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Andreas Mandelis - One of the best experts on this subject based on the ideXlab platform.
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quantitative lock in thermography imaging of Thermal Wave spatial profiles and thermophysical property measurements in solids with inner corner geometries using Thermal Wave field theory
Journal of Applied Physics, 2018Co-Authors: Andreas Mandelis, Mingfeng Wang, Alexander Melnikov, Chinhua WangAbstract:In this study, we established a theoretical photoThermal model and its experimental validation for an infinitely long solid with an inner corner of arbitrary opening angle, with the solid being irradiated photoThermally by a modulated laser beam of arbitrary spatial intensity distribution directed to the corner. The Thermal-Wave field distribution on the flat surfaces of the solid centered at the corner was obtained using the Green function method. Experimental results based on quantitative thermographic imaging were obtained and used to validate the theoretical model in which Thermal diffusivity of an inner cornered stainless steel was measured. The Thermal-Wave theory based lock-in thermography imaging technique provides a quantitative tool for Thermal property measurement and/or non-destructive evaluation of non-flat structures. It also generates valuable physical insights into the spatial distribution of the Thermal-Wave field in the neighborhood of geometric discontinuities such as inner corners in solids.
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modeling of Thermal Wave fields in radially inhomogeneous spherical solids using the green function method
International Journal of Thermophysics, 2012Co-Authors: Jie Zhang, Guangxi Xie, Chinhua Wang, Andreas MandelisAbstract:A theoretical model for evaluating solid multilayered spherical solids heated by a frequency-modulated light beam using the Green function method is presented. The specific Thermal-Wave Green function corresponding to the composite structure has been derived. The characteristics of the Thermal-Wave field with respect to the thermophysical, geometrical, and measurement parameters are presented. Unlike the quadrupole method, the Green function method is capable of evaluating Thermal-Wave fields at any point of multilayered structures with arbitrary intensity distributions of the incident laser beams. This study establishes applications of Thermal-Wave fields in both cylindrical and spherical samples using the Green function method and is of importance in characterizing radially inhomogeneous spherical solids.
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Thermal conductivity depth profile reconstruction of multilayered cylindrical solids using the Thermal Wave green function method
Journal of Applied Physics, 2011Co-Authors: Guangxi Xie, Chinhua Wang, Jie Zhang, Liwang Liu, Andreas MandelisAbstract:In this paper, a theoretical model for characterizing solid multi-layered cylindrical samples illuminated by a modulated uniform incident beam is developed by means of the Green function method. The specific Green function for the multi-layered cylindrical structure is derived and an analytical expression for the Thermal-Wave field in such a cylindrical sample is presented. The Thermal-Wave field of an inhomogeneous cylindrical sample irradiated with incident light of arbitrary angular and/or radial intensity distribution was obtained using this theoretical model. Furthermore, experimental validation is also presented in the form of experimental results with steel cylinders of various diameters.
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thermophotonic radar imaging an emissivity normalized modality with advantages over phase lock in thermography
Applied Physics Letters, 2011Co-Authors: Nima Tabatabaei, Andreas Mandelis, Bennett T AmaechiAbstract:One major problem of frequency-domain photoThermal radiometry, or alternatively in two-dimensional lock-in thermography, is the compromise one has to make between dynamic range (probing depth) and depth resolution. The Thermal-Wave radar incorporates chirped excitation through matched filtering to maintain good resolution and depth range inside a sample. This letter experimentally demonstrates the advantages of chirped modulation and introduces a thermophotonic modality of Thermal-Wave radar based on an emissivity-normalized, higher-dynamic-range contrast parameter known as cross-correlation phase. Finally, comparisons made on a biological (dental) sample show potential applications of the method.
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reconstruction of radial Thermal conductivity depth profile in case hardened steel rods
Journal of Applied Physics, 2009Co-Authors: R Celorrio, A Mendioroz, E Apinaniz, A Salazar, Chinhua Wang, Andreas MandelisAbstract:In this work the surface Thermal-Wave field (ac temperature) of a solid cylinder illuminated by a modulated light beam is calculated first in two cases: a multilayered cylinder and a cylinder the radial Thermal conductivity of which varies continuously. It is demonstrated numerically that, using a few layers of different thicknesses, the surface Thermal-Wave field of a cylindrical sample with continuously varying radial Thermal conductivity can be calculated with high accuracy. Next, an inverse procedure based on the multilayered model is used to reconstruct the radial Thermal conductivity profile of hardened C1018 steel rods, the surface temperature of which was measured by photoThermal radiometry. The reconstructed Thermal conductivity depth profile has a similar shape to those found for flat samples of this material and shows a qualitative anticorrelation with the hardness depth profile.
Ravibabu Mulaveesala - One of the best experts on this subject based on the ideXlab platform.
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Novel Analytical Approach for Estimation of Thermal Diffusivity and Effusivity for Detection of Osteoporosis
IEEE Sensors Journal, 2020Co-Authors: Anshul Sharma, Ravibabu Mulaveesala, Vanita AroraAbstract:Infrared thermography is a full field, non-contact inexpensive, patient friendly and safe imaging modality for estimation of thermo-physical properties of various bio-materials. Among the widely used Thermal Wave imaging modalities, recently proposed frequency modulated Thermal Wave imaging technique gained importance due to its quantitative characterization capabilities along with its deeper subsurface visualization abilities. This work highlights a novel analytical analysis for three dimensional Fourier heat diffusion equation by considering internal heat generation. An aperiodic pulse compression favorable Thermal Wave imaging method is proposed for estimation of thermo-physical properties of bone for identification of severity of osteoporosis. Effect of osteoporosis on thermo-physical properties such as Thermal effusivity and diffusivity has been studied. Further proposed analytical approach has been validated by results obtained from the commercially available finite element based COMSOL software.
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an independent component analysis based approach for frequency modulated Thermal Wave imaging for subsurface defect detection in steel sample
Infrared Physics & Technology, 2019Co-Authors: Ravibabu Mulaveesala, Javed Ahmad, Aparna Akula, Harish Kumar SardanaAbstract:Abstract Infrared thermography (IRT) is extensively used as non-destructive testing and evaluation (NDT&E) technique to inspect and characterize various solid materials and structures. In this paper, an emergent optical thermography NDT&E technique i.e. frequency modulated Thermal Wave imaging (FMTWI) has been used for the inspection of mild steel sample embedded with artificially constructed flat bottom circular holes of the same diameter at various depth. This article proposes an independent component analysis (ICA) to process the FMTWI image sequence for detecting the subsurface defects of mild steel sample. To evaluate the effectiveness of defect detection capability of the proposed method, the conventional data processing techniques viz. phase analysis, pulse compression and principal component analysis (PCA) have been compared with ICA. The signal-to-noise (SNR) has been considered to characterize and quantify the defect detectability and compared with conventional post-processing techniques to validate the efficiency of the proposed approach. The obtained results provide an insight into the robustness of the ICA approach for defect detection. Furthermore, an active contour model-based object detection technique has been employed for identification, localization, and extraction of the shape of the defects.
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pulse compression approach to nonstationary infrared Thermal Wave imaging for nondestructive testing of carbon fiber reinforced polymers
IEEE Sensors Journal, 2015Co-Authors: Vanita Arora, Ravibabu Mulaveesala, Juned A Siddiqui, Amarnath MuniyappaAbstract:Infrared thermography (IRT) is one of the promising remote and whole field inspection techniques for nondestructive characterization of various solids. This technique relies on the mapping of surface temperature response to detect the presence of surface and subsurface anomalies within the material. Due to its fast and quantitative testing capabilities, the IRT has gained significant importance in the testing of fiber reinforced polymers (FRP). A carbon FRP sample with flat bottom holes is considered for inspection using nonstationary digitized frequency modulated Thermal Wave imaging technique. Furthermore, depth scanning performance using frequency domain-based phase approach has been compared with recently proposed time domain phase approach.
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pulse compression with gaussian weighted chirp modulated excitation for infrared Thermal Wave imaging
Progress in Electromagnetics Research Letters, 2014Co-Authors: Vanita Arora, Ravibabu MulaveesalaAbstract:This paper proposes a novel signal processing approach to Thermal non-destructive testing by incorporating Gaussian window function onto the linear frequency modulated incident heat ∞ux to achieve better pulse compression properties. The present work highlights a flnite element analysis based modeling and simulation technique in order to test the capabilities of the proposed windowing scheme over the conventional frequency modulated Thermal Wave imaging method. It is shown that by using Gaussian weighted chirp Thermal stimulus, high depth resolution can be achieved.
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quadratic frequency modulated Thermal Wave imaging for non destructive testing
Progress in Electromagnetics Research M, 2012Co-Authors: Ghali Venkata Subbarao, Ravibabu MulaveesalaAbstract:Thermal non-destructive testing and evaluation of glass flbre reinforced plastic materials has gained more importance in aerospace industry due to low weight and high strength capabilities in severe environmental conditions. More recently, pulse compression favorable non-stationary excitation schemes have been exhibiting reliable defect detection capabilities in infrared non-destructive testing. This paper introduces a novel infrared non-destructive testing method based on quadratic frequency modulated Thermal Wave imaging with pulse compression for characterization of glass flbre reinforced plastic materials. Defect detection capability of the proposed method has been experimentally validated using a glass flber reinforced plastic (GFRP) sample with embedded Te∞on inserts. Experimental results proved the enhanced depth resolution capability of the proposed excitation method as compared to the linear frequency modulation with pulse compression.
Suneet Tuli - One of the best experts on this subject based on the ideXlab platform.
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Applicability of LED-Based Excitation Source for Defect Depth Resolved Frequency Modulated Thermal Wave Imaging
IEEE Transactions on Instrumentation and Measurement, 2017Co-Authors: Suneet TuliAbstract:This paper proposes an energy efficient instrumentation set-up for pulse-compression Thermal-Wave imaging with a low-power LED excitation source. The set-up consists of three different subsystems that are synchronised in time. The individual systems consist of a LED modulation circuitry, reference signal measurement circuitry, and an IR camera trigger signal generation circuitry for frame capture. A separate reference acquisition circuitry is useful in quantifying defect depth resolution. This paper also proposes a nonuniform frame capture technique to reduce the memory allocation space of the recorded video. The technique is based on varying the sampling rate with a change in instantaneous frequency and is specifically useful for frequency modulated excitation signal. The proposed technique is implemented on a carbon fiber reinforced polymer test-piece. The variation of pulse compression parameters with different defect dimension is studied, and the results are verified with an electro-Thermal simulator. Further, an objective comparison of pulse compression experiment for different experiment duration is presented.
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theory of frequency modulated Thermal Wave imaging for nondestructive subsurface defect detection
Applied Physics Letters, 2006Co-Authors: Ravibabu Mulaveesala, Suneet TuliAbstract:This letter provides the theory and mathematical analysis in support of a recently proposed frequency modulated Thermal Wave imaging for nondestructive subsurface defect detection in solids. The authors illustrate how the technique simultaneously combines the advantages of both conventional pulse based thermography as well as modulated lock-in thermography. A specimen is heated for launching Thermal Waves into the sample, not at a single frequency (lock-in) or at all frequencies (pulse), but in a desired range of frequencies. While peak power requirement is reduced, phase images obtained retain known advantages. Experimental results from a carbon fiber reinforced plastic sample are presented in support.
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interface study of bonded wafers by digitized linear frequency modulated Thermal Wave imaging
Sensors and Actuators A-physical, 2006Co-Authors: Ravibabu Mulaveesala, Suneet TuliAbstract:Thermography is a whole field, non-contact and non-destructive characterization technique that is widely used for the investigation of sub-surface features in various kinds of solid materials (conductors, semiconductors, insulators and polymers). In this work, a new method is proposed and demonstrated for the interface study of the bonded wafers that are frequently used in MEMS and VLSI. For the demonstration, two oxidized wafers are direct bonded: one plane and the other having anisotropically etched cavities. To observe the effect of annealing on bonding, the bonded pair was annealed at different temperatures for a fixed period, and also for different time periods at a fixed temperature. Compared to conventional passive Wave and pulse thermography techniques, the proposed digitized linear frequency modulated Thermal Wave imaging (DFMTWI) method overcomes certain drawbacks associated with conventional Thermal imaging techniques: in comparison to lock-in thermography it requires very less experimentation time whereas in comparison with pulse thermography less peak power heat sources are sufficient. It is further demonstrated that DFMTWI, in principle, is capable of differentiating depths of various cavities, and the Thermal phase images can lead to actual depth estimation also.
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defect detection by pulse compression in frequency modulated Thermal Wave imaging
Quantitative InfraRed Thermography, 2005Co-Authors: Suneet Tuli, Ravibabu MulaveesalaAbstract:A new, quantitative, whole field, non-contact and non-destructive technique for sub-surface defect detection is presented based on frequency modulated Thermal Wave imaging (FMTWI). Electro-Thermal modeling and MATLAB-SIMULINK simulation has been carried out for the proposed technique. Experimental results of frequency modulated Thermal Wave imaging are reported, and defect detection by a correlation approach demonstrated.
Chinhua Wang - One of the best experts on this subject based on the ideXlab platform.
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quantitative lock in thermography imaging of Thermal Wave spatial profiles and thermophysical property measurements in solids with inner corner geometries using Thermal Wave field theory
Journal of Applied Physics, 2018Co-Authors: Andreas Mandelis, Mingfeng Wang, Alexander Melnikov, Chinhua WangAbstract:In this study, we established a theoretical photoThermal model and its experimental validation for an infinitely long solid with an inner corner of arbitrary opening angle, with the solid being irradiated photoThermally by a modulated laser beam of arbