End Sections Research Articles

Micro-X-ray spectral determination of the chipboard dust samples elemental composition

The paper determines the composition of dust from electrostatic precipitators of EAF gas cleaners during long-term storage in dumps in order to obtain information on classifying dust as hazardous waste. Determination of the heavy metals content in waste was performed by atomic absorption flame spectrophotometry on an AAS-1N spectrophotometer. The content of the amount total iron and the determination of its various oxidation states was carried out by redox titration with potassium bichromate in an acidic medium. A comprehensive metallo-graphic study of dust samples included macroanalysis (at x16 magnification), microanalysis of the structure of the end section of pellets from fresh dust from EAF electrostatic precipitators using optical microscopy (x 50, x 500). A detailed analysis of the microstructure of the selected samples was carried out using a JSM-6490 scanning electron microscope in the mode of secondary elastically scattered electrons. The X-ray spectral analysis of the selected samples was carried out using energy and wave spectrometers attached to a JSM-6490 scanning electron microscope. Chemical analysis of dust samples showed that there are no significant differences in the content of total iron in the presented dust samples, although there is some decrease in the depth of the dump. A stronger decrease in the transition from the surface of the dump to the depth is noted by the content of Fe3O4. All samples are magnetic, which indicates a significant content of magnetic nitrous oxide-iron oxide in the dust, most likely in an unbound state. The presence of zinc and lead impurities in the melting charge, evaporating at the operating temperatures of the furnace, leads to their oxidation by the air flow, as a result of which they can be in the final dust both in the form of free oxides and in the form of composite structures with iron oxides. It has been established that the results of the chemical analysis of electrostatic precipitator dust samples, their qualitative composition and the content of toxic heavy metals, in general (according to the average value of 10 determinations) correspond to the given technical conditions of the enterprise for this type of waste, the excess was obtained in terms of the zinc content in all considered iron-containing wastes. A distinctive feature of heavy metals present in the waste is extremely low mobility in buffer media and practical insolubility in water.

Concrete splitting and tip-bearing effect in the bond of anchored bars tested under fatigue loading in the push-in mode: An experimental investigation

The load scenario with a compressive force applied to an anchored bar (push-in mode) has not been sufficiently addressed so far with reference to fatigue, since most of the studies available in the literature are focused on bond behavior under tensile forces (pull-out mode). However, special structures like the towers of wind turbines subjected to alternating moments (and tensile-compressive forces) due to the variable wind direction, are fostering the interest for the fatigue behavior of concrete-bar bond under compressive forces, all the more because several millions of load cycles may be applied. An extensive experimental investigation has been carried out in this research project using a modified beam-end test in the push-in mode. Fifty beam-end specimens were tested under monotonic loads, as well as under low-cycle and high-cycle fatigue loads, with different bar diameters and bonded lengths. The failure modes and bond behavior with the end sections of the anchored bars either unloaded (free ends) or pushing against the concrete (compression ends exhibiting the well-known tip-bearing effect) were investigated as well. The results of the cyclic tests in the push-in mode are compared with those available in the literature in the pull-out mode, through the usual Wöhler curves and fatigue-induced creep curves. Based on this comparative analysis, the failure mechanisms of bond under fatigue loading are identified, with specific attention to the interaction between bond behavior and splitting cracks.

Packing a flexible fiber into a cavity.

The insertion of an elastic rod or fiber into a confining cavity is studied. Such an insertion is a feature of a variety of problems, including packing and unpacking of DNA in viral capsids and the insertion of catheters during surgery. We consider a simplified geometry in which the container is a smooth (frictionless) circular cylinder of radius a. The fiber is pushed through a hole in the curved surface of the cylinder and is then assumed to stay in a cross-sectional plane perpendicular to the cylinder axis. A solution is found for the fiber shape in which most of the fiber lies against the curved interior surface of the cylinder, apart from the final end sectionof the fiber, of length 2.0888a, which crosses the interior of the cylinder before ending at the opposite side, which it meets at an angle 1.15rad to the normal. The force required to push the fiber into the cylinder is EI/2a^{2}, where E is the fiber's Young's modulus and I its cross-sectional moment of inertia. The shape of the final end sectionof the fiber is confirmed by experiment.

