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

Abstract

Highlights A boundary element method (BEM) formulated in the frequency domain is used to simulate 3D heat diffusion around a 3D null thickness crack; The boundary element method (BEM) is formulated in terms of normal-derivative integral equations (TBEM); A formulation is presented for calculating the heat field generated by a 1D and 3D heat sources; Temperature and phase-contrast images are computed for defect detection using infrared thermography (IRT); The influence of the geometry of the source is studied for varying crack size, shape, position. AbstractInfrared thermography (IRT) has proven to be a powerful non-destructive technique and it has been successfully used for detecting defects in a wide range of applications and sectors. Numerical modeling of heat transfer and diffusion in the presence of defects combined with experimental IRT results may be used both to detect and characterize existing defects with specific geometries and depths. However, the three-dimensional (3D) nature of defects combined with the need to simulate heat transfer and diffusion phenomena in transient regime often presents many challenges for researchers. The study presented in this paper is motivated by such difficulties and is intended to contribute to the interpretation of quantitative data results collected in experimental defect detection IRT tests and help with the definition of IRT experimental set-up parameters.In this study, 3D heat diffusion by conduction in the proximity of a 3D defect is modelled using a boundary element method (BEM) formulated in the frequency domain. The defect is a crack lodged in an unbounded solid medium with null thickness. In order to overcome difficulties that occur in the presence of null thickness elements, the BEM formulation was written in terms of normal-derivative integral equations (TBEM) and known analytical solutions were used to solve the resulting hypersingular integrals. The focus of this paper is to study the influence that using either a 3D (point) energy source or a 1D (planar) energy source in heat diffusion simulations performed for IRT defect detection studies. Heat field and thermal wave phase results were computed in the presence of a defect and for when there is no defect present and a comparative analysis of the results obtained for a point and a planar source was carried out. So has to contribute to defects characterization studies, the influence of the crack's characteristics such as its size, shape and placement (depth and position) was analyzed using a phase contrast approach. Other features that may be relevant in IRT experiments, such as the nature of the stimulus provided and its distance from the surface were also studied. The major findings achieved from varying those parameters are presented in the conclusions.

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

“…However, the 3D defects will not be modeled using a boundary element method (BEM) formulated in frequency domain, as explained in Ref. [16], although one of the most advanced techniques, i.e., the partial least-square thermography (PLST) [74] along with others if needed, will be applied to the numerical simulations with the aim to detect a great number of fabricated defects.…”

Microstructure and Thermal Reliability of Microcapsules Containing Phase Change Material with Self-Assembled Graphene/Organic Nano-Hybrid Shells

“…IRT has been widely applied to measure the radiant thermal energy distribution and heat conduction behavior emitting from a target. For example, this technology is employed to complete the non-destructive evaluation or non-destructive devaluation applied to composite structures [ 27 ]. Furthermore, IRT is particularly useful to detect the material structure at micro-scale level.…”

“…The reason is that the MMF polymer usually possesses an e value between 0.90 and 0.98 [ 30 ]. Because IRT is only a technology to inspect solid structures and is also considered a ‘boundary technique’, this means its ability for inspection is limited to a certain depth of the target to subsurface defect detection [ 27 ]. Therefore, the microPCM particles were piled together with the same area and height avoiding the influence of the sample’s shape.…”

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.…”