Lode-Nadai Coefficient Research Articles

Сейсмотектонические деформации и сброшенные напряжения землетрясений Центрального Тянь-Шаня

Based on the seismic moment tensor (SMT) data of 270 earthquakes in the Central Tien Shan, which occurred from 1978 to 2021 and include 63 events from the Global Centroid Moment Tensor catalog and 207 events from the works of Aleksander D. Kostyuk and Naylya A. Sycheva, the focal parameters (seismotectonic deformations (STD), kinematic and dynamic parameters, source radius, and stress drop) were calculated. The STD calculation was based on the approaches proposed in the studies of Yuriy V. Riznichenko and Sergei L. Yunga. The area under consideration is characterized by such deformation modes as thrust, transpression, underpression, and oblique. The distribution of the Lode–Nadai coefficient was calculated and plotted. A significant part of the study area is characterized by simple compression deformation, dominated by simple compression and simple shear. To calculate the stress drop , the values of the scalar seismic moment M0, which are determined in the SMT calculation, and the source radii r, which are calculated on the basis of theoretical and experimental models of the dependence of the source radius on the moment magnitude, were used. The radii r and stress drops  were calculated for two models of earthquake sources: the Brune model and the Madariaga–Kaneko–Shearer model. A catalog of dynamic parameters was compiled. The comparison of the kinematic and dynamic parameters of earthquakes was carried out, and the relationship of the dropped stresses with the type of movement in the source, as well as with the Lode–Nadai coefficient, was established. The results obtained in the study can be useful for specialists in other fields of knowledge – geodesy, geology, and geophysics.

ПОЛЯ НАПРУЖЕНЬ ТА ГЕОЛОГІЧНА СТРУКТУРА ЗАХІДНОГО ЗАМИКАННЯ ГОРЛІВСЬКОЇ АНТИКЛІНАЛІ ДОНБАСУ ЧАСТИНА 2. ПОЛЯ НАПРУЖЕНЬ І ДЕФОРМАЦІЙ

Background. In tectonophysical studies, particular importance is placed on the mechanism of formation of large complex deformation structural elements, and the Horlivka anticline of the Donets Basin serves as such an example. Its importance lies not only in its complex structural composition and development mechanism but also in its potential impact on safe and efficient coal mining. This study aims to analyse the geological structure, stress and strain fields of the western closure of the Horlivka anticline that could be useful in forecasting geological factors for coal mining operations. Methods. The paleostress analysis was performed on the collected fault orientation and kinematic data using Gushchenko's kinematic method based on the analysis of tectonic displacement vectors along slickensides. Mesoregional stress field characteristics were reconstructed by statistical processing of local stereographic solutions. The relative age chronology and staging of tectonic stresses were studied using the stress monitoring method. The characteristics of the principal axes of the total strain field were processed using the GEOS software. Results. Mesoregional stress field is characterised by a subhorizontal NW–SE-oriented maximum principal stress axis and a subhorizontal NE–SW-oriented minimum principal stress axis. This stress regime is classified as a strike-slip regime and is the youngest one (Alpine orogeny) for the Donets Basin. The evolution of tectonic loading conditions of the studied structure is characterised by a deformation series of six stress regimes from the oldest (normal) to the youngest (strike-slip). Stretching axis of the strain ellipsoid is oriented NW and N–S, and shortening axis is oriented NE, nearly orthogonal to the anticline axis. Strike- and oblique-slip faulting regimes of the total strain field were determined for most of the study area, and the deformation has occurred under shear conditions, as indicated by the Lode–Nadai coefficient. Conclusions. A structural pattern of deformation elements, including a conjugate strike-slip fault system of the shear zone, a dome-shaped fold, and longitudinal thrusts in its limbs, may be interpreted as a single pattern of structural paragenesis developed by right-lateral displacements along the longitudinal strike-slip fault system within the Horlivka anticline paraxial part. Fragments of mutual symmetry between the stress and strain fields can be taken as evidence of their genetic relationship.

DAMAGE ACCUMULATION IN THE V95\3% TIC METALMATRIX COMPOSITE DURING DEFORMATION AT HIGH TEMPERATURES

Damage accumulation in a dispersion-strengthened metal matrix composite was studied at deformation temperatures ranging between 300 and 500°C. The composite has the V95 alloy matrix (the Russian analogue of the 7075 alloy) reinforced by titanium carbide (TiC) particles in a volume content of 3%. The composite was made by ex-situ liquid-phase technology. Damage calculation is based on the data of the evolution of the elastic modulus value obtained by the instrumented microindentation technique. It has been experimentally found that, under compression at the macroscale, the composite has the best plasticity at a temperature of 400°C. The plasticproperties at a deformation temperature of 500°C are significantly lower than at 300 and 400°C. ranging from 300 to 500°C and strain rates ranging between 0.1 and 10 s-1. The paper presents experimental dependences between flow stress and strain for temperatures ranging from 300 to 500°C and strain rates ranging between 0.1 and 10 s-1. Based on these data, finite element simulation of specimen compression was carried out, which makes it possible to describe the influence of loading conditions on the evolution of the stress state characterized by the Lode-Nadai coefficient mσ and the σ/T ratio, where σ is mean normal stress and T is tangential stress intensity.

Development and Computer Simulation of the New Combined Process for Producing a Rebar Profile

The study presents results of computer simulation by finite elements method of a new metal forming process combining the deformation of a billet with round cross-section on a radial-shear rolling mill and subsequent billet twisting in a forming die with a specific design. To analyze the efficiency of metal processing, the main parameters of the stress–strain state are considered: effective strain, effective stress, average hydrostatic pressure, and Lode–Nadai coefficient. The maximum value of effective strain up to 13.5 is achieved when a screw profile on the billet in the die is forming, which indicates an intensive refinement of the initial structure of the billet. During combined process, the nature of the deformation changes in the transverse direction from the axis of rotation to the surface. The central area of the billet is under the action of tensile stresses. In the peripheral part, compressive stresses grow. In the surface area, Lode–Nadai coefficient is 0.1 approximately, which indicates the high level of shear strain.

Сейсмотектонические деформации Алтае-Саянской горной области. Часть 1

Seismotectonic deformations (STD) of the Earth’s crust in the Altai-Sayan mountain region were studied. The STD calculation was performed on the basis of the approaches proposed in the works of Yu.V. Riznichenko and S.L. Yunga. Estimation of seismicity distribution and calculation of the average annual STD velocity (STD intensity) IƩ were made on the basis of the catalog of earthquakes that occurred in 1997–2020 (15 669 seismic events). Areas of manifestation of intense seismotectonic deformations and seismic activity are identified. A high level of seismicity and the average annual STD velocity (10–7 year–1) is noted in the areas where strong seismic events occurred (Chuya earthquake on September 27, 2003, Tuva earthquakes on December 27, 2011 and February 26, 2012). The study of STD directionality is based on data on the focal mechanisms of earthquake sources (591 events) that occurred from 1963 to 2021. The classification of STD modes was used to construct the STD map. According to the STD maps, the direction of the shortening axes was determined, which changes from west to east from northwest to northeast. The study area is characterized by a variety of deformation conditions: compression, transpression, strike-slip, transtension, tension, etc. Based on the averaged strain tensors, the distributions of the Lode–Nadai coefficient, angle of generalized plane strain, and vertical component are calculated and plotted. The zones where various modes of deformation, such as simple compression, the predominance of simple compression, shear, the predominance of simple tension and simple tension are manifested, are distinguished in the study area. Both uplift and subsidence of the Earth’s crust are noted in the study area depending on the deformation mode.

Tectonic Earthquake Source Mechanism Model Based on Moment Theory

During the construction of strategic facilities, micro zoning is required to determine the peak values of terrain acceleration due to possible earthquakes. The acceleration of the soil in this case strongly depends not only on the power of the earthquake, but also on the earthquake source mechanism and the geodynamic state of the terrain. The known dislocation models of a single dipole with a moment and a pair of dipoles without a moment of the earthquake source mechanism satisfactorily describe the observed effects of the quadrant stress distribution on the Earth’s surface during earthquakes. When carrying out calculations within the framework of the theory of elasticity, the actions of the dipoles are expressed through volumetric forces. There are two known models of replacing the moments with equivalent forces: one of them is based on the equilibrium equations for an infinitely elastic space (Landau and Lifshitz,1965; Maruyama,1963), and the other is based on the representation theorem for elastic bodies, by introducing a singular internal volume, at the boundary of which there are dislocations (Vvedenskaya, 1969; Aki and Richards, 1983). Although these models involve moment effects, they themselves are derived from the momentless theory of elasticity. In our work, we propose a double dipole effect without a moment based on the moment theory of elasticity. The proposed model of the earthquake source mechanism is applied to solve the problem of stress variations in the Earth’s crust in Central Asia using the example of a particular earthquake with a simplified orientation of the rupture plane. Stress variation is understood as the difference in stresses in problems with and without an earthquake mechanism. Static stresses are obtained by solving the inverse elasticity problem with partially unknown boundary conditions. The lithosphere is a prismatic body consisting of several homogeneous blocks, the upper surfaces of which correspond to the relief of Central Asia. Verification of the results of the numerical solution is carried out by comparing the obtained stresses with previously established empirical values. As a priori stresses for solving the inverse problem, we used the solution of the elastic plane problem, the boundary conditions in which correspond to the lateral compression of the lithosphere of the region of the Indian and Arabian plates on the one hand, and the Eurasian plate on the other hand. The obtained solutions of the problem were used to analyze the geodynamic state of Central Asia. Based on the results of laboratory experiments, the unambiguity of the conclusions about the geodynamic state of the Earth’s crust (compression, extension) according to the Lode-Nadai coefficient, which are currently used by many researchers, is questioned. It is shown, contrary to earlier statements, that the values μσ = +1 and μσ = –1 can correspond simultaneously to both tension and compression cases, depending on the spatial form (ellipsoid) of the stress state. Geodynamic analysis of the Earth’s crust is carried out according to the Anderson method.