Features to Prevent Failed Hardware Colorectal Anastomoses in Laparoscopic Rectal Resections

The aim of research was to study proper results of laparoscopic anterior rectal resection using intraoperative measures to prevent failure of hardware colorectal anastomoses in patients with rectal tumor.Material and methods. Out of 68 patients included in the study, colorectal anastomotic leakage occurred clinically only in 2 cases (2.9%, class A and B) and required no further surgical interventions. When evaluating the risk of colorectal anastomosis failure in each specific case, it is necessary to consider pre- and intraoperative risk factors. Formation of colorectal anastomosis with one angular end of the rectal stump followed by immersion; additional strengthening of the anastomosis zone with interrupted serous-muscular sutures; adequate drainage of the pelvic cavity (the most effective - transperineal presacral) are intraoperative methods that reduce the risk of failed hardware colorectal anastomoses.Results. Out of 68 operated patients, colorectal anastomosis failure occurred clinically only in 2 cases (2.9%, class A and B) and did not require repeated surgical intervention. When assessing the risk of colorectal anastomosis failure in each specific case, it is necessary to take into account pre-and intraoperative risk factors. Formation of a colorectal anastomosis with one angular end of the rectal stump, followed by its immersion; additional strengthening of the anastomosis zone with nodular serous-muscular sutures; adequate drainage of the pelvic cavity (most effectively - trans-interventional presacral) - intraoperative methods that reduce the risk of failure of hardware colorectal anastomoses.Conclusion. Reasonable doubts in the intraoperative evaluation of the blood supply to the end section of the descending colon, viability of the colorectal anastomosis, presence of 3 or more risk factors, low position of anastomosis (less than 10 cm from the outer end of the anal canal) indicate the necessity to form preventive transversostomy.

Numerical calculation of grinding wheel wear for spiral groove grinding

Due to its good cutting performance in titanium alloy machining, integral end mills are more and more used in machining aero-engine impeller blades. The tool spiral groove plays the role of chip acceptor and chip removal, and the accuracy of its parameters has an important effect on the cutting performance. In the grinding process of the spiral groove, the grinding wheel’s external grinding is mainly involved in the grinding task. The grinding wheel’s wear degree is related to the grinding time and grinding times of the grinding wheel, and the wear of the grinding wheel will lead to the change of the parameters of the spiral groove. To achieve the accurate solution of the grinding wheel surface wear profile, image processing technology was used to extract the spiral groove end section contour coordinates of the grinding wheel and fit them. The worn sand profile was solved based on the contact line principle, and the grinding wheel wear amount was obtained. The traditional reconstruction method was used to verify the algorithm. The results show that the accuracy of the reverse algorithm for the wear profile of the grinding wheel is relatively high.

METHOD TO GENERATE ACCURATE ELASTIC AND HYPERELASTIC UNIAXIAL TENSION STRESS–STRAIN DATA WITHOUT AN EXTENSOMETER

ABSTRACT Uniaxial tension tests on dumbbells are routinely used to determine the stress–strain response of engineering materials. The simplest way to calculate strain is from grip displacement during extension, but this introduces significant error when dumbbells are gripped at the wider end sections to avoid the sample breaking prematurely in the grips. Mechanical and optical extensometers alleviate this problem by directly measuring strain in the gauge section. However, the equipment introduces significant additional hardware and software costs, and some experimental setups obstruct or prevent direct measurement of strain. The strain following systems also struggle both with the loss in mark intensity and changes of the shape of the marked point as the strain level is increased. To address these shortcomings, a novel analytical model to correct stress–strain data based on grip displacement is proposed. The model is implemented in Fortran and applied to hyperelastic materials which are assumed isotropic, but in principle the method is not restricted to elastomers. The model is validated with three studies on dumbbells: (i) a finite-element analysis for strains up to 660%; (ii) an experimental test with unfilled natural rubber up to 300% strain using a video extensometer; and (iii) a high temperature experimental test to fracture where the strain is corrected for a filled rubber. The model errors range from 2.2% to 3.1%, which is well within material and experimental uncertainties; hence, the model provides an accurate, inexpensive means of determining stress–strain behavior from grip displacement.

