Characterization and spatial resolution of cracks using lock-in vibrothermography

Mendioroz, A.; Castelo, A.; Celorrio, R.; Salazar, A.

doi:10.1016/j.ndteint.2014.04.004

Cited by 23 publications

(31 citation statements)

References 20 publications

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“…1D Ω = θ (5) where each point of the matrix A is calculated with Equation (4) [11]. The choice of the thickness discretization requires some remarks:…”

Section: Direct Problemmentioning

confidence: 99%

“…As an example, let us consider a problem of 3 point sources p 1 (5,3,27), p 2 (11,11,11) and p 3 (18,17,20) placed in a volume discretized in n x = 20, n y = 20, and n z = 30, as illustrated in Figure 6. Figure 7a represents the 400 measured temperature as function of time, which constitutes the time evolution of the surface temperature T sur f (x, y, t).…”

Section: Generalization Of the Bayesian Approach To 3d Source Reconstmentioning

confidence: 99%

“…Among the different methods used to tackle heat source reconstruction, the work of Castelo et al [3][4][5][6][7][8] proposes detecting defects present in a vertical plane on the surface of the material by exciting them with modulated (lock-in) or pulsed (burst) acoustic waves, creating a thermal source at the spot of the defect; the characterization of the defect takes place by the characterization of the resulting thermal source. This reconstruction uses an original regularization term.…”

Section: Introductionmentioning

confidence: 99%

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Bayesian Inference for 3D Volumetric Heat Sources Reconstruction from Surfacic IR Imaging

et al. 2020

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The domain of non-destructive testing (NDT) or thermal characterization is currently often done by using contactless methods based on the use of an IR camera to monitor the transient temperature response of a system or sample warmed by using any heat source. Though many techniques use optical excitation (flash lamps, lasers, etc.), some techniques use volumetric sources such as acoustic or induction waves. In this paper, we propose a new inverse processing method, which allows for the estimation of 3D fields of heat sources from surface temperature measurements. This method should be associated with volumetric heat source generation. To validate the method, a volumetric source was generated by the Joule effect in a homogeneous PVC sample using an electrical thin cylindrical wire molded in the material. The inverse processing allows us to retrieve the depth of the wire and its geometrical shape and size. This tool could be a new procedure for retrieving 3D defects on NDT.

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“…1D Ω = θ (5) where each point of the matrix A is calculated with Equation (4) [11]. The choice of the thickness discretization requires some remarks:…”

Section: Direct Problemmentioning

confidence: 99%

Section: Generalization Of the Bayesian Approach To 3d Source Reconstmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Bayesian Inference for 3D Volumetric Heat Sources Reconstruction from Surfacic IR Imaging

et al. 2020

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“…Then, the study has been extended on 3D problems; several pioneering teams have proposed methods based on thermal and acoustic coupling [2][3][4][5][6] or by introducing the concept of virtual waves [7,8]. These methods of reconstruction that exist today enable reconstructing volume data (sources, initial conditions, etc.)…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Reconstruction of Thermal Volumetric Sources from Surface Temperature Fields Measured by Infrared Thermography

et al. 2019

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Non-destructive testing (NDT) of materials and structures is a very important industrial issue in the fields of transport, aeronautics and space as well as in the medical domain. Active infrared thermography is an NDT method that consists of providing an external excitation to cause an elevation of the temperature field in the material, consequently allowing evaluation of the resulting temperature field at the surface. However, thermal exciters that are used (flash lamps, halogen, lasers) act only on the surface of the sample. On the other hand, several energy conversion systems can lead to the generation of volumetric sources; the phenomena of thermo-acoustics, thermo-induction, thermomechanics or thermochemistry can be cited. For instance, ultrasonic waves can generate volumetric heat sources if the material is viscoelastic or if there is a defect. The reconstruction of these sources is the initial process for the quantification of parameters responsible for the heating. Characterizing a heat source means reconstructing its geometry and the supplied power. Identification of volumetric heat sources from surface temperature fields is a mathematically ill-posed problem. The main cause of the issue is the diffusive nature of the temperature. In this work, 3D reconstruction of the volumetric heat sources from the resulting surface temperature field, measured by infrared thermography, is studied. An analysis of the physical problem enables specifying the limits of the reconstruction. In particular, a criterion on the achievable spatial resolution is defined, and a reconstruction limitation for in-depth sources is highlighted.

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“…The most extended modality of thermography used to evaluate materials is the one denominated as active thermography, which is based on the study of the thermal reaction of the material when external signal stimulation is applied. The signal can be applied in different ways, such as heat pulses [15], one-frequency modulated signal, also known as lock-in method [16], mechanical vibrations [17], ultrasounds [18], and microwaves [19]. In this paper, authors apply a new approach to establish a protocol for the prediction of crack depth from cooling rate data.…”

Section: Introductionmentioning

confidence: 99%

Crack-Depth Prediction in Steel Based on Cooling Rate

Rodríguez‐Martín¹,

Lagüela

González‐Aguilera³

et al. 2016

Advances in Materials Science and Engineering

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One criterion for the evaluation of surface cracks in steel welds is to analyze the depth of the crack, because it is an effective indicator of its potential risk. This paper proposes a new methodology to obtain an accurate crack-depth prediction model based on the combination of infrared thermography and the 3D reconstruction procedure. In order to do this, a study of the cooling rate of the steel is implemented through active infrared thermography, allowing the study of the differential thermal behavior of the steel in the fissured zone with respect to the nonfissured zone. These cooling rate data are correlated with the real geometry of the crack, which is obtained with the 3D reconstruction of the welds through a macrophotogrammetric procedure. In this way, it is possible to analyze the correlation between cooling rate and depth through the different zones of the crack. The results of the study allow the establishment of an accurate predictive depth model which enables the study of the depth of the crack using only the cooling rate data. In this way, the remote measure of the depth of the surface steel crack based on thermography is possible.

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Characterization and spatial resolution of cracks using lock-in vibrothermography

Cited by 23 publications

References 20 publications

Bayesian Inference for 3D Volumetric Heat Sources Reconstruction from Surfacic IR Imaging

Bayesian Inference for 3D Volumetric Heat Sources Reconstruction from Surfacic IR Imaging

Three-Dimensional Reconstruction of Thermal Volumetric Sources from Surface Temperature Fields Measured by Infrared Thermography

Crack-Depth Prediction in Steel Based on Cooling Rate

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