Infrared thermography applied to the quantitative determination of spatial and thermophysical parameters of hidden included objects

In this paper we present a study of case of determination of material properties using information from the surface temperature distribution obtained by infrared thermography. Two samples are used for the study: one in gypsum plaster and another with a hidden included steel cylinder. Both samples are heated to 120 °C and their surface temperature distributions are recorded while they are left to be cooled by natural convection in a 30 °C ambient. A simple numerical model is used in order to simulate the transient phenomenon. The parameters are determined by minimizing the deviation between the numerical and experimental results. First the parameters of the gypsum plasterboard are obtained from the information of the plain gypsum plaster sample and after the parameters of the steel inclusion are obtained from the data from the sample with the hidden inclusion. The following parameters are obtained: thermal conductivity and thermal capacity of the gypsum plaster; thermal capacity, radius, position and height of the steel cylinder. During all the presentation we discuss extensively on the particularities of the method when used in this chosen pair of materials. The last section is devoted to summarize the results and discussions.