Research on the Application Performance of the Helmholtz High-Efficiency Wave-Elimination Chamber in Gas Wave Tubes

A gas wave refrigerator is a device that uses gas pressure to expand and refrigerate; the moving shock wave in the gas wave tube is the key to cooling. If the shock wave is reflected to the open mouth of the gas wave tube, it will heat the expanded refrigeration gas at the open end, severely reducing the refrigeration efficiency. In order to reduce this effect, a Helmholtz middle wave chamber-type gas wave tube is presented here. This study describes the performance of this structure in the gas wave refrigeration process. The refrigeration performance of the structure’s gas wave tube use was evaluated experimentally and numerically using computational fluid dynamics (CFD). The function of the middle wave elimination chamber was studied and explained: the chamber turns the reflected shock wave back to the end section of the tube and converts part of the incoming shock wave to an expansion wave, which may counteract the reflected shock wave by escaping from wave elimination chamber. The experimental results showed that the structure increased refrigeration efficiency by about 2.9% (50 Hz), 2% (40 Hz), and 2.2% (25 Hz) at the corresponding ejection frequencies, and reduced the reflected shock wave intensity by 11%, which proves the high-efficiency energy dissipation performance and the significant increase in refrigeration efficiency of the Helmholtz-type gas wave tube.

Mechanical properties of plate type steel bar connectors for prefabricated concrete structures

This article presented experimental studies on mechanical properties on Plate Type steel Rebar Connector (PTRC), which is composed of steel plate, thread coupler, and steel tube. This is a new method of mechanical connection of steel bars provided in this article for full-precast concrete shear wall structures. The proposed PTRC was tested under monotonic tensile tests, high-stress cyclic tests and high-deformation cyclic tests according to the code (JGJ107-2016). PTRCs were evaluated as Grade I splice through U0, U4, U8, Asgt, and U20 according to the code. The stress distribution curves and end section rotation of PTRCs with different parameters were analyzed using verified Finite Element Model. The calculation methods of PTRC initial stiffness, including stiffness of bolt and threads were provided.

Инжекционные регуляторы расхода без диффузорных выходных участков

The paper presents the results of theoretical and experimental substantiation of the use of injection fl ow regulators with a new form of fl ow part. A distinctive feature of the structures is a complete change in the end section of the regulator. The output cross-section of the transit water outlet is placed in the downstream and has a diaphragm with edges cut down the stream and partial lateral fl ow clamping. There is no diffuser at the end section, the output of the fl ow into the volume of the downstream takes place directly from the prismatic mixing chamber, which has a constant area. A method for theoretical calculation of hydraulic parameters of injection fl ow regulators with a diaphragm without diffuser output areas has been developed. The validity of the use of theoretical dependencies to determine the hydraulic characteristics of the structure and the effectiveness of the proposed changes in the form of the fl owing part have been proven. Injection regulators without diffusers are capable of taking up to 30% of the excess from the downstream fl ow and ensuring its circulation between the outlet section of the outlet and the mixing chamber. The increase in the regulating capacity compared to existing designs of injection water outlets is due to the optimization of the diaphragm design.

