Dislocation Zone Research Articles

Stress-deformed state of the container with the presence of an displacement of the butt edges in the ring welded joint of the body

Capacitive equipment of oil refineries is widely used in the operation of technological units and plays one of the dominant roles, both in terms of metal consumption and the degree of use. Depending on the purpose, the required capacity of the stored product and constructive features, containers reach rather large overall dimensions, which creates certain difficulties in diagnosing the entire surface of the vessel. In the process of manufacturing and repairing the bodies of technological tanks, it is possible to form such a geometric defect as “displacement of the edges of the abutting elements” when welding cylindrical shells to each other by circular welded seams. In the presence of geometric defects of this type, additional stress concentrators are created in the areas of the presence of these defects, which may be a prerequisite for the transition of an object to the limiting state in a fairly short period of time from the action of increased pressures and temperatures. Also, the presence of displacement of the edges on the body of the capacitive apparatuses can have a negative effect on the stress-deformed state of the considered capacity as a whole and to the formation of dislocation zones of increased stresses. Therefore, the actual work is the study of the stress-deformed state of the container with the presence of a zone of displacement of the edges in the circumferential welded seam of the body from the viewpoint of the formation of zones of increased stress. This work evaluates the stress-deformed state of the capacitive apparatus under the influence of operating parameters with a different location of the edge displacement zone in the circumferential weld on the apparatus body.

Design and application of hydro-mechanical coupling test system for simulating rock masses in high dam reservoir operations

A meter-level direct shear test system and a true triaxial test system were designed by placing the traditional test apparatus into sealed cabins subjected to high water pressure. The influences of three-dimensional seepage water pressure on the shear and compression deformation of rock mass in Xiluodu Hydropower Station were studied. The test results showed that the changes in water pressure caused obvious shear deformation of the interlayer dislocation zone and tensile deformation and reduction in the triaxial compression strength of the fractured rock mass. The effect of water pressure on shear displacement and tensile displacement had a hysteresis effect. This was consistent with deformation data collected through field monitoring. The deformation mechanism in the reservoir valley was the coupling of the stress and seepage fields caused by reservoir impoundment. The effective stress was reduced, the mechanical parameters were weakened, and the change of the initial stress field led to the slightly overall shear slip and tensile deformation of the bank slope.

Coupled electrochemical-mechanical modeling with strain gradient plasticity for lithium-ion battery electrodes

We first present a model coupling the electrochemical reaction with strain gradient plasticity for a spherical electrode, which aims to analyze the evolutions and distributions of electrochemical-reaction dislocations and diffusion-induced stress during lithiation process. Several critical features viewed by in-situ TEM are incorporated into this model, such as the two-phase boundary and high-density dislocations at the reaction front. It is shown that the microstructure evolution can impact the mechanical properties and electrochemical performances of electrode materials. The results obtained by a finite difference method indicate that, as lithiation proceeds, the circumferential stress on the surface of the lithiated shell changes from compression to tensile stress, which may cause fracture of the active materials. Especially, the electrochemical-reaction dislocation zone results in fairly large stresses at the front of the interface. Furthermore, the lithiation reaction displays a strong size effect, and the movement rate of reaction front reduces as the size of the particles decreases. This work provides a framework for large-capacity, multi-scale research on high-capacity lithium-ion battery electrodes.

Изучение трещинных коллекторов при проведении геологоразведочных работ в северо-восточной части о. Сахалин

During a geological fieldworks in the northeast of Sakhalin Island in order to study the siliceous deposits of the Pilskaya formation and to develop a technique for locating oil deposits in unconventional fractured reservoirs, natural outcrops of Cenozoic deposits on the Schmidt Peninsula and in the Pogranichny depression were studied. Samples were taken for analytical studies (geomechanical, geochemical, lithological, etc.), structural forms (folds, minor faults, slickensides, tension gashes, joints, shear fractures), which are indicators of tectonic deformations of the rock massive, were studied. It is shown that the intensity of fracturing strongly depends on the lithology, the position of the observation point relative to disjunctive and/or plicative structures. The direction of the joints varies depending on the position relative to the elements of the local folds and on the position of the block (with a small-block structure). According to the results of field observations it is shown, that the zone of intense dislocations has an extremely insignificant thickness usually the first tens of meters. An extremely nonuniformity of the stress field in the vicinity of the Pogranichniy depression is noted, which is reflected in the nature of the dipping planes, structural patterns and parageneses. In the northern part of the syncline, numerous flowing oil shows associated with open fracturing are identified, which obviously indicates the extension regime that continues up to this day.

ГЕОДИНАМІКА

Purpose. The purpose of the paper is the reconstruction of the geodynamic development of the shear dislocation zone (shear stress fields) of the Krasnoarmiiska monocline (KM) of Donbas (Eastern Ukraine) and determining the relationships of their impact on the emergence of gas-dynamic phenomena (GDP) in coal sediments. Methodology. Methods of digital geological cartography, mining-geometric simulation, geological-structural analysis, and structural-geomorphological reconstruction are used for the analysis of structural-geological information. A complex of methods for statistical processing of data on the tectonic disturbance is used – estimation of the frequency of azimuth orientations by the roses-diagram method. Techniques of morphotectonic analysis of the coal bed (a mathematical technique for identifying the gradient structures) are applied. Results. A tectonic model of formation of pull-aparts in the mode of transtension on the territory of KM (on the example of “Dobropilska” mine) is proposed, which results in manifestations of GDP (in particular “wet blowers”) in the form of a small kettle of subsidence in zones of en echelon overlapping of shears. The latter ones are formed under the action of the shear field of tectonic stresses (the axis of space shortening is (σ1) due to the horizontal shear is oriented in azimuth 160-170° (340-350°), the axis of elongation is (σ3) – 70-80° (250-260°). At this, the combination of fringing Y and T faultings in the conditions of transtension, most likely, provides gas permeability and water permeability of the zone. Structure-kinematic relationships of formation and development of shear dislocations of KM at Donbas are researched. Originality. The structural-kinematic relationships in the formation and development of shear dislocations of the Krasnoarmiiskyi district of Donbas and their impact on the formation of GDP zones were studied firstly. They based on the developed digital model of the actual tectonic disturbance of the rock massif on the example of the mining allotments group of KM. It is established for the first time: a) subparallel disjunctives of the NE orientation (15-30°), regardless of morphology, are as the boundaries of parallelogram-like blocks, forming either scaly packets or packets of fault scarps (depending on the morphology of the faultings), limited in the strike by the fault planes of N-NE and SW fall; in the case of scaly packets in the orientation of the fall of the fault plane it is dominated by the E-SE direction, the faultings limiting the fault scarps are characterized by the opposite WN direction of the fall; b) faultings of SE orientation are morphologically represented by shear-thrusts, and with depth change not only the angle of incidence from 35° to 85°, but also the azimuth of strike (from 20-25° to 50°), forming a fanlike feathering of the main faulting in the plan; c) faultings of different morphology are represented not by a single fault plane, but by a series of disturbances on all stratigraphic horizons, which form a zone of faulting formation – a vertical "tectonic strip"; d) in the SE part of the mine "Pioner" a duplex of compression (transpression mode) was found, it is expressed by a folded system (F), up to 287 m wide and fragments of sloping, changing the strike of the Novoiverskyi thrusts; e) the zone of tension duplexes located in the chain, which have a characteristic broken-step configuration at the "Dobropilska" mine, to which “wet blowers” are connected with, develops due to local strike (transtension); f) paragenesis of deformations in the study area corresponds to the shear field of tectonic stresses with north-northwest direction of compression and east-northeast tension, in which fault-shear displacement occurs along with the disjunctive breaks. Practical significance. The established relationships of the impact of shear tectonics on the formation of GDP in coal beds are important both by clarifying the mechanism of tectonogenesis and the nature of pull-aparts formation (en echelon zones of tension), and by the possibility of using additional prognostic criteria for searching for accumulations of free methane and its sudden manifestations (GDP) in coal beds. The application of knowledge of these relationships at mining enterprises will allow reducing the costs for the struggle against dangerous GDP manifestations and predicting them reliably.

Plastic Deformation and Electrophysicochemical Treatment of Tubular Medical Concentrator Waveguides

Ultrasonic methods for eliminating vascular obstruction are widespread throughout the world. The advantages of such methods are the absence of surgical intervention, a low probability of complications, and a low cost of treatment. Ultrasonic waveguide systems for the destruction of intravascular formations and elimination of vessel obstruction are made in the form of hollow or continuous long rods of constant and variable cross-section (concentrator waveguides). The development of new methods of treatment based on the use of stepped ultrasonic waveguide systems of a tubular type is underway, allowing to supply fluids to the zone of dislocation of an intravascular formation. The presence of a hollow spherical tip with axial and lateral micro-holes in the distal part of such waveguide systems, designed to influence the resulting cavitation jet, both on the intravascular mass and on the affected area of the vascular wall, allows the vessel to be restored with a simultaneous increase in the elasticity of the vascular wall. Such a combined vibration and shock and cavitation effect is currently one of the most effective methods of treating intravascular formations. An analysis of the sizes, structures and materials for the manufacture of tubular concentrator waveguides shows that their shaping can be carried out by various methods: cold deformation, mechanical, hydroabrasive treatment, using welding (or related processes), electrolytic, and also combined processing methods. The existing processes for obtaining long products of small diameter, based on plastic methods, mechanical processing and physical and technical methods, have a number of disadvantages that do not allow the manufacture of tubular concentrator waveguides with the required characteristics. The paper presents the results of the analysis of literary sources, as well as the results of experimental studies, which have made it possible to substantiate the choice of methods for the step-by-step manufacture of tubular concentrator waveguides: obtaining a tubular stepped element by unrestricted drawing, obtaining a working tip by distributing and crimping, obtaining side holes in the working tip by electrochemical сutting.

Study fatigue crack initiation in TiB2/Al-Cu-Mg composite by in-situ SEM and X-ray microtomography

In this work, the fatigue initiation in a particle-reinforced aluminium matrix composite was investigated. The fatigue cracks mostly initiate at multiple sites associated with TiB2 and second phases (S/θ). Only few cracks initiate from individual TiB2, and they are caused by matrix fracture close to the high density dislocation zones around TiB2. Furthermore, the growth capability of initiated cracks is dependent on their stress intensity factors at crack tip. Only crack initated from largest-sized (S/θ + TiB2) cluster is developed into main crack. During main crack evolution, the small crack grows along slip traces and retarded by grain boundaries and/or TiB2.

Experimental Study on Characteristics of Seismic Damage and Damping Technology of Absorbing Joint of Tunnel Crossing Interface of Soft and Hard Rock

It has generally been believed that the serious seismic damage of tunnel mainly occurred in portal section and fault dislocation zone. However, the survey of seismic damage showed that the seismic damage of tunnel also mainly occurred in geological section at interface of soft and hard rock. Currently, merely scholars have made some research studies on characteristics of seismic damage and damping technology of tunnel crossing the vertical interface between soft and hard rock in high intensity area, and the mechanism of seismic damage has not been clearly revealed. Therefore, based on the Urumqi Metro Tunnel project in China, a three-dimensional six-degree-of-freedom shaking table model test was carried out. Through comparative analysis of peak ground acceleration (PGA), displacement difference at the interface between soft and hard rock, and structural safety factor under 5 kinds of conditions, the seismic damage characteristics of tunnel crossing interface of soft and hard rock were revealed, and a new damping technology of absorbing joint was proposed. The following findings can be drawn. (1) The seismic damage of tunnel is mainly affected by stratum inertial force under the homogeneous stratum of soft rock. The seismic damage of tunnel is mainly caused by the forced displacement (the displacement difference between the two sides of interface of soft and hard rock), followed by stratum inertial force under the geological condition of interface between soft and hard rock. (2) The conventional type of absorbing joint (only the second lining is set with absorbing joint) is used in tunnel lining structure, and the damping ratios of principal tensile stress, bending moment, and axial force of lining are above 47.5%, 40.7%, and 72.7%, respectively. Compared with conventional type of absorbing joint, the damping effect of new type of absorbing joint (staggered absorbing joints of primary support and secondary lining) is 19.9% higher than that of conventional type. (3) The new type of absorbing joint is recommended for tunnel crossing interface section of soft and hard rock. The specific implementation suggestions are as follows: the setting interval of second lining absorbing joint is the same as the length of lining formwork trolley, and the interval of primary support absorbing joint can be set according to excavation footage length. The filling materials in second lining absorbing joint can be shared with the rubber waterstop set in construction joint, and the primary support absorbing joint can be realized by injecting mixtures of rubber particles and shotcrete.

Dynamic recrystallization behavior and mechanical properties of bimodal scale Al2O3 reinforced AZ31 composites by soild state synthesis

Abstract In this paper, (500 nm 1% +5 µm 3%) bimodal scale Al2O3p/AZ31 composites was fabricated by solid state synthesis and the effect of bimodal scale Al2O3 particulates on its dynamic recrystallization behavior and mechanical properties was investigated. The optical microscopy, scanning electron microscopy, transmission electron microscopy and electron universal strength tester composites were used to characterize the composites. The results indicate that the grains size of the composites are significantly refined and the mechanical properties are obviously improved. Due to the presence of the bimodal scale Al2O3 particulates, the high-density dislocation zone is formed around nano-Al2O3p and the particle deformation zone is formed near micron-Al2O3p. These zones are ideal sites for the formation of recrystallization nucleus. Meanwhile, the addition of the bimodal scale Al2O3 particulates may delay or hinder the growth of matrix grain through the pining effect on the grain boundaries, resulting in significantly improving the yield strength and tensile strength of Al2O3p/AZ31 composites.

Comparative Analysis of Friction Stir Welded Joints using Water run and Air stream cooling for Superior Strength

Abstract The present study is focused mainly on the comparative analysis of mechanical properties and microstructure of nitrogen stainless steel using friction stir welding (FSW). Temperature max out is the major factor for quality welding and for this reason water run is used for cooling while welding nitrogen stainless steel and also air stream cooling is used for comparison of strength in the welding. It is found that by using water run cooling in the welding area, the heat affected zone shows superior density in dislocation and nugget zone shows a grain size which is in better-quality when compared to air stream cooling in the joints. In addition to the above tests immersion corrosion test is conducted to analyze how much wear the tool undergone during the welding process and it has observed better corrosion resistance for water run cooling

ПРИМЕРЫ ВЗАИМОДЕЙСТВИЯ ГЕОДИНАМИЧЕСКИХ СИСТЕМ В МОРФОСТРУКТУРЕ СЕВЕРА ВОСТОЧНО-ЕВРОПЕЙСКОЙ ПЛАТФОРМЫ

To determine the nature of the contribution of current tectonic processes to the formation of morphostructural ensembles is an important task. This can be done by comparing the morphostructure with the expected consequences of the impact of geodynamic systems. In the border area of the Baltic Shield and the Russian Plate, within the Circumbaltic zone of dislocations, there is a chain of recent graben depressions. The location of the depressions is determined by the tectonophysical patterns of dislocation sampling and favorable local structural conditions. Depression arose as areas of tension with the superpositional interaction of two subordinate horizontally oriented newest geodynamic systems – pressing the Baltic shield onto the Russian Plate and pushing the geological substrate at the point of their junction in the perpendicular direction. In the northern part of the White Sea Depression, the “visor” of the Karelian massif is approaching to the region of oncoming progressive stretching around the Kandalaksha graben. The superposition of these processes is clearly expressed in relief. Thus, the formation of morphostructures in the area is strongly influenced by the interaction of geodynamic systems.

STRUCTURAL-KINEMATIC EVOLUTION OF THE EARTH'S CRUST OF THE DNIEPER-DONETS PALEORIFT <br/>Part 1. Structural manifestations of reid deformation in sedimentary cover

The article highlights the results of geotectonic studies of postrift complications of the structure of the Dnieper-Donets paleorift. Platform late Hercynian inverse tectogenesis was accompanied by the formation of large shaft-like zones of anticlinal structures against the background of syneclise sagging of the sedimentary basin — the Dnieper-Donets Basin. In the subsequent, Cimeric and Alpine epochs of platform tectonic activation in the geodynamic regime of slow plate compression, collision deformations of the horizons of sedimentary complexes occurred with the formation of secondary deformation structural forms.Using the original technique for reconstructing the fields of tektonic stresses and deformations and tectonophysical analysis of geostructures in the platform cage cover, the structures of reid deformation and their structural ensembles-parageneses of reid deformation, which compose the zones of reid dislocations, were first identified. It is shown that reid tectonics has a regional scale of manifestation and is the main factor in the collisional warpage of horizons and structural reorganization of the sedimentary cover at the inversion stages of the structural-kinematic evolution of the paleoriftic crust.

