Nondestructive evaluation of the thermophysics properties materials by IR thermography

The aim of this paper is improving, development and application of pulsed thermography as experimental method for detection of defect in material. To accomplish this, the paper has 3 aspects: 1. Experimental research including оf development and improving conditions for measuring and data acquisition. 2. Theoretical research containing of analytical and numerical solving the system of partial differential equations for heat convection by conduction, with corresponding initial and boundary conditions. 3. Theoretical research considering method and procedure application in pulsed infrared thermography for given theoretical and experimental conditions. During the first part of research, specific samples were prepared for experiment where at one side of the plate equally spaced slots are forming the periodical structure of defects with defined spatial frequency and depth. The other side of plate was irradiated with short light pulse and temperature distribution on that side was analyzed by pulsed infrared thermography. The second part of the research, considers different models describing twodimensional heat conduction through planparallel plate with defect in form of flat-bottom slot, with general and specific initial and boundary conditions. In the third part of research, comparison of experimental results and results of simulation was made to determine the conditions and limits of method applicability for periodically structured defects. The theoretical analysis and experimental testing of the method was done for the defects in aluminum plate. Cilj ovog rada je poboljšanje, razvoj i primena impulsne termografije kao eksperimentalnog metoda za otkrivanje defekata u materijalu. Da bi se ostvario taj zadatak, rad je usmeren ka tri sledeća pravca: 1. Eksperimentalna istraživanja koja obuhvataju razvoj i poboljšanja uslova za merenje i akviziciju podataka. 2. Teorijska istraživanja koja obuhvataju analitičko i numeričko rešavanje sistema parcijalnih diferencijalnih jednačina provođenja toplote kondukcijom uz odgovarajuće početne i granične uslove. 3. Teorijska istraživanja koja podrazumevaju primenu metode i procedure u impulsnoj infracrvenoj termografiji za date teorijske i eksperimentalne uslove. U toku prvog dela istraživanja, izrađeni su posebni uzorci pripremljeni za eksperiment, gde su na jednoj strani ploče podjednako razmaknuti žljebovi praveći periodičnu defektnu strukturu sa određenom prostornom frekfencijom i određenom dubinom. Druga strana ploče bila