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EN
The technology of renewal of metal corrugated structures allows efficient and economical reconstruction of existing reinforced concrete structures by the method of encapsulation. However, such structures can be exposed to adverse temperature effects that in combination with traffic loadings could influence the operational reliability of the structures. This article deals with the method of evaluation of the stress-strain state of a three-layer cylindrical structure. The technique is based on the thermo-elasticity theory. The study is performed in two steps: determining the temperature field of a structure, and then calculating the temperature stresses and deformations. As a result of calculations, it was established that the level of temperature field and stresses in a three-layer structure caused by the maximum and minimum ambient temperatures can reach a significant level.
PL
Technologia wzmacniania istniejących żelbetowych obiektów inżynierskich elementami z blachy falistej umożliwia ich sprawną i ekonomiczną naprawę. Niemniej jednak, takie konstrukcje mogą być narażone na niekorzystne oddziaływanie temperatury, co w połączeniu z obciążeniem ruchem może wpływać na ich niezawodność. W artykule przedstawiono metodę wyznaczenia stanu naprężeń i odkształceń w trzywarstwowej konstrukcji o przekroju kołowym. Przedstawiona metodologia jest oparta na teorii termosprężystości. Praca została podzielona na dwa etapy: określenie pola temperatury w obrębie konstrukcji, a następnie obliczenie naprężeń termicznych i odkształceń. W wyniku obliczeń ustalono, że wartości pola temperatury oraz naprężeń wywołane w konstrukcji przez wpływ maksymalnych i minimialnych temperatur otoczenia mogą okazać się istotne.
EN
The current passed by the stator coil of the permanent magnet synchronous motor (PMSM) provides rotating magnetic field, and the number of turns will directly affect the performance of PMSM. In order to analyze its influence on the PMSM performance, a 3 kW, 1500 r/min PMSM is taken as an example, and the 2D transient electromagnetic field model is established. The correctness of the model is verified by comparing the experimental data and calculated data. Firstly, the finite element method (FEM) is used to calculate the electromagnetic field of the PMSM. The performance parameters of the PMSM are obtained. On this basis, the influence of the number of turns on PMSM performance is quantitatively analyzed, including current, no-load back electromotive force (EMF), overload capacity and torque. In addition, the influence of the number of turns on eddy current loss is further studied, and its variation rule is obtained, and the variation mechanism of eddy current loss is revealed. Finally, the temperature field of the PMSM is analyzed by the coupling method of electromagnetic field and temperature field, and the temperature rise law of PMSM is obtained. The analysis of this paper provides reference and practical value for the optimization design of PMSM.
EN
The paper analysed the influence of current frequency on the thermal field of the insulated busbar. Its physical model consists of two hollow cylinders and a solid cylinder with different material properties. In turn, the mathematical model is a system of heat conduction equations with the appropriate set of the boundary, initial and continuity conditions. The problem was solved using the modified Green’s method. As a result, the following characteristics and parameters of the busbar were determined as a functions of frequency: heating curves, local time constants, steady-state current ratings, and stationary temperature profiles. The results were positively verified by finite element method.
EN
An electric turnout heating (ETH) system is an essential technical and economic issue. Uninterrupted operation of the turnouts is crucial to maintaining railway transport safety. The classic heating system is characterized by high energy consumption. The usage of it is extremely expensive, so the need to optimize the current system becomes more and more critical. At the same time, the progress in the contactless heating method has become a promising alternative. The paper presents the results of tests performed for electric turnout heating systems for two types of heaters. In the first place, the analysis of heat distribution was performed using the ANSYS Fluent v.16. The temperature fields in the turnout models filled with a model of semi-melting snow were analyzed. Thanks to cooperation with the Railway Institute in Warsaw the second stage of the research was possible to be completed. In this part, the models were implemented in the real world using the 49E1 railway turnout. The numerical solutions were validated by the experiments. The verification showed a high level of agreement among the results. The obtained results indicate the need for further tests of heating systems, to validate an optimal method of turnout heating. It was found that in the classic ETH, the working space area consumes a tremendous amount of energy. To ensure a higher efficiency of the heating process, the contactless heater is proposed as an alternative.
EN
A highly reflective metal-ceramic anticorrosion coating is proposed to address temperature-induced track arching and concomitant damage of the China Railway Track System II ballastless tracks. The term ceramic refers to the inorganic phosphate coating binder and the metal pertains to the aluminite powder filler. Its thermal properties were studied through finite element modeling and heat radiation testing of uncoated and coated concrete samples and 1:1 ballastless track slab models. The metal–ceramic anticorrosion coating microstructure and constituent characterization were considered in its cooling efficacy analysis. The insulation temperature of the concrete test pieces increased as the thickness of the primer layer increased. At a primer layer thickness of 100 μm, 200 μm, and 300 μm, the corresponding insulation temperature was 8 °C, 18 °C, and 25 °C, respectively. Moreover, the temperature gradient, longitudinal stress, and vertical displacement of a track slab coated with a 300-μm metal-ceramic anticorrosion coating layer decreased by 29%, 57%, and 51.9%, respectively, which agreed well with the simulation results. The reduction in temperature transfer to the substrate, realized by the metal-ceramic anticorrosion coating, holds great promise for application in the construction industry.
EN
The determination of the thermal-elastic behavior is one of the main aspects in the design phase of new machine frames. Prototypically simulation models are used for preliminary investigations, which are based on finite element approaches and usually work with simplified material laws. By the manufacturing of machine frames of concrete steel reinforcements are used to ensure the operation reliability due to the high sensitivity of concrete to tensile stresses. Because of different thermal conductivity and specific heat capacity of steel and concrete the reinforcement has a not negligible influence on the total thermal behavior of the system, which cannot be covered with conventional material laws, e.g. from material libraries. Preliminary investigations show, that a volume fraction more than 1 % of the reinforcement of the total volume can cause a relative error up to ten percent in the temperature field. To reflect the real behavior of reinforced concrete for a machine bed, the influence should be exanimated for two different approaches. Next to the real illustration of the geometry of the reinforcement in the FE-model, decoupled simulation approaches are used on reduced models, which should approach numerically the material behavior of the reinforcement.
EN
The paper consists the problem of developing a scientific toolkit allowing to predict the thermal state of the ingot during its formation in all elements of the casting and rolling complex, between the crystallizer of the continuous casting machine and exit from the furnace. As the toolkit for the decision making task the predictive mathematical model of the ingot temperature field is proposed. Displacement between the various elements of the CRC is accounted for by changing the boundary conditions. Mass-average enthalpy is proposed as a characteristic of ingot cross-section temperature state. The next methods of solving a number of important problems with the use of medium mass enthalpy are developed: determination of the necessary heat capacity of ingots after the continuous casting machine for direct rolling without heating; determination of the rational time of alignment of the temperature field of ingots having sufficient heat capacity for rolling after casting; determination of the total amount of heat (heat capacity) required to supply the metal for heating ingots that have insufficient amount of internal heat.
EN
This work demonstrates the numerical modelling of thermal dispersion accompanying the first stage of the friction stir alloying process. It is very important to recognise the temperature field in the modified workpiece in order to identify the zones where the physical material properties are changing. The temperature gradient leads to a drop of yield strength of the material and, as a consequence, the occurrence of the possibility of plastic flow around the tool. An attempt has been made to analyse the axisymmetric thermal problem described by a Fourier equation with an internal heat source in which the heat is derived only from work of frictional forces occurring between the workpiece and the tool material. The example under consideration focuses on the production of an Al-TiC composite using FSA technology. Macrostructure images of the composite and the simulation results confirm the correctness of the applied mathematical model, where the obtained temperature field corresponds with specific FSA zones.
PL
Praca dotyczy numerycznego modelowania rozkładu temperatury towarzyszącej pierwszej fazie procesu stopowania tarciowego z mieszaniem materiału. Bardzo ważne jest określenie pola temperatury w modyfikowanym materiale w celu identyfikacji obszarów, gdzie właściwości fizyczne materiału ulegają zmianie. Występujący gradient temperatury powoduje obniżenie granicy plastyczności, czego konsekwencją jest umożliwienie plastycznego płynięcia materiału wokół narzędzia mieszającego. Podjęto próbę analizy obrotowo symetrycznego problemu opisanego równaniem typu Fouriera z wewnętrznym źródłem ciepła, gdzie generowane ciepło pochodzi jedynie od pracy sił tarcia występujących pomiędzy materiałem bazowym a materiałem narzędzia. Rozważany problem skupiał się na analizie procesu wytwarzania kompozytu Al-TiC za pomocą technologii FSA . Zdjęcia makrostruktury kompozytu oraz wyniki symulacji numerycznej potwierdzają poprawność zastosowanego modelu matematycznego, a otrzymane pole temperatury nawiązuje do stref właściwych dla procesu FSA.
EN
The current study is a simplification of related components of large floating roof tank and modeling for three dimensional temperature field of large floating roof tank. The heat transfer involves its transfer between the hot fluid in the oil tank, between the hot fluid and the tank wall and between the tank wall and the external environment. The mathematical model of heat transfer and flow of oil in the tank simulates the temperature field of oil in tank. Oil temperature field of large floating roof tank is obtained by numerical simulation, map the curve of central temperature dynamics with time and analyze axial and radial temperature of storage tank. It determines the distribution of low temperature storage tank location based on the thickness of the reservoir temperature. Finally, it compared the calculated results and the field test data; eventually validated the calculated results based on the experimental results.
10
Content available remote Vibration of skew plate with circular variation in thickness and Poisson’s ratio
EN
The present study analyzes the natural vibration of non homogeneous visco elastic skew plate (parallelogram plate) with non uniform thickness under temperature field. Here non homogeneity in the plate's material arises due to circular variation in Poisson's ratio. Also the circular variation in thickness causes non uniformity in the shape of the plate. Bi linear temperature variation on the plate along both the axes is being viewed. The equation of motion related to frequency modes are solved by Rayleigh Ritz method. The findings of the present analysis are presented with the help of tables.
EN
In this work, a model of phase transformations during multipass weld surfaced steel casts is presented. In the temperature field calculation algorithm, the influence of the heat of overlaying beads and a self-cooling of previously overlayed beads have been taken into account. The fusion area, full and part transformation zones, by solidus, A1 and A3 and A A1 temperatures has been determined, respectively. The temperatures of the beginning and the end of the phase changes during cooling were determined on the basis of the time-temperature-transformation welding diagram. In the phase change kinetic description, the JMAK law and KM formula were used. Theoretical considerations are illustrated by example of volume share calculations of particular structural components during the weld surfaced 230-450 W steel cast. The results of computation in the graphical forms are presented: welding thermal cycle diagrams and structural share change histories at selected points, as well as temperature and the phase share distributions in cross section.
EN
The results of a modelling of big size single crystal ZnGeP2 growth dynamics in the multi-zone thermal installation based on the vertical variant of the Bridgman technique are given. Trustworthiness of the results modeling is achieved by means of creation of the mathematical model taking into account the particularities of the installation as well as the changes in installation work volume during crystallization. Temperature field changes during crystal growth by numerical technique were examined. It is demonstrated that growth container moving has a significant impact on temperature field in work volume and crystallization isotherm local position. Thus, the actual crystal growth rate differs from the nominal velocity of growth container moving. The data received as a result of modelling should be taken into account in new equipment designing, crystallization process control system development and crystal growth experiments planning.
EN
The paper presents the analysis of temperature fields, phase transformations, strains and stresses in a cuboidal element made from S235 steel, surfaced with multipass GMA (Gas Metal Arc) method. The temperature field is described assuming a dual-distribution heat source model and summing up the temperature fields induced by the padded weld and by the electric arc. Dependence of stresses on strains is assumed on the basis of tensile curves of particular structures, taking into account the influence of temperature. The calculations were carried out on the example of five welds in the middle of the plate made of S235 steel. The simulation results are illustrated in graphs of thermal cycles, volume shares of structural components and stresses at the selected points of cross-section, and the temperature and strain distributions in the whole cross section.
