Approaches for coupled numerical simulation of high frequency tube welding process

Welding processes and installations used nowadays are mainly developed on practical experience and analytical calculations. Nevertheless, high frequency induction tube welding is a very complex three-dimensional dynamic process, where the electromagnetic and thermal characteristics are distributed not only in space but in time as well. A more profound detailed investigation of the induction tube welding process can be only done by numerical modelling. Full and local three-dimensional transient numerical models of induction tube welding process with continuous movement of the welded tube have been developed and tested. Coupled electromagnetic and thermal analyses are carried out at each time step of simulation for correction of temperature dependent material properties. Voltage or current of the induction coil can be individually input into electromagnetic analysis at each time step. This approach allows simulating “quasi” steady-state and transient operation modes

Coupled numerical multiphysics simulation methods in induction surface hardening

Numerical simulation is a valuable tool to help investigate complex multiphysics problems of engineering and science. This also applies to inductive surface hardening with its coupled electromagnetic and temperature fields as well as the microstructure changes of the hardened material. In this field, numerical simulation is a well-established approach for effective process design. This is particularly true since an analytical approach usually fails because of the complexity of the problems. Also, experiments oftentimes are not leading to a solution in an acceptable period of time because of the big number of process parameters. Furthermore, numerical simulation can help to investigate effects that could not have been observed otherwise. An example is the Joule heat distribution within a heated work piece during inductive heating. However, the fields of application as well as the methods of numerical simulation have to keep pace with technological progress. Two examples of new applications and methods for numerical simulation in induction hardening are presented in this paper: A complex 3D model of a large bearing and a new approach for the numerical simulation of the martensite microstructure

FERROELECTRIC NANOCOMPOSITES WITH GOVERNED INTERFACE ON BASE OF MAGNETIC POROUS GLASSES

Two-phase (nonporous) magnetic alkali borosilicate glasses have been produced by induction melting. Their macroscopic properties and crystal structure have been studied and it is shown that in the silica skeleton there are the agglomerates of Fe3O4. These agglomerates are formed by monodomain nanoparticles of magnetite and demonstrate the superparamagnetic properties. After special thermal treatment (liquation process) and chemical etching the nanoporous matrices with random dendrite pore structure and magnetic properties have been produced. The channels (porous space) were filled by ferroelectric materials KH2PO4 (KDP), KH2PO4+(NH4)H2PO4 (KDP-ADP or KADP), and NaNO2 and the effect of applied magnetic fields on phase transitions in these nanocomposite have been studied. It has also been established that a restricted geometry changed essentially the phase diagram of KADP.

Numerical simulation and investigation of induction through-heaters in dynamic operation mode

Purpose - Because of their widespread use in industry, induction through-heaters of various metal products must be of high effectiveness not only in "quasi" steady-state operation but in different transient modes as well. Nowadays, they are usually designed to provide the required characteristics in "quasi" steady-state operation mode mainly. The purpose of this paper is to examine numerical simulation of transient processes in induction through-heating lines generally and investigate dynamic temperature fields during the first start of the heaters particularly. Design/methodology/ approach - The research methodology is based on coupled numerical electromagnetic and thermal analyses using FEM approach. ANSYS simulations are supported with the developed tools for imitation of mass transfer effects in continuous induction heating lines. Findings - The results show that transient temperature fields in the heated strip or slab significantly differ from their "quasi" steady-state descriptions. Local temperature variations acquired in longitudinal as well as transverse flux induction heaters during the first start have been predicted. Practical implications - The received results can be used for design of induction through-heaters and improvement of their characteristics in dynamic operation modes. Originality/value - Investigation of dynamic characteristics of the heaters in dynamic modes can be only done by numerical modelling based on special algorithms providing a time loop additional to coupling between electromagnetic and thermal analyses. Such algorithms have been developed and used for investigation of two types of induction installations: through-heaters of cylindrical billets for forging and heating lines of strip or thin slab for rolling mills. © 2011 Emerald Group Publishing Limited. All rights reserved

Approaches for coupled numerical simulation of high frequency tube welding process

Welding processes and installations used nowadays are mainly developed on practical experience and analytical calculations. Nevertheless, high frequency induction tube welding is a very complex three-dimensional dynamic process, where the electromagnetic and thermal characteristics are distributed not only in space but in time as well. A more profound detailed investigation of the induction tube welding process can be only done by numerical modelling. Full and local three-dimensional transient numerical models of induction tube welding process with continuous movement of the welded tube have been developed and tested. Coupled electromagnetic and thermal analyses are carried out at each time step of simulation for correction of temperature dependent material properties. Voltage or current of the induction coil can be individually input into electromagnetic analysis at each time step. This approach allows simulating “quasi” steady-state and transient operation modes

Coupled numerical multiphysics simulation methods in induction surface hardening

Numerical simulation is a valuable tool to help investigate complex multiphysics problems of engineering and science. This also applies to inductive surface hardening with its coupled electromagnetic and temperature fields as well as the microstructure changes of the hardened material. In this field, numerical simulation is a well-established approach for effective process design. This is particularly true since an analytical approach usually fails because of the complexity of the problems. Also, experiments oftentimes are not leading to a solution in an acceptable period of time because of the big number of process parameters. Furthermore, numerical simulation can help to investigate effects that could not have been observed otherwise. An example is the Joule heat distribution within a heated work piece during inductive heating. However, the fields of application as well as the methods of numerical simulation have to keep pace with technological progress. Two examples of new applications and methods for numerical simulation in induction hardening are presented in this paper: A complex 3D model of a large bearing and a new approach for the numerical simulation of the martensite microstructure