Stress State of the Earth’s Crust, Seismicity, and Prospects for Long-Term Forecast of Strong Earthquakes in Uzbekistan

Abstract —The current stress state of the Earth’s crust on the territory of Uzbekistan is studied using algorithms from the cataclastic analysis of displacements (CAD) with the application of a combined catalog of earthquake source mechanisms. The axis of maximum compression is nearly horizontal and orthogonal to the strike of tectonic structures for the larger part of the area under study, and the angle of penetration of the axis of minimum compression varies greatly for different parts of the territory. The areal distribution of the Lode–Nadai coefficient indicates the predominance of a stress state close to pure shift for the area under study. Without differentiation of the seismically active bed by depth, almost the entire territory of Uzbekistan is characterized by a geodynamic stress state corresponding to horizontal compression. There are significant differences in the stress state parameters for different deep beds of the Earth’s crust. With account for the representative recording periods of seismic events of different energy levels, the earthquake recurrence parameters for the entire territory as a whole and large seismically active zones are determined. It has been established that the epicenters of strong earthquakes recorded since the historical time are grouped in compact areas with linear dimensions of 50–80 km. The tectonophysical interpretation of the selected areas is given within the framework of the CAD, in which it is noted that strong earthquakes occur mainly in areas of lower effective confining pressure and maximum tangent stresses. This is due to the fact that the values of friction forces at faults in such areas are low, which creates the most favorable conditions for large-scale destruction. According to the results of the reconstruction of the natural stresses of the CAD, such areas on the territory of Uzbekistan are identified within faults and flexural-fault zones in South Fergana and North Fergana, as well as in the Gazli region. The current seismological situation in the selected areas of long-term forecast is estimated using a set of prognostic parameters of the seismic regime, and a map of the areas of expected seismic activity is compiled. The analysis of previous forecast maps developed within the framework of the presented approach shows high value in their information.

Rock burst forecasting technique and selecting a safe coal face advance direction

Mine planning involves selecting an optimal mine layout. At the same time key factors, including those influencing mining safety, should be comprehensively taken into account. A developed rock burst forecasting technique taking into account mine workings of an extraction area and a mine goaf enables determining the safe direction of a coal face. The proposed technique also takes into account all faulting/joint systems, occurring beyond a mine field. The distribution of specific potential energy in an intact rock mass is proposed to be used as the basis of the input data required for rock burst forecasting. The forecast is carried out via estimating the Lode-Nadai coefficient at different directions of coal face advancing. The stress (intensity) coefficient is proposed to be used as a criterion in order to determine a safe direction. We determined the safety criterion is equal to 10 in the Komsomolskaya Mine conditions. Besides, the safest direction of a coal face advance to mitigate the risks of rock burst was determined for this mine. The direction between 138° and 128° counter-clockwise from the north direction was identified to be the safest for the Komsomolskaya Mine conditions for any values of deformation modulus and Poisson’s ratio.

Mathematical modeling of the stress state in the coating during the electromechanical treatment

The principal aim of this study is to determine the stress state in the thermal sprayed coating during the electromechanical treatment. The solution is performed using the finite difference method. Lode-Nadai coefficient and Bagmutov parameter are used to describe the stress state in the cross-section of the half-space with coating.

