Application of 3D heat diffusion to detect embedded 3D empty cracks

Abstract

This paper presents a 3D boundary element model (BEM), formulated in the frequency domain, to simulate heat diffusion by conduction in the vicinity of 3D cracks. The model intends to contribute to the interpretation of infrared thermography (IRT) data results and to explore the features of this nondestructive testing technique (NDT) when it is used to detect and characterize defects. The defect is assumed to be a null thickness crack embedded in an unbounded medium. The crack does not allow diffusion of energy, therefore null heat fluxes are prescribed along its boundary. The BEM is written in terms of normal-derivative integral equations (TBEM) in order to handle null thickness defects. The resulting hypersingular integrals are solved analytically.The applicability of the proposed methodology to defect detection tests is studied once the TBEM results have been verified by means of known analytical solutions. Heat diffusion generated by a 3D point heat source placed in the vicinity of a crack is modeled. The resulting thermal waves phase is compared with that obtained when the defect is absent, so as to understand the influence of crack characteristics on the IRT data results analysis, especially on the phase-contrast images. Parameters such as the size of the crack, its shape, its position (buried depth and inclination) and its distance from the heat source are analyzed. Some conclusions are drawn on the effects of varying those parameters.

Evaluation of the state of conservation of mosaics: Simulations and thermographic signal processing

“…The latter step follows the idea studied in Ref. [15], where a model contributed both to the interpretation of IRT results and the exploration of the features of this method when applied for the detection and characterization of sub-superficial defects [73]. However, the 3D defects will not be modeled using a boundary element method (BEM) formulated in frequency domain, as explained in Ref.…”

3D heat diffusion modeling in defected multilayered media for IRT applications in building elements

“…This paper presents an extension to the work developed previously by the authors, where applications using a 3D TBEM formulated in the frequency domain were used to model transient heat transfer by diffusion in unbounded solid media with defects [9], [13] to multilayered media containing 3D thin defects. This paper presents some of the preliminary results, namely the verification of the proposed model.…”

“…The verification of the proposed algorithm was performed using a 3D TBEM formulation for modeling 3D heat diffusion in the vicinity of a 3D thin inclusion [9] embedded in an unbounded medium which has been previously validated against known analytical solutions. 10.21611/qirt.2016.162…”

“…Total heat field is found by adding the heat source terms equal to those in an unbounded space with the surface terms generated at each interface in order to ensure the continuity of temperature and heat flux at each interface. The proposed formulation is verified using a previously 3D TBEM model [9] used to simulate the heat diffusion in the presence of thin defects embedded in an unbounded medium.…”

3D heat diffusion simulation using 3D and 1D heat sources – Temperature and phase contrast results for defect detection using IRT

“…In the present study, the BEM is used to model 3D heat diffusion in a homogeneous unbounded solid medium. The benefits and disadvantages of using the BEM in this type of problem are explored in the authors' previous studies [16]. One of the major difficulties stems from the null thickness of the defect being modeled.…”