The Turonian-Coniacian deposits of the south-west of the Ulyanovsk-Saratov trough

Integrated study of a series of the Turonian and Coniacian complete geological records has revealed the stratigraphic completeness and specified the faunal contents of the deposits. The south and the southwest of the Ulyanovsk-Saratov trough have been shown to comprise the thickest beds of the studied interval represented by carbonate and carbonate-terrigenous rocks. Northwards, in the zone of the Saratov dislocations, the Turonian – Coniacian bodies are peculiar for terrigenous and terrigenous-carbonate compositions. The beds are ubiquitously monotonous, which complicates identifications at the stage and the substage levels. Distributions of the benthic foraminifer assemblages and the data on the finds of cephalopods, inoceramus, echinoderms, brachiopods and siliceous sponges have allowed to distinguish detailed biostratigraphic units at the level of biozones traced within the examined structural units. An attempt has been made to reconstruct the conditions in the marine environment.

Decontamination of earthquake catalog from quarry blast events in northern Egypt

Earthquake catalogs are often contaminated by man-made crustal activities such as quarry blasts. That is the case in northern Egypt, where many of cement quarries were working so long time ago since the beginning of the twentieth century (1911). Therefore, it is necessary and essential to separate these quarry blast events from the earthquakes for real seismicity and hazard analysis. Generally, discrimination of quarry blasts from tectonic events often done through different techniques and methods. In this study, the time and frequency-domain analyses of the Egyptian National Seismological Network (ENSN) digital seismograms have performed using three techniques and methods (S/P wave amplitude peak ratio, complexity, and spectral ratio). Moreover, the power of event (Pe) analysis comprising three techniques (S/P wave amplitude peak ratio, complexity, spectral ratio) was also used together to extend the discrimination accuracy as well. Finally, we have used a linear discrimination function (LDF) analysis. A total of 1473 seismic event waveforms (ML ≤ 3.0) from the ENSN digital database have been investigated. The obtained results indicate that for West of Nile Dislocation (zone no. 1) 78.1% of the investigated seismic events are tectonic events; however, 21.1% are quarry events and 0.8% are misclassified events. For the East Nile Dislocation (zone no. 2) 36.2% and 63.7% are earthquakes and quarry blast events, respectively and 0.1% are misclassified events. This means that the earthquake catalog for zone no. 2 in northern Egypt is highly contaminated and needs very high concern during the further treats especially with microearthquakes dataset for actually real seismicity and hazard analysis.

Effect of tool edge radius on material removal mechanism in atomic and close-to-atomic scale cutting

For mechanical cutting, when cutting depth is decreased to atomic and close-to-atomic scale(ACS), the material removal mechanism would be dominated by dislocation motion, different from conventional cutting and nanocutting. It is is greatly influenced by cutting edge radius effect in the aspects of chip formation, cutting forces, and stress distribution, etc. There appear three deformation zones in ACS cutting, including dislocation slip zone, chip formation zone and elastic deformation zone. As cutting-edge radius increases, both of dislocation slip zone and chip formation zone are suppressed while the elastic deformation zone tends to continually grow. When cutting edge radius is increased to be larger than a threshold, the elastic deformation zone is further transformed into one elastic and plastic deformation zone, while a very small chip formation zone, and dislocation zone is remained ahead of rounded cutting edge. Consequently, though the minimum cutting depth is decreased to single atomic layer, the material removal behaviour is also dominated by extrusion action of cutting tool, following the mechanism of nanocutting. The research findings would provide theoretical guidelines to the cutting tool design for atomic and close-to-atomic scale cutting.

