The Analysis of the Strength of the Ship’s Hull After Running Aground

The shipping activity seeks to combine various perspectives such as quality, quantity, welfare satisfaction and safety and security prerequisites related to transportation through the port to the waters. However, when sailing, the KM. Dharma Rucitra VII ran aground, causing the heavy steering leaf to be moved and resulting in overload, so the ability of the Thermal Overload Relay (TOR) is needed as an electric motor safety from overload. This study aims to analyze the performance of the Thermal Overload Relay (TOR) as a safety for the electric motor driving the rudder leaf from overload due to the ship running aground. The research uses qualitative methods with data collection techniques in the form of observation, interviews and documentation and then analyzed through three stages, namely reducing data, presenting data and drawing conclusions. The result of the research shows that: 1) The rudder leaf is stuck on the seabed because the ship ran aground, causing the Thermal Overload Relay (TOR) on the rudder panel to work; and 2) Thermal Overload Relay (TOR) on the rudder panel when the ship ran aground works in the current range of 7.5A to 10A.

Effects of repeated rolling of agricultural tractors on soil stress and deformation state in sand and loess

Different types of foundations are used in steel, above-ground cylindrical storage tanks for liquids. If a sand-gravel foundation is used under the entire bottom of the tank or only in the central part of the tank, settlement can be expected, and it increases after many years of operation. The paper presents the typical kinds and types of soil settlements under the bottoms of the tanks, in which different types of foundations were used. Numerical analyses of the effect of the soil settlement on the state of deformations and stresses in steel sheets of the bottom under one of the real tanks, in which different types of foundations and different cases of settlement were assumed. The results of numerical analyses indicated the possibility of evaluating the state of the soil settlement and bottom sheet deformations on the basis of simple measurements of deformations of the lower part of the tank cylinder. These measurements can be very useful in assessing the possible risk of failure of the tank bottom during each period of its operation, as measurements of settlement of the bottom of a filled tank are not feasible in practice. It has been proposed that in each steel tank, the deformation of the cylinder’s sheets should be measured even before the beginning of exploitation, and that in subsequent periodical measurements, the influence of the soil settlement under the tank on the state of the cylinder deformation and bottom’s strain should be assessed more accurately.

Load effect upon soil stress and deformation state in structured and disturbed sandy loam for two tillage treatments

During the assessment of the static strength of the flange connections elements Dn2130 and Dn2080 of the emergency cooling heat exchangers 08.8111.335 SB (TOAR), it was found that there is an excess of the allowable stress values. These calculations of static strength per formed using the finite element method (FEM). The analysis of the static strength of the flange joints was performed taking into account the design values of the tightening of the studs, equal to 22,527 kgf and 8,836 kgf, accordingly. At the same time, one of the main purposes of heat exchangers TOAR nuclear installation (NI) WWER-1000 is the work until accidents. The analysis of accidents of NI WWER-1000 showed that the largest values of change of parameters of environments in heat exchangers of TOAR correspond to accident “LOCA: Bilateral rupture of MCT”. Based on his, we considered the thermal stress state of heat exchangers for this accident. To determine the thermal stress state of the TOAR heat exchanger elements, during accidents of the nuclear installation, strength calculations were performed in the non-stationary formulation of the problem. One of the boundary conditions for these strength calculations is the distribution of temperatures along the thickness and length of the walls of the elements of the heat exchanger, which changes over time. Numerical thermohydraulic calculations were performed to determine these boundary conditions. In the article for the first time the results of calculations of thermal stress state of separate elements of heat exchangers TOAR, for work of heat exchangers during accidents of nuclear installation are received. It is established that the elements of the flange connection Dn2130 are one of the most critical elements of TOAR heat exchangers. To determine the thermal stress state of the heat exchanger elements, analytical thermal calculations, numerical thermohydraulic and strength calculations were performed using the FEM method. As a result of the analysis of the performed strength calculations, it was concluded that it is necessary to reduce the tightening value of the flanges of the flange connection Dn2130 to 14600 kgf