The analysis of asbestos-cement shell pile performance under off-center loading and forced torsion

The paper discusses the new design of a round pile with a relatively smoother surface, developed in an attempt to eliminate excessive negative friction forces. A theoretical study has been conducted into the performance of asbestos-cement shell pile exposed to off-center loading, which occurs in response to uneven deformations in the surrounding soil and seismic loads. The cross section of the upper eccentrically compressed part of a flexible asbestos-cement-pipe-concrete pile element is considered. When considering the stress-strain state of flexible eccentrically compressed asbestos-cement-pipe-concrete piles, the premise of compliance with the hypothesis of flat sections is accepted. With the predicted intensive development of loading friction forces, a method is proposed for preliminary turning these round piles around the axis to remove the main part of the adhesion between the side surface of the pile with the base soil. Theoretically, the stress-strain state of the indicated pile, which is formed during its torsion around the axis, was estimated. The pile is considered as a composite element consisting of a concrete cylinder and an asbestos-cement pipe. As a first approximation, we assume that there are no body forces, and the concrete core and the asbestos-cement shell are rigidly linked. According to the Saint-Venant principle, it can be considered that for a twisted rod at a sufficiently large distance from its ends, the stresses depend on the torque and do not depend on the method of distribution of the forces that give this moment over the end sections. Based on the basic equations of the theory of elasticity, it follows that in a pile of circular cross section, bounded by a concentrically round shell, the cross sections remain flat during torsion.

A coupled CFD-DEM numerical simulation of formation and evolution of sealing zones

Lost circulation can be one of the most troublesome situations during drilling, especially in naturally fractured formations. This situation may lead to serious economic losses because of the loss of expensive drilling fluid into the formation and nonproductive time spent on regaining drilling ROP. Granular lost circulation materials (LCMs) are the most commonly used to prevent and cure lost circulations. However, poor understanding of how granular LCM works at a micro-scale has limited their effectivity. In this paper, we developed a coupled CFD-DEM model by combining computational fluid dynamics with discrete element methods to simulate the sealing process of LCM in a wedge-shaped fracture by tracking the motion of each individual particle. Formation and evolution of both the sealing zone and the resulting force chain network were investigated by combining micro process visualization and analysis of flow characteristic curves of LCM suspension injection. The results show that injected LCM particles eventually result in three situations after transport in the fracture, depending on their size and concentration: 1) no bridging no sealing, 2) bridging without sealing, and 3) bridging with sealing. The fracture sealing zone is formed by either single-particle bridging or dual/multi-particles bridging of LCMs. A successful sealing comprises four stages: 1) LCM suspension uniform flow, 2) unstable bridging, 3) sealing zone formation and growth, and 4) fluid flow through the porous sealing zone. These situations and evolutionary stages are clearly reflected in the morphological changes of the flow curve. The formation and evolution of the force chain network also include four stages: 1) discrete force chain dynamic initiation, 2) small force chain network unstable formation, 3) discrete force chain network aggregation, 4) force chain network stable propagation. Strong force chains are in the front section and weak force chains are in the middle and end section of the sealing zone. The formation and collapse of force chains within bridging particles determines if a bridging structure and a sealing zone can be formed and stable. Dual-particles bridging formed sealing zone is weaker than single-particle bridging one because of the weak point in the strong force chain in the fracture width's direction. This research provides a better insight into the process of fracture sealing by granular LCMs, which contributes to improve efficiency of lost circulation control jobs.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ РАСПРОСТРАНЕНИЯ ВИБРАЦИЙ В ТОНКОСТЕННЫХ КАРКАСИРОВАННЫХ КОНСТРУКЦИЯХ. 2. КОНЕЧНО-ЭЛЕМЕНТНЫЕ МОДЕЛИ И ЧИСЛЕННЫЕ ЭКСПЕРИМЕНТЫ