EN
The paper evaluates two approaches of numerical modelling of solidification of continuously cast steel billets by finite element method, namely by the numerical modelling under the Steady-State Thermal Conditions, and by the numerical modelling with the Traveling Boundary Conditions. In the paper, the 3D drawing of the geometry, the preparation of computational mesh, the definition of boundary conditions and also the definition of thermo-physical properties of materials in relation to the expected results are discussed. The effect of thermo-physical properties on the computation of central porosity in billet is also mentioned. In conclusion, the advantages and disadvantages of two described approaches are listed and the direction of the next research in the prediction of temperature field in continuously cast billets is also outlined.
EN
Induction surface hardening means the hardening of a thin zone of the material only, while its core remains soft. The paper deals with the modelling of the Consecutive Dual Frequency Induction Hardening (CDFIH) of gear wheels and its validation. For gear wheels with modulus m smaller than 6 mm a contour profile of hardness distribution could be obtained. The investigated gear wheel is heated first by a medium frequency inductor to the temperature approximately equal to the modified lower temperature Ac1m. It means beginning of the austenite transformation. Then the gear wheel is heated by the high frequency inductor to the hardening temperature making it possible to complete the austenite transformation and immediately cooled. In order to design the process it is necessary to identify modified critical temperatures and to obtain expected temperature distribution within the whole tooth.
16
Content available remote Modelowanie spawalniczego źródła ciepła w procesie spawania hybrydowego
PL
Bardzo szybki rozwój technik komputerowych umożliwia obecnie analizę naprężeń spawalniczych dla większości procesów spawania. Dość dobrze opisane są rodzaje spawalniczych modeli źródeł ciepła, które są niezbędne dla wyznaczenia pola temperatury podczas spawania. Występujący przy spawaniu gradient temperatury jest jedną z głównych przyczyn powstawania naprężeń spawalniczych, które mogą znacząco wpływać na trwałość eksploatacyjną złączy spawanych. Stąd, modelowanie pola temperatury przy spawaniu jest jednym z niezbędnych elementów służących oszacowaniu odkształceń i naprężeń w konstrukcjach spawanych. Procesy spawania hybrydowego należą do nowej grupy odmian spawania łączących ze sobą najczęściej dwie klasyczne metody spawania jak np. spawanie laserowe i spawanie GMA czy spawanie plazmowe i spawanie GMA. Modelowanie naprężeń spawalniczych w tego typu odmianach spawania wymaga zdefiniowania nowego rodzaju modelu źródła ciepła łączącego skoncentrowany strumień energii z klasycznym źródełem ciepła, jakie występuje w łuku elektrycznym. W pracy przedstawiono próbę opisu modelu spawalniczego źródła ciepła dla spawania hybrydowego w odmianie łuk plazmowy (spawanie plazmowe) + łuk klasyczny (spawanie GMA). W tym celu zbudowano przestrzenny model numeryczny (MES) dwóch płyt stalowych spawanych doczołowo metodą hybrydową (plazma+GMA). Zamieszczono wyniki symulacji numerycznej pola temperatury powstającego przy spawaniu hybrydowym dla zaproponowanego hybrydowego modelu spawalniczego źródła ciepła. Przeprowadzono dyskusję wyników w odniesieniu do kształtu spoiny hybrydowej uzyskanej dla identycznych parametrów procesu spawania hybrydowego.
EN
The rapid development of computer technology now allows for analysis of welding stresses for most welding processes. The types of welding heat sources that are necessary to determine the temperature field during welding are well described. The temperature gradient that occurs during welding is one of the major causes of welding residual stresses that can significantly affect the service life of welded joints. Hence, modeling the temperature field during welding is one of the necessary elements for estimating deformation and stresses in welded constructions. Hybrid welding processes belong to a new group of welding variants that combine most commonly two conventional welding methods, such as laser welding and GMA welding or plasma welding and GMA welding. Modeling of welding residual stresses in this type of welding requires the definition of a new type of heat source model combining a concentrated stream of energy with the classical heat sources present in the welding arc. The paper presents an attempt to describe the model of heat source used in hybrid welding combining the plasma arc (plasma welding) and electric arc (GMA welding). For this purpose, a 3D numerical model (FEM) of two hybrid welded (plasma+GMA) steel plates was used. The results of the numerical simulations of the temperature field generated by hybrid welding for the proposed hybrid heat source model are presented. Discussion of the results with respect to the shape of the hybrid weld obtained for identical parameters of the hybrid welding process was discussed.
