such assumption. These are a model of an orthotropic material and a model of a transversely isotropic material. Computational experiments, which make it possible to determine the material parameters of anisotropic potentials, are pointed out. Real tests with a sample of rubber ply under slow quasi-static loading were conducted. Significant hysteresis was detected. It is shown that an additive model combining a hyper elastic material with Maxwell viscoelastic model provides good accuracy in stress dependence on the strain rate. The numerical procedure developed to calculate solution to the quasi-static problem of tire deformation is described. It is implemented in home-made computer code. A numerical example on the tire simulation is given. That is so-called breaking test, in which strong deformation is achieved and the developed model is applied to.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46211341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of impact failure of tubular samples made of composite material, depending on the loading rate","authors":"A. Fedorenko, B. Fedulov, E. Lomakin","doi":"10.15593/perm.mech/2021.3.09","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.3.09","url":null,"abstract":"In this paper, a model that takes into account the dependence of strength properties on the damage rate is considered for modelling of the impact failure of composite materials. The constants of the material model are determined on the basis of experimental diagrams to compression and shear impact loading of unidirectional composite, which exhibit a nonlinear dependence on the strain rate. The proposed model is implemented to the Abaqus finite element modeling software for the case of a three-dimensional stress state. As an example of numerical modeling, we consider tubular composite specimens made of carbon fiber with an epoxy matrix and layers of different orientations, which are commonly used for determining of characteristics of impact energy absorption. Diagrams of impact loading of the considered tubular specimens are obtained. The influence of the chamfer (taper of the cross-section) on the edge of a tubular specimen on the impact loading diagram at the initial stage of the process, which serves as the initiator of crushing, is studied. The proposed approach allows us to estimate the magnitude of the peak of the amplitude associated with the crushing of the chamfer. In addition, at the initial stage of loading, maximum strain rates occur, which entails the hardening of the material, also expressed in the loading diagram as an increase in the amplitude. If the analysis neglects the effects associated with the strain hardening of the material and the geometry of the chamfer, the result may be expressed in an underestimation of the reaction, especially at the initial stage of the process. The absence of the described effects in the model of composite structures may lead to significantly incorrect results with complete failure with zero reaction. The developed approach is effective in the design and testing of damping elements made of composite material with properties that are sensitive to the loading rate.","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42379563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"© ПНИПУ Numerical and experimental research of the evaluation of the mechanical behavior of carbon fiber reinforced polymerspecimens with an embedded Smart-layer","authors":"M. Baranov, A. Nikiforov, A. Mikryukov, D. A. Ermakov","doi":"10.15593/perm.mech/2021.4.15","DOIUrl":"https://doi.org/10.15593/perm.mech/2021.4.15","url":null,"abstract":"Currently, scientists have paid special attention to the possibility of creating so-called Smart-structures that are capable of real-time self-diagnostics and/or functional changes. Within the framework of this work, the possibility of creating structures capable of diagnosing the deformation state in real-time is considered. When creating such Smart-structures, fiber-optic, piezo-, and strain-gauge sensors are usually used as control sensors. The use of such sensors is due to a number of their advantages, such as small size, the ability to integrate into a single measuring network, ease of use, a wide range of measured values, the ability to transmit data over long distances. However, when such sensors are embedded into the structure, several difficulties arise in installation/dismantling or implementation due to the fragility of the fiber, the difficulty of locating the sensitive element, ensuring the integrity of the fiber-optic sensors at the exit from the polymer structure. The team of the Scientific and Educational Center of Aviation Composite Technologies, PNRPU, has developed a prototype of a Smart-layer based on 3D-printing technology, capable of solving the problems described above. However, the influence of such an embedding on the structure of structures made of carbon fiber reinforced polymer (CFRP) remains open. Thus, this work aims to carry out computational and experimental studies to assess the mechanical behavior of CFRP samples with an embedded Smart-layer. Within the framework of this work, the technology and scheme for manufacturing a Smart-layer with embedded fiber-optic sensors, as well as a scheme for laying a Smart-layer into CFRP samples, are described. Since the properties of molded plastic specimens differ from those of printed specimens, mechanical tensile tests of printed specimens were carried out. The obtained values of the strength limit and the modulus of elasticity were used to identify the mathematical model. Within the framework of the experimental part, mechanical tests for tension, compression, and interlayer shear of CFRP samples with an embedded Smart-layer were carried out. When analyzing the obtained experimental results, it was found that the maximum percentage deviation of the physical and mechanical characteristics (PMC) is no more than 15 %, which lies within the spread of the PMC of carbon fiber in a prepreg roll. As a result, we can conclude that the embedded of such Smart-layers does not significantly affect the PMC of the final CFRP structure. According to the results of mathematical modeling of the tensile strength of a CFRP sample with an embedded Smart-layer, it was found that the maximum value of normal stresses in the sample reaches 540,28 MPa, which is 1,46 % higher than the maximum value for the statistical ultimate strength of the sample. The maximum values of the Mises stress for the Smart-layer do not exceed the ultimate strength, while for the epoxy binder there is a significant excess","PeriodicalId":38176,"journal":{"name":"PNRPU Mechanics Bulletin","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41787834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}