Based on the refined S.P. Timoshenko shear model, one-dimensional finite elements for modeling the dynamic response of flat rods with clamped section of finite length on one of the front faces have been constructed. To analyze their stationary dynamic response under harmonic external action, a system of resolving equations in a complex form is formed. Three models of kinematic conjugation of clamped and free sections of rods are developed using the equation of connection between the rotation angle of the cross section and axial displacement at the boundary between the marked parts of the rod, the transitional finite element, and the concept of a single finite element with nodes located on one of its front faces. It is noted that for practical implementation, the most convenient model is one that uses a single finite element to represent fixed and free sections of the rod. On the basis of the noted model, a finite element solution of the problem of transverse bending vibrations of a cantilevered flat rod under vibration loading conditions by a periodic axial force applied to the end section of a clamped section of finite length, as well as the problem of transverse bending vibrations of a flat rod with two free ends and clamped length section between them under vibration loading by a transverse force on one of the free ends of the rod was found. The results of the finite element solution of the noted two problems are in good agreement with the previously obtained exact analytical solutions found on the basis of the S.P. Timoshenko shear model. The presence of a significant transformation of the parameters of the stress-strain state of the considered rods during the transition through the boundary from free to the clamped length areas on one of the face surfaces is noted.

Оценка пропуска минимальных расходов воды сооружениями дюкерного типа мелиоративных систем

Issues related to the design and hydraulic calculation of the transit part of a closed tubular water supply structure of the siphon type is considered. The operating conditions of the siphon with rectangular pipes in the transition mode are evaluated, in which the entrance section of the pipes of the culvert structure experiences increased hydrodynamic loads, often leading to certain destructions. The siphon design was modeled with two breaks along the length with a smooth inlet head and without a head. During the experiments, the absence of infl uence of the inlet head of the tubular HTS on the length of the free-flow section was noted. It has been established that the conditions of formation and features of the hydraulic operation of the siphon in the transient mode are largely determined by its design features. With the flooding of the inlet head, the flow of air into the pipe is hindered and a transition mode of the second type is formed with a slight fluctuation of the water level in the upper pool. The dependence of the location of the point of separation of the flow with a decrease in the passing water flow rate on its value is revealed, which made it possible to obtain a graph of the dependence of the relative length of the non-pressure end section on the square root of the Froude number. A comparison was made with the results of studies by other authors, which showed an increase in the relative length in tubular HTS of the siphon type in sections with reverse slopes at the same Froude numbers. Recommendations are given on the methodology for carrying out hydraulic calculation of tubular structures of the siphon type with minimal flow rates.

New technical solutions in the field of protection and fastening of mine workings

The article discusses the features of fastening preparatory workings in difficult geological conditions, which are studied in three directions: improving concrete, arch and anchor fasteners with the consideration of the initial physical and mechanical properties of the rock mass; introduction of steel-polymer anchor; improvement of cast strips designs in combination with arch and anchor fasteners for reuse. Protection methods of mine workings and means of fastening often do not correspond to the peculiarities of the manifestation of rock pressure at the end sections of lavas and in zones of tectonic disturbances, as a result of which can become the main cause of the unsatisfactory state of the mine workings. Mathematical modeling of the rock massif stress-strain state has been carried out by the finite element method. Rigid and pliable cast strips, various technologies for erecting a cast strip, as well as a combination of cast strips with anchor and arch fasteners are modeled. The locations and sizes of rocks destruction zones, stresses in the rock mass for different options of fastening have been determined. The drawbacks of the existing technologies for the construction of cast strips are revealed and the factors for increasing their technical efficiency are established.

New advanced manufacturing process for rear fuselage sections of highly integrated aerospace structures

CS2-LPA-IADP-WP1.2.5. Advanced Rear End Manufacturing is an European project, inside of the CleanSky2 research program of the European Union Horizon 2020 (Grant Agreement nº 945583). This work package focuses on design, manufacturing and testing of new technologies for the manufacturing of aeronautical structures, integrating different elements, at the rear end of an aircraft. The work presented here shows the manufacturing process developed to obtain a full-scale demonstrator of a rear end section of the fuselage in prepreg carbon fiber composite material, integrating stiffeners, contour frames and skin in one-shot. The omega section stiffeners are made by automatic lay-up and forming, integrate them fresh into the demonstrator. The contour frames are also automatically lay-up and formed, carrying out a semi-curing cycle (for which a manufacturing test campaign has been necessary and different curing degree studies). The integration of these semi-cured frames in the demonstrator combines the advantages of a cobonded integration (without rivets) and the simplification of the tools respect to fresh elementals, since the final thickness has already been consolidated. The automatic lay-up of the skin is carried out on a tool where the fresh stiffeners and the semi-cured frames are located. Finally, the curing cyle is done in the autoclave, obtaining the full-scale highly integrated fuselage demonstrator. All the technologies developed in this demonstrator allow automation within an industrial environment with high production rates. 