During the assessment of the static strength of the flange connections elements Dn2130 and Dn2080 of the emergency cooling heat exchangers 08.8111.335 SB (TOAR), it was found that there is an excess of the allowable stress values. These calculations of static strength performed using the finite element method (FEM). The analysis of the static strength of the flange joints was performed taking into account the design values of the tightening of the studs, equal to 22,527 kgf and 8,836 kgf, accordingly. At the same time, one of the main purposes of heat exchangers TOAR nuclear installation (NI) WWER-1000 is the work until accidents. The analysis of accidents of NI WWER-1000 showed that the largest values of change of parameters of environments in heat exchangers of TOAR correspond to accident “LOCA: Bilateral rupture of MCT”. Based on this, we considered the thermal stress state of heat exchangers for this accident. To determine the thermal stress state of the TOAR heat exchanger elements, during accidents of the nuclear installation, strength calculations were performed in the non-stationary formulation of the problem. One of the boundary conditions for these strength calculations is the distribution of temperatures along the thickness and length of the walls of the elements of the heat exchanger, which changes over time. Numerical thermohydraulic calculations were performed to determine these boundary conditions. In the article for the first time the results of calculations of thermal stress state of separate elements of heat exchangers TOAR, for work of heat exchangers during accidents of nuclear installation are received. It is established that the elements of the flange connection Dn2130 are one of the most critical elements of TOAR heat exchangers. To determine the thermal stress state of the heat exchanger elements, analytical thermal calculations, numerical thermohydraulic and strength calculations were performed using the FEM method. As a result of the analysis of the performed strength calculations, it was concluded that it is necessary to reduce the tightening value of the flanges of the flange connection Dn2130 to 14600 kgf.

The article concerns the application of the FEM method for the prediction of stress and deformation states in a workpiece during the thread rolling process (TR). The analysis covered a new kinematic variant of the TR process in which the basket of the head rotates and is torque-driven, while the workpiece is stationary and the head with the rollers moves axially relative to the workpiece. The TR process was considered as a geometrical and physical non-linear initial and boundary problem with non-linear, moving, and variable in time and space boundary conditions. The boundary conditions in the contact areas of the tool with the workpiece were unknown. An updated Lagrange (UL) description was used to describe the physical phenomena at a typical incremental step. The states of strain and strain rate were described by non-linear relationships without linearization. New discrete systems of motion and deformation equations of the object in the TR were introduced, which take into account the change in the stiffness of the system during the TR process. This equation was solved by the central differences method (explicit). The material parameters were estimated during tensile tests to determine the characteristics of the C45 steel, and a new semi-empirical method was used to determine the relationship yield stress, effective true strain, and effective true strain rate in the thread rolling process. A modified Cowper-Symonds material model was also used to model the displacement process of the wedge on an elastic/visco-plastic body reflecting the TR process. A non-linear dependency of material hardening module depending on strain and strain rate was introduced. To confirm the plane state of deformation and spatial state of stress, an experimental investigation was carried out. The computer models were validated, and a good convergence of the results was obtained. Applications in the ANSYS/LS-Dyna program were developed to simulate the TR process. The developed applications enable a comprehensive time analysis of the states of displacement, strain, and stress occurring in an object consisting of a workpiece (shaft) and a tool (roller) for the case of a plane strain state and a spatial stress state. Exemplary results of numerical analyzes are presented to explain the influence of the friction coefficient on the condition of the thread quality, and the state of deformations and stresses were shown.

Yielding support, commonly applied to secure dog headings, is made of carrying elements in the form of steel frames and friction props. Yielding capacity of this support is realized in frictional joints, which due to their geometry can be divided to straight and arch joints. Occurring in steel frames arch frictional joints are characterized with more complex loading state than straight joints used in friction props. In the article, there is presented an analysis of the state of stress and deformation of the arch frictional joint, which was carried out on the model of these joints using finite element method. The scope of the analysis included two methods of loading of arch frictional joint, namely its axial compression and bending. In both cases, joints were loaded dynamically with the impact of freely falling mass. Arch joints with and without passive pressure were submitted to an axial compression. Physical model of the frictional joint was developed on the basis of a system applied during the stand tests. To solve mathematical model an explicit integration method was used. As a result of analyses carried out, temporal courses of force transmitted through the frictional joint, and displacements of section sliding down were determined. On the basis of the temporal courses, dependences between maximum value of force transmitted through the frictional joint and the height from which the impact mass falls down were determined. Distributions of reduced stresses in elements of frictional joint were also determined and the state of deformation was described. In order to emphasize the difference between straight and arch frictional joints, also an analysis of internal forces in arch frictional joint depending on its geometrical parameters without and with passive pressure was presented.

The effect of microscopic voids on the failure mechanism of a ductile material is investigated by considering an elastic-plastic medium containing a boubly periodic array of circular cylindrical voids. For this voided material under uniaxial or biaxial plane strain tension the state of stresses and deformations is determined numerically. Bifurcation away from the fundamental state of deformation is analysed with special interest in a repetitive pattern that represents the state of deformation inside a shear band. Both in the fundamental state and in the bifurcation analysis the interaction between voids and the details of the stress distribution around voids are fully accounted for. Comparison is made with the shear band instabilities predicted by a continuum model of a ductile porous medium. Based on the numerical results an adjustment is suggested for the approximate yield condition in this model of dilatant, pressure sensitive plastic behaviour.

Summary The necessary conditions for plastic deformation in ionic solids are readily defined. There must be mobile dislocations in sufficient numbers, on a sufficient number of slip systems for a general strain to take place at the applied strain rate. Provided these conditions are fulfilled an ionic solid may be ductile. In fully ionic solids dislocations are highly mobile on some slip systems at least, down to very low temperatures, whereas in the more covalent solids this is not so. In most ionic solids the number of available slip systems does decrease with fall of temperature, and the multiplication of dislocations by cross-slip also becomes increasingly difficult at low temperatures. We conclude that the necessary conditions for deformation are unlikely to be fulfilled at low temperatures, and this is in agreement with the experimental facts. While these are the necessary conditions for ductility they may not be sufficient ones. As a result of the occurrence of plastic deformation cracks may form in ionic solids. For the material to flow rather than fracture, these cracks, or pre-existing cracks for that matter, must be non-propagating at the stress levels and strain-rates concerned. Here it is more difficult to define the conditions for flow precisely. The relevant factors include the stress state at the head of the crack, and the temperature dependence and the strain-rate dependence of the yield stress of these solids as a function of purity. For polycrystalline materials, a knowledge of these factors, together with the grain-size dependence of the yield stress, should permit some prediction of the transition between ductile and brittle behaviour. At high temperatures, deformation occurs by creep at very low stresses. New mechanisms of deformation appear, in which the movement of dislocations by glide is less important, and at the highest temperatures diffu-sional processes play an important role. Steady-state creep represents a balance between the hardening of the material by deformation and thermal recovery. The onset of recrystallization can lead to a sudden increase in the rate of creep.

This report completes a two-phase project to identify critical combustion technology research and development opportunities which can provide substantial energy savings and other process improvements in major industrial sectors. The major energy intensive industries considered during this project are primary Metals, Chemical, Petroleum and Coal Products, Stone, Clay and Glass, Paper, and Food. The reader will find a discussion of project concepts including an analysis of the needs and justification for each project. Projects recommended for development are documented in a manner which will facilitate rapid initiation of projects by DOE management or others responsible for improving combustion systems. Although an analysis of each project is contained in this report, a detailed development plan coordinating future development activities needs to be established in any follow-on effort. During the second phase of this project, the Phase I research opportunities were further defined and evaluated. Two project areas, namely improved heat flux and reduction in heat losses, are recommended for development which incorporate research opportunities with high potential for success. 3 refs., 5 figs.

The unique impellers of high-pressure hydroturbines are large in size and mass and are manufactured as welded structures, in which the top rim, bottom rim and each blade are cast separately and then welded, or sometimes made as a single piece. Due to the operating conditions of hydroturbines, individual parts of the impeller (blades, lower rim) are made of cavitation- and corrosion-resistant chromium steels. The welded design allows for the production of combined impellers: the parts prone to cavitation are made of stainless chromium steels, the rest are made of cheap low-alloyed ones. Cracks that usually start in places of stress concentration and after brewing appear again after some time. In impellers cast as a whole, fatigue failures also occur during the operation of hydroturbines, they are caused by vibration of the unit as a result of pulsation of the pressure of the water flow, vortex formation, cavitation along with hydroabrasive wear. Fatigue cracks and fractures most often occur at the inlet and outlet edges of the blade, where dynamic loads are superimposed on the constant, maximum static load from the water pressure. The methods of combating cracking, research methods and modeling of the operational load of the blades are considered. Calculations of the fatigue strength of the working wheels made it possible to draw conclusions about their stressed state. Real-life and model experiments were conducted to determine the levels of pressure pulsation in the impellers of high-pressure radial-axial hydroturbines at a head of 300 meters. The results of these studies can be considered as initial data for their further use in calculations of the fatigue strength of the impellers of high-pressure radial-axial hydroturbines in modern 3D models.

On the development of new characteristic values for the evaluation of sheet metal formability

Cylindrical void in a rigid-ideally plastic single crystal. Part I: Anisotropic slip line theory solution for face-centered cubic crystals

The purpose of this article is to perform the calculation of this design for the strength of the sleepers in compression according to the “The Strength and Stability Calculation Rules for Railway Track”, which has not been used before. Wooden sleepers in the subway tunnel are encased in track concrete with 2/3 of their length resting on the concrete base. Under the action of rolling stock, stresses and deformations occur in the upper track structure elements. Their dependence on the forces affecting the track is complicated and hard to define. To solve the strength calculation problem, some prerequisites were assumed, and a design diagram and model were created. The magnitude of the vertical modulus of elasticity of the rail pad of the non-ballast track on wooden sleepers in the subway tunnel, the horizontal modulus of elasticity of the track rail, the dynamic vertical pressure of the wheel on the top of the rail, as well as estimated normal stress in the sleeper under the pad were calculated to determine the vertical forces acting on the rail pad of the intermediate rail fastening. The results obtained from the calculation of the wooden sleeper using the “The Strength and Stability Calculation Rules for Railway Track” showed that its bearing capacity is ensured.