Improvement of the deformation technology in relief rolls by asymmetric rolling realization

Among many methods of improving metal products quality, metal forming methods, applying intensive plastic deformation, take a special place. Results of a study on perfection technology of plate workpieces deforming in relief rolls presented. Application of the technology ensures receiving by a workpiece additional level of shear deformation in transverse direction due to special design features of roll profile. Besides due to various rolls rotation speeds, state of kinematic asymmetry arises, which results in additional level of shear deformation in longitudinal direction. It was revealed by Deform program simulation of metal deformed state that the workpiece is not bent practically after getting out of the relief rolls, keeping its horizontal path of motion. It was shown that the effect is reached due to relief section of the workpiece, where micro-ridges and micro-cavities are formed acting as reinforcing ribs. At that the level of deformation increases by nearly 20% comparing with symmetric rolling in relief rolls. Analysis of state of stress by calculation of Lode‒Nadai coefficient showed that in the central zone of the workpiece mainly compressing stresses are formed, reaching maximum values in the area of comb; at the inclined sections due to action of shear deformations the level of compression is decreased. The surface zones have similar stress distribution comparing with the central one ‒ in the areas of combs compressive stresses are formed, which are considerably lower comparing with those of central zone. On the inclined sections the value of Lode‒Nadai coefficient tends to zero, which gives evidence of intensification of shear deformation in these areas. Analysis of workpiece deformation after rolling in the relief rolls and having next two passes in smooth rolls showed that the proposed variant of rolling technology enables to obtain at the exit a smooth workpiece with insignificant wedging out. Since initially the technology was elaborated for multi-stand mills, these wedging outs will be completely deleted during further passes where the workpiece will have definite reduction by thickness.

RECONSTRUCTION OF THE TECTONIC STRESS FIELD IN THE DEEP PARTS OF THE SOUTHERN KURIL-KAMCHATKA AND NORTHERN JAPAN SUBDUCTION ZONES

Earthquake focal mechanisms in the Southern Kuril-Kamchatka and Northern Japan subduction zones were analysed to investigate the features of the tectonic stress field inside the Pacific lithospheric plate subducting into the upper mantle. Earthquake focal mechanism (hypocenter depths of more than 200 km) were taken from the 1966– 2018 NIED, IMGiG FEB RAS and GlobalCMT catalogues. The tectonic stress field was reconstructed by the cataclastic analysis method, using a coordinate system related to the subducting plate. In most parts of the studied seismic focal zone, the axis of the principal compression stress approximately coincides with the direction of the Pacific lithospheric plate subduction beneath the Sea of Okhotsk. It slightly deviates towards the hinge zone separating the studied regions. The principal tension stress axis is most often perpendicular to the plate movement, but less stable in direction. This leads to compression relative to the slab in some parts of the studied regions, and causes shearing in others. The hinge zone is marked by the unstable position of the tension axis and high values of the Lode–Nadai coefficient, corresponding to the conditions of uniaxial compression, while the compression direction remains the same, towards the slab movement. Two more areas of uniaxial compression are located below the Sea of Japan at depths of 400–500 km.

Stress State of Uzbekistan’s Seismically Active Areas

The current stress state of the Earth’s crust in the territory of Uzbekistan was studied by cataclastic analysis of displacements along fault sets for the collected catalog of earthquake focal mechanisms (EFM), compiled from the data of different authors. Two stages of stress field reconstruction are implemented at different levels of area detail of averaging parameters and for different magnitude hierarchies of the analyzed earthquakes. Azimuths and dip angles of principal stresses axes, Lode–Nadai coefficient values, geodynamic type of stress state, relative (normalized to the cohesion strength of the rock massif) normalized values of the maximum shear stress and effective pressure are determined for different areas of the studied territory. As a result of natural stress reconstructions based on the focal mechanisms of earthquakes with magnitudes M ≤ 4.5 and M ≥ 5, differences in the parameters of the stressed state were revealed. It has been suggested that the hierarchy of magnitude levels of the considered earthquakes reflects the stressed state of various deep layers of the crust. It is shown that strong earthquakes gravitate to zones of reduced effective pressure. On this basis, segments of active faults have been identified in the territory of eastern Uzbekistan, which are considered zones of potentially increased seismic hazard.