17
Content available remote Modele spawalniczych źródeł ciepła w analizie pola temperatury
PL
W pracy przedstawiono charakterystykę podstawowych rodzajów modeli spawalniczych źródeł ciepła wykorzystywanych w analizie pola temperatury. Pierwsza część pracy obejmuje genezę modeli źródeł ciepła przy spawaniu oraz opis takich modeli jak model płaski dyskowy, oraz model podwójnie elipsoidalny Goldaka. W dalszej części pracy przedstawiono przykłady zbudowanych modeli numerycznych spawanych płyt, w których zaimplementowano cztery różne modele źródeł ciepła: dyskowy, podwójnie elipsoidalny, prostopadłościenny i hybrydowy. Zobrazowano wyniki obliczeń numerycznych (MES) w postaci rozkładów pola temperatury w analizowanych modelach oraz dokonano porównania otrzymanych wyników.
EN
The paper presents the characterization of basic types of welding power heat sources used in the analysis of temperature field. The first part of the paper contains the genesis of heat source models used for welding processes. It describes mainly the flat disk and double-ellipsoid Goldak models. The second part of the paper presents as an example numerical (FEM) models of welding heat sources. Four types of disk, double-elispsoid, cuboid and hybrid models were constructed. The results of temperature field obtained from these models were presented and analyzed in comparison to each other. The results of temperature distribution show that it is very important to select adequate type of heat source model for the simulation of a welding process.
PL
W artykule przedstawiono zagadnienia wpływu anomalii i defektów cieplnych na rozkład temperatury ścian zewnętrznych. Błędy wykonawcze powstałe na etapie wznoszenia obiektów budowlanych mogą wpływać na zaburzenie pola temperatury na wewnętrznej i zewnętrznej powierzchni ścian. Zmiany te w większości przypadków są negatywne ze względu na ochronę cieplną budynku. W takich sytuacjach istotne jest dokładne zdiagnozowanie występujących nieprawidłowości, a także poprawne zinterpretowanie powstałych zaburzeń cieplnych. W rozwiązaniu powyższych problemów można wykorzystać dostępne narzędzia obliczeniowe, bazujące m.in. na metodzie elementów skończonych.
EN
This article is dedicated to the study of numerical simulation of temperature field distribution in rolling mill with many cages for continuous casting and rolling stripe of metal wire. In work the simplest is used in use, certainly a steady, economic difference method, a method of division of variables of a multidimensional task into a chain of one-dimensional tasks, a method of total approximation, the locally one-dimensional scheme. The algorithm of numerical modeling of distribution of a temperature field on cages of the rolling mill is constructed. Solutions of the three dimensional temperature field distribution tasks based on experimental data allows finding the temperature across the strip of metal rod in a rolling mill stands. Calculation of the distribution of temperature field in hearth of deformation of a metal rod was realized on implicit scheme. The calculations are shown in the graphs. It provides an analysis of the error of errors.
EN
Aiming at the overheating problem of cable joint, a 3-D finite element model of a single-core cable joint considering the coupling of electromagnetic field and temperature field has been built. In order to consider the heat losses generated by contact resistance of cable joint, the equivalent conductivity is calculated. The validity of the model and calculation method is verified by the comparison with analytical values.
PL
Do analizy zagadnienia przegrzania połączenia kablowego zbudowano trójwymiarowy model MES przy uwzględnieniu sprzężenia pola elektromagnetycznego i temperaturowego. W celu określenia strat ciepła wytwarzanego w rezystancji styku połączenia kablowego obliczono konduktywność zastępczą.
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