Optimization of two support spindle shaft on nonlinear elastic supports by rigidity characteristics

One of the main structural elements of metalworking machines is the spindle assembly (spindle), which is used to hold cutting tools or workpieces. The rigidity of the spindle assembly plays a decisive role in ensuring the accuracy and efficiency of the machine as a whole. The assessment of the spindle shaft stiffness is carried out on the basis of the analysis of the static bending of the spindle shaft, which made it possible to formulate and solve the problems of optimizing the spindle shaft according to the stiffness characteristics for two supporting structures on nonlinear elastic supports. To determine the stiffness of roller bearings, the work uses the dependence obtained on the basis of solving the problem of contact interaction of an elastic steel cylinder with curvilinear elastic steel half-spaces. For the considered design scheme, the optimization goals were chosen for the conditions of the smallest displacement of the end section of the spindle shaft console, the achievement of the minimum angle of rotation in this section or the minimum of their normalized superposition, which ensures maximum rigidity in the processing zone. Consideration has also been given to minimizing the swing angle at the front support to maximize bearing life. Mathematically, the problem is presented in the form of minimizing one of the 4 proposed objective functions by changing the variable parameters - the length of the cantilever and the value of the inter-support distance, represented as dimensionless quantities - the cantilever coefficient and the inter-support distance coefficient. Minimum and maximum values ​​of the cantilever length and shaft span were considered as constraints on the variable parameters. Varying the console coefficients and the inter-support distance was carried out by the method of sequential enumeration within the specified constraints, the solution of optimization problems is presented in a graphical form. The solution to the problem of shaft bending was carried out on the basis of the equation of the bent axis of the beam in the framework of the Euler - Bernoulli hypotheses and presented in an analytical form together with analytical dependencies for calculating the radial stiffness of a roller bearing as a function of the supporting force acting on it. The algorithm for solving optimization problems is implemented in the MatLAB package. Optimal solutions have shown that the minimum of the combined functions, consisting of the sum of the relative deflection values ​​at the end of the console and the angles of rotation at the end of the console and on the front support, is achieved at the same variable parameters as the minima of the angles of rotation at the end of the console and on the front support. The proposed approach to the design of the shafts of spindle units of metal-cutting machines, which are optimal in terms of rigidity characteristics, forms a tool for a reasonable choice of bearings and design parameters of spindle shafts.

Comparison of Failure for Thin-Walled Composite Columns.

The novelty of this paper, in relation to other thematically similar research papers, is the comparison of the failure phenomenon on two composite profiles with different cross-sections, using known experimental techniques and advanced numerical models of composite material failure. This paper presents an analysis of the failure of thin-walled structures made of composite materials with top-hat and channel cross-sections. Both experimental investigations and numerical simulations using the finite element method (FEM) are applied in this paper. Tests were conducted on thin-walled short columns manufactured of carbon fiber reinforced polymer (CFRP) material. The experimental specimens were made using the autoclave technique and thus showed very good strength properties, low porosity and high surface smoothness. Tests were carried out in axial compression of composite profiles over the full range of loading—up to total failure. During the experimental study, the post-buckling equilibrium paths were registered, with the simultaneous use of a Zwick Z100 universal testing machine (UTM) and equipment for measuring acoustic emission signals. Numerical simulations used composite material damage models such as progressive failure analysis (PFA) and cohesive zone model (CZM). The analysis of the behavior of thin-walled structures subjected to axial compression allowed the evaluation of stability with an in-depth assessment of the failure of the composite material. A significant effect of the research was, among others, determination of the phenomenon of damage initiation, delamination and loss of load-carrying capacity. The obtained results show the high qualitative and quantitative agreement of the failure phenomenon. The dominant form of failure occurred at the end sections of the composite columns. The delamination phenomenon was observed mainly on the outer flanges of the structure.

STRENGTH OF SHIPS’ GRILLAGES UNDER LATERAL LOAD AND IN-PLANE COMPRESSION

The paper deals with strength of a grillage loaded by lateral load and in-plane compression load (in one direction). It consists of a system of prismatic girders crossing under 90°. The compression load is taken by the longitudinal girders that are elastically fixed on rigid supports. The system of aggregated differential equations is derived for solution of the problem using the Lagrange method. It allows for replacement of the system of aggregated differential equations by a system of independent differential equations. These equations for the case of simultaneous action of lateral and longitudinal compression load have the form of differential equations for bending of prismatic girders laying on elastic foundation and loaded with lateral and longitudinal compression forces. When only lateral load exists, the form of these equations coincides with the form of differential equations for bending of girders laying on elastic foundation and loaded with lateral load alone. When only longitudinal compression load exists, the form of these equations coincides with the form of differential equations for buckling of girders laying on elastic foundation.
 Solutions are given for bending of a grillage (the first two problems). Formulas are derived for calculation of the parameters of longitudinal girders’ bending when girders’ end sections are elastically fixed. Also, formulas are derived for calculation of the reaction forces at cross-points of transverse and longitudinal girders. When only longitudinal compression load exists (third problem), a solution is given for the connection between the coefficient of elastic foundation’s rigidity and the Euler force. Results obtained by using the proposed method are compared with FEA simulations.

A patient with Crohn’s disease – from diagnosis to therapy onset. Therapeutic standards vs. reality – a case report

Crohn’s disease is a nonspecific inflammatory bowel disease. The first symptoms tend to be non-specific, which can cause diagnostic difficulties. Full-thickness inflammation of the bowel wall, which may involve any part of the gastrointestinal tract, is a landmark of this disorder. Terminal ileum is the most commonly affected area, as also described in the presented case. Surgical treatment should be as least invasive as possible due to the high probability of another surgical intervention. We present a case of a patient previously repeatedly treated for anal abscess in an outpatient setting in the USA. The patient was admitted to the surgical ward due to perineal phlegmon in the course of recurrent anal abscess. He was qualified for abscess incision. During hospital stay, the patient developed symptoms of gastrointestinal bleeding. Diagnostic endoscopy of the large bowel revealed macroscopic lesions typical of Crohn’s disease. Repeated attempts to transfer the patient to a unit specialised in the treatment of inflammatory bowel diseases (IBDs) have been unsuccessful. Due to the deteriorating general condition and progressive anaemisation, the patient was qualified for surgery. The end section of the ileum was resected and an end ileostomy was created. After stabilisation of the general condition, the patient was discharged home having been recommended to continue treatment in a gastroenterology clinic, in a centre specialised in the treatment of inflammatory bowel diseases.

THE ASPECTS OF ALMG6 ALUMINIUM ALLOY DEFORMATION UNDER EXPLOSIVE WELDING

The paper presents the results of a study of the features of the deformation of the main plate made of AlMg6 in the process of explosion welding (with corrosion-resistant steel 08Cr18Ni10Ti). It was found that the end and edge sections of the main plate undergo severe deformation, as evidenced by the constructed maps of the distribution of residual deformations over the plate area. With an increase in the detonation velocity, an intensification of the deformation process occurs, which leads to the appearance of cracks and local spalling of plate fragments. In addition, the results of measurements of the elongation of the main plate showed that a noticeable longitudinal deformation of the plate begins approximately at a distance equal to 2/3 of the total length of the plate. The measured value of the beginning of elongation (240 ± 10 mm) with an accuracy of 95% converges with the calculated value (229 mm).