Tectonophysical criteria for forecasting the locations of quartz crystal deposits (case of Subpolar Ural)

Spatial reconstruction of tectonic stresses within the Subpolar Ural quartz crystal-containing province was conducted by the kinematic method [Gushchenko, 1973, 1979] based on the main indicators of tectonic stresses on slickensides. Local stress states (LSS) and general stress fields for large blocks were reconstructed by the method described in [Sim, Marinin, 2015]. In the blocks with numerous occurrences of quartz crystal (Pelingichey and Omega-Shor blocks), the general stress fields is characterized by a stress state close to uniaxial tension, i.e. the Lode-Nadai coefficient µ=–1. In these blocks, thick quartz veins are perpendicular to the tension axis of the general stress field. In the block without quartz crystal (West Saled), the general stress field is characterized by a triaxial stress state or pure shear state (–1˂µσ˂+1). The LSS of the quartz crystal deposits show the following: the stress state of µ=–1 is typical of quartz veins without quartz crystal nests, and a special kind of stress state is reconstructed near the nests with piezoelectric material. It is named a variation of the type of stress state (VTSS), which means that within one tectonic stage, the type of stress state changes approximately as follows: µσ=+1 (40 %), µσ=–1 (40 %), and –1˂µσ˂+1. It means that in the piezoelectric mineral deposits, pulsating tectonic stresses provided for a fluid flow of hydrothermal solutions at the intersection of ore-bearing and ore-controling faults when tension (µ=–1) was replaced with compression (µ=+1), while the orientations of compression and tension axes remained unchanged. Apparently, such a regime was caused by alternating activation of the above-mentioned faults. The tectonic stress reconstructions were performed for 33 mineral deposits and occur­rences of quartz crystal. VTSS was determined in 32 deposits; one mineral occurrence is characterized by uniaxial tension. Therefore, we propose using VTSS (variation of the type of stress state) as a criterion for predicting the locations of quartz crystal deposits.

The stress state of the Sakhalin Island and adjacent territories

The present study presents the results of the stress tensor inversion in the Sakhalin-Island and adjacent territories. The method of cataclastic analysis of discontinuous displacements has been used to perform the stress reconstruction. The stress inversion has been performed on the basis of local focal mechanism solution catalog of earthquakes, NEID and Global CMT Project data. The calculations are carried out at three depths levels (0–6 km, 6–12 km and 12–18 km) for magnitude range (Mw) 3.0–7.0. The results of the stress reconstruction allowed us to obtain the new specific features of the tectonic stress field: orientation of the principal stress axes, stress ratio or Lode-Nadai coefficient and the types of stress (the geodynamic regimes). The tectonic stress field is less stable at depth between 6 and 12 km.

Analysis of the Stress-Strained State of Billets Processed by Rotary Forging with Special Shape of the Tool

In this paper, we investigated the process of rotary forging of commercially pure copper grade M2 ​​using standard and special-shaped anvils and presented the results of studies obtained by the method of numerical and physical modeling. It is established that the use of anvils with special geometric shapes provides a higher level of accumulated strain and the formation of more dispersed structural states with the same elongation ratio under conditions of multi-cycle processing [1]. The formation of a finer structure in its turn increases the hardness and strength of the material. In addition, the special shape of the anvils provides a positive field of values ​​of the Lode-Nadai coefficient in the cross section of the samples, predominantly in a range of 0.3-0.7 and, correspondingly, a more "comfortable" stress state close to non-uniform all-round compression, which contributes to increasing technological plasticity.

A Numerical Study of Plastic Strain Localization and Fracture in Al/SiC Metal Matrix Composite

Plastic deformation and fracture of Al/SiC metal matrix composite have been numerically simulated in three mechanical tests (tension, compression, shear) with account for the microstructure and rheology of the composite components. A description is given of the formation mechanisms of stress concentration zones and local plastic deformation zones which make the stress-strain state inhomogeneous on the microscale. Distribution fields are obtained for the stress stiffness coefficient and the Lode-Nadai coefficient depending on the strain. Damage accumulation is simulated and damage distribution fields in the composite matrix are constructed with regard to the revealed stress-strain evolution laws. The strain dependences of the fraction of finite element nodes for which the fracture condition is fulfilled are determined. The dependences are used to estimate the damage accumulation rate in the composite matrix for each type of loading.

ДИАГРАММА ПРЕДЕЛЬНОЙ ПЛАСТИЧНОСТИ АЛЮМИНИЙ-ГРАФЕНОВОГО МЕТАЛЛОМАТРИЧНОГО КОМПОЗИТА С СОДЕРЖАНИЕМ ГРАФЕНА 2 МАС. % ПРИ ТЕМПЕРАТУРЕ 300 °С

Deformation behavior of a 2 wt% aluminum-graphene metal matrix composite (MMC) at 300 °C is studied. The MMC under study is synthesized at the Institute of High-Temperature Electrochemistry, Ural Branch of RAS. Data on ultimate ductility of the MMC is obtained. The value of shear strain to fracture is used as the characteristic of ultimate ductility. The shear strain to fracture is the function of the stress triaxiality coefficient and the Lode-Nadai coefficient. Tensile tests of smooth cylindrical specimens, notched cylindrical specimens, tensile and compressive tests of bell-shaped specimens, and tests of thick-walled cups with thinned bottoms are used to study ultimate ductility. The fracture locus of the composite at 300 °C is identified by the results of the study. It has been determined that graphene increases the ductility of aluminum, even under conditions of prevailing tensile stresses. However, the influence of graphene is significantly dependent on the form of the stress state of the metal under deformation. The composite under conditions of tension of smooth cylindrical specimens manifests practically unlimited ductility. The specimens underwent plastic deformation till the moment of the physical separation of specimen parts in the fracture region, while the cross section of the specimen in the neck tended to zero. However, when thick-walled cups with thinned bottoms are tested, the influence of graphene on ductile properties of the MMC can be neglected. Under conditions of prevailing compressive stresses, the ductility of the MMC significantly increases for all the test types. The obtained fracture locus is compared with the fracture loci of commercially pure aluminum and the 1 wt% aluminum-graphene MMC. It has been determined that the ductility of the material increases with graphene content.

Alternating Sign Rolling Technology in Grooved Rolls for Nonferrous Metal Plate Billets

Results are given for a study of rolling plate metal by technology including rolling in grooved rolls and levelling on a smooth barrel. Results of computer modeling and analysis of the Lode–Nadai coefficient show that during rolling in grooved rolls two types of deformation-compression arise in a billet cross section, i.e., compression in inclined areas and shear in ridged zones. This picture of stress distribution is most favorable since compressive strain leads to “healing” of possible metal discontinuities, but shear deformation leads to intense working of the original metal structure. During rolling in the first pair of smooth rolls deformation compressive in nature predominates, and in the second pair of rolls it is deformation alternating in nature. In any billet vertical section, metal contact with rolls occurs on both surfaces, i.e., upper and lower, which leads to compression in ridge zones, but to tension in inclined sections. Analysis of the results of metallographic studies points to the benefits for rolling in grooved rolls in the plan of preparing a metal fine-grained isotropic structure. The use of grooved rolls leads to significant strengthening of L63 brass compared with using smooth rolls with an identical overall degree of deformation.

Stress state reconstruction and tectonic evolution of the northern slope of the Baikit anteclise, Siberian Craton, based on 3D seismic data

In this work, we consider application of an original method for determining the indicators of the tectonic stress fields in the northern Baikit anteclise based on 3D seismic data for further reconstruction of the stress state parameters when analyzing structural maps of seismic horizons and corresponded faults. The stress state parameters are determined by the orientations of the main stress axes and shape of the stress ellipsoid. To calculate the stress state parameters from data on the spatial orientations of faults and slip vectors, we used the algorithms from quasiprimary stress computation methods and cataclastic analysis, implemented in the software products FaultKinWin and StressGeol, respectively. The results of this work show that kinematic characteristics of faults regularly change toward the top of succession and that the stress state parameters are characterized by different values of the Lode–Nadai coefficient. Faults are presented as strike-slip faults with normal or reverse component of displacement. Three stages of formation of the faults are revealed: (1) partial inversion of ancient normal faults, (2) the most intense stage with the predominance of thrust and strike-slip faults at north-northeast orientation of an axis of the main compression, and (3) strike-slip faults at the west-northwest orientation of an axis of the main compression. The second and third stages are pre-Vendian in age and correlate to tectonic events that took place during the evolution of the active southwestern margin of the Siberian Craton.

Evaluation of the effectiveness of the use of horizontal and vertical rolls in the “Rolling-pressing” process on the basis of the stress-strain state studying

In this work was performed a comparative analysis of the efficiency of horizontal and vertical rolls in the “rolling-pressing” process. The comparison was performed based on the study of stress-strain state of both variants with the aid of computer simulation in the program DEFORM-3D based on the finite element method. For analysis of the stress state was used the Lode-Nadai coefficient, allowing you to determine which type of deformation is realized at a specific point – tension, compression or shear. For analysis of the strain state was used equivalent strain, which allows to estimate the common level of accumulated strain. In the comparative analysis of parameters of SSS was revealed that the use of vertical rolls at the exit from the matrix during “rolling-pressing” process, allows you to achieve a more favorable distribution of deformation along the entire length of the deformable workpiece.