Revealing the inhibition mechanism of grain size gradient on crack growth in gradient nano-grained materials

Gradient nano-grained (GNG) materials, in which grain size changes from nano-scale in the surface to micro-scale in the core, have shown superior fatigue property, good strength and ductility. However, crack growth behaviors of GNG materials are studied hardly. In this work, the effect of grain size gradient on crack growth is investigated to reveal the inhibition mechanism of crack growth in GNG materials. The developed model employs a distributed dislocation method to model the evolution of plastic zone. The influence of grain size gradient on the distribution of dislocations in grains and the local stress intensity factor is analyzed. The results show that the sizes of dislocation zone and dislocation-free zone in grains become larger as the gradient of grain size increases. The number of dislocations emitted from the crack tip increases with the grain size gradient increasing, so the shielding effect of emitted dislocations on the crack growth increases and crack blunting becomes more serious. This means that a sharper grain size gradient inhibits the crack growth more effectively. The results in this paper are important for understanding the fracture behaviors of materials with grain size gradient and are helpful for material design and structural optimization.

Assessment of the Seismic Impact of Industrial Explosions in the Central Part of the East European Platform

The attenuation coefficients of longitudinal and shear waves propagating in the Earth’s upper crust below the central region of the East European Platform have been determined using seismic observations along a profile from the Novogurovskii limestone quarry to the Mikhnevo small-aperture seismic array. Assuming that dissipative properties of the Earth’s crust are invariable, we drew a contour map characterizing the propagation of seismic energy generated by open pit mine blasting in the central part of the East European Platform; the map reflects both historical and recent earthquakes as well. The distribution of seismic impacts of industrial explosions is compared with the distribution of zones of tectonic dislocations revealed by lineament analysis. The map also contains estimates of the intensity of open pit blasting in 2013–2017.

Fracture mechanism of nano- and submicron-SiCp/Mg composite during room temperature tensile test: Interaction between double sized particles and dislocations

The microstructure evolution and fracture behavior of Mg-2.7Al-0.8Zn (AZ31B) reinforced with 1 vol% nano silicon-carbide particle (NN-SiCp) and 4 vol% submicron SiCp (SuM-SiCp) during room temperature tensile test were investigated. The tensile failure mechanism of composite in the strain range of 0.8–2.4% were determined using the dislocation studies and microcrack analysis. The addition of double sized SiCp resulted in the extensive accumulation of dislocation near the interface between SiCp and matrix, and the dislocation density is increased as the increase of strain. The formation of high density dislocation zone was identified as one of the main causes of strength enhancement. Some microcracks can be found in the interface between SuM-SiCp and matrix, which show that the high stress concentration exists in the SuM-SiCp/Mg interface due to the particle size and polygonal morphology. However, the bonding interfaces of NN-SiCp/Mg were still continuous, and no microcracks were present around NN-SiCp. As a result of non-deforming SuM-SiCp resisting the crack-propagation, an appreciable crack blunting effect is generated, which contributes to the overall strengthening effect of double sized SiCp/Mg composite.

Assessment of Stress-Strain and Shock Bump Hazard of Rock Mass in the Zones of High-Amplitude Tectonic Dislocations

The paper analyses geodynamic processes in the development of the Talnakh and Oktyabrsk deposits, which have complex geological structure. It demonstrates the results of the forecast estimation of seismic energy released on the contact surface of the fault plane of type I and II tectonic dislocations when stoping approaches. The article discusses the geodynamic processes occurring during the mining of the Talnakh and Oktyabrsky deposits of complex geological structure. The results of predictive assessments of seismic energy released at the contact surface displacement of a tectonic disturbance type I and II at the approach of remediation. For practical use of the obtained graph of the dependence of critical distance from the front of the treatment works to a tectonic disturbance on the magnitude of the angle of internal friction.

The Leba Ridge–Riga–Pskov Fault Zone – a major East European Craton interior dislocation zone and its role in the early Palaeozoic development of the platform cover

The Leba Ridge–Riga–Pskov Fault Zone – a major East European Craton interior dislocation zone and its role in the early Palaeozoic development of the platform cover