Calculation of temperature and thermoelastic stresses in backups with collars of the unit of combined continuous casting and deformation in steel billets production. Report 2

The problem statement and boundary conditions for calculation of axial thermoelastic stresses in backups with collars of the unit of combined continuous casting and deformation are provided for production of three steel billets. The scheme of calculations for determination of thermoelastic stresses in backups with collars in known temperature field was stated using ANSYS software. The results of calculation of thermoelastic stresses in shaped dies were performed in four sections of a backup with collars. In each section, calculation results are given for four typical lines and seven points. Values of axial thermoelastic stresses for seven typical points of each section are given for the contact surface of a backup with collars and the contact layer at a depth of 5 mm from the contact surface. The stress state of a shaped backup in the middle of depression between the middle collars was determined and the regularities of distribution of axial and equivalent stresses over the thickness, length and width of a backup were established during slab compression and at idle. The results of calculation of thermoelastic stresses in the top of the middle collar of a shaped backup on the contact surface and in the contact layer during slab compression and at idle are presented. Graphs of thermoelastic stresses distribution along the line passing through the top of a collar are given, which show the zones of compressive and tensile thermoelastic stresses during slab compression and at idle. The character of the stress state in the base of extreme collar was determined for production of three steel billets in the unit of combined process of continuous casting and deformation.

Calculation of temperature and thermoelastic stresses in backups with collars of the unit of combined continuous casting and deformation in steel billets production. Report 1

The article describes the main loads affecting shaped backups of the unit of combined process of continuous casting and deformation in billets production. Importance of determining the temperature fields and thermoelastic stresses in shaped backups with collars is provided at formation of several billets, at slab compression and at idle during water cooling of backups. The authors describe strength and thermophysical properties of steel from which the backups are made. Geometry of backups with collars used for obtaining billets of three different shapes in one pass is shown. Initial data of the temperature field calculation are given for backups with collars of the combined unit. Temperature boundary conditions are considered for calculation of temperature fields of backups with collars. Boundary conditions determining temperature of such backups are described and values of the heat flow and effective heat transfer coefficient are given. The results of calculation of temperature fields are performed in four sections and are given for typical lines and points located on contact surface of backups with collars and in contact layer at depth of 5 mm from the working surface. The sizes of finite elements grid which is used at calculation of temperature field of backups with collars are provided. Temperature field of backups with collars is determined on the basis of solution of unsteady thermal conductivity equation corresponding initial and boundary conditions. Values and regularities of temperature distribution in bases and in tops of the middle and extreme edges of the shaped backups are presented during slab compression and at idle when obtaining billets of three shapes in one pass at the unit of combined continuous casting and deformation.

EFFECTS OF NIOBIUM-DOPING ON THE DIELECTRIC AND SWITCHING PROPERTIES OF BARIUM TITANATE CRYSTALS

В работе представлены результаты исследований диэлектрических свойств, процессов переключения и доменной структуры ниобийсодержащих кристаллов титаната бария. Показано, что существенную роль в поведении доменной структуры кристаллов BaTiO:Nb : Nb играет примесь ниобия Nb, ионы которого замещают Ti и изменяют ионный состав решетки. При изменении температуры со скоростью порядка 0,3 К⋅с механически свободных кристаллов BaTiO : Nb в отсутствие внешних электрических полей, процессы перестройки доменной структуры происходят под воздействием внутренних термоупругих напряжений ~ 0,7 МПа и деполяризующих полей ~ 20 кВ-м. This paper reports the results of investigations of dielectric properties, switching processes and the domain structure of niobium-containing barium titanate crystals. It was shown that an impurity of niobium Nb, whose ions replace Ti and change the ionic composition of the lattice, is important for behavior of the domain structure of BaTiO: Nb crystals. At a change in temperature (0,3 К⋅с ) a transformation of the domain structure occurs in the BaTiO: Nb crystals under the influence of the internal thermoelastic stresses ~ 0,7 MPa and the depolarizing fields ~ 20 kV/m.

Stresses modeling in multilayer semiconductor structures of automobile regulators and predicting the reliability of their operation

The problems of increasing the reliability of microelectromechanical systems are considered on the example of an automobile voltage regulator. A model of the process is proposed and a study of the effect of temperature on the formation of stress fields in semiconductor structures of active elements of the controller is carried out. The studies assumed of a possible reason for the change in the parameters of the regulator due to the appearance of defects in the crystal structure of the semiconductor material in the structures of integrated voltage regulators. For the study, a mathematical model was proposed that describes the behavior of a semiconductor element of a real car voltage regulator. It was found that the distribution of stresses in the structures is uneven and the maximum value of stresses reaches the edges., An increase in temperature gradients in the structures of regulators leads to the formation of dislocations that change the electrical characteristics of devices. As a result of modeling, it has been established that thermoelastic stresses arising in the process of manufacturing and functioning of semiconductor structures of a regulator in regulators of this type can cause a change in the structure of a semiconductor device due to relaxation of elastic stresses at dislocations. in cars. Measures are proposed, including thermostating of the sensitive elements of microelectromechanical structures, which will increase their service life.

Stressed state of striker – bimetall system at production of three-layer steel bimetallic strips in the unit of continuous casting and deformation

The article presents the initial data for calculation of stress-strain state of a three-layer bimetallic strip. The regularities of distribution of axial and tangent stresses in the zone of cyclic deformation are considered. The main loads acting on the mold strikers are described for the unit of combined continuous casting and deformation at production of steel three-layer bimetallic strips. The authors describe the method for determining total stresses in the installation strikers from the efforts of compression and temperature loads. Also temperature boundary conditions for determining the temperature fields are considered. The procedure for determining temperature fields and thermoelastic stresses in the strikers is shown using the ANSYS package. The calculation results of temperature fields and thermoelastic stresses were made in five sections of the striker and are given for characteristic lines. The nature of temperature distribution over the thickness of the striker is shown when it is cooled with water at idling and in contact with a bimetallic ingot during its compression. For the calculated temperature fields, the authors have determined the axial and equivalent stresses occurring in the strikers without channels when the ingot is compressed and cooled with water during idling. The magnitudes and patterns of distribution of total axial stresses from the compression and thermal loads are also given along the thickness of the contact layer, along the height and thickness of the strikers.