Inverse technique for determining temperature dependence of material properties

Abstract

Purpose This paper aims to present a methodology of finding temperature dependencies of selected physical parameters of metals. The method is based on the combination of measurement of the surface temperature of material during the process of heating and subsequent solution of the inverse problem using multi-parametric optimization. Design/methodology/approach The methodology is based on measurements and numerical solution of the forward and inverse problem, taking into account all involved nonlinearities (saturation curve of the processed steel material and temperature dependences of its physical parameters). The inverse problem is solved by a genetic algorithm. Findings The suggested methodology was successfully verified on several metal materials whose temperature-dependent parameters are known. The calculated and measured results exhibit a very good accordance (the differences do not exceed about 10 per cent for room and higher temperatures). Research limitations/implications At this moment, the methodology successfully works when the temperature dependence of just one material parameter is to be found (which means that the temperature dependencies of other parameters are known). The accuracy of results also depends on the correctness of other input data. Practical implications This paper provides a relatively easy possibility of finding the temperature dependencies of thermal conductivity or heat capacity of various alloys. Originality/value The paper proposes a methodology of finding the temperature dependence of a given material parameter that is not known in advance (which is of great importance in case of alloys).

An Inductive Method for Comprehensive Estimation of Temperature-Dependent Electrical and Thermal Properties of Conductive Ferromagnetic Materials

“…Therefore, it seems reasonable to develop a method allowing for as accurate as possible estimation of these characteristics, preferably on one research stand. Attempts [2][3][4][5][6][7][8][9] to simultaneously determine more than one parameter are usually based on the use of optimization techniques, but especially with a wide range of permissible changes in parameter values, they are burdened with a high risk of error. The solution can be sought [10,11] in the measurement estimation of parameters at one stand, which then, depending on the obtained and required accuracy, can be treated as final results or as an introduction to the optimization process of simultaneous determination of characteristics but with a strongly narrowed range of permissible changes decision variables (parameter values).…”

“…On the other hand, growing technological requirements increasingly lead to the need for precise, reliable information about the properties of the processed material, which leads to the need to verify them in situ. The importance of the problem raised is confirmed by numerous publications [2][3][4][5][6][7][8][9][10][11], in which the issue of the possibly simplest and quickest way to determine material properties is considered, preferably several at once using one measurement station. The cited literature examples mainly concern attempts to determine thermal properties, that is, thermal diffusivity and volumetric heat capacity.…”

“…The above-mentioned methods for simultaneous determination of more than one thermal material property are based on solving the problem of reverse heat conduction. A similar approach to determining the thermal material properties of metals, but using the induction heating method, is presented in the studies [8,9]. Also here, based on optimization techniques and measurement of temperature distribution in the tested sample, the possibility of indirectly determining the thermal properties of materials was indicated.…”

“…This extension involves performing measurement experiments on a test stand that will enable, with the highest possible accuracy, the estimation of the value of each of the sought material parameters separately. This allows for a very significant reduction in the range of variability of these parameters, the exact value of which can then be determined in the procedure of solving the inverse heat conduction problem (for example, in [8,9]), where a comprehensive multi-factor analysis is performed. A full development of this approach using the induction method as a source of excitation was presented for conductive, non-magnetic materials in [11].…”

Method of Determining the Temperature Characteristics of the Thermal and Electrical Properties of Conductive Materials on a Stand for Induction Heating

“…These methods, however, are still based on the use of a contact, i.e., a resistive heat source, which makes them less useful, especially in the case of the higher temperatures usually encountered in the thermal processes of metalworking. A similar approach to determining the thermal material properties of metals, but using the non-contact method of energy transfer (the phenomenon of magnetic induction on the induction heating station) is presented in [7,8]. Additionally, based on optimization techniques of solving the inverse problem and measuring the temperature distribution during induction heating, the possibility of indirectly determining the thermal properties of materials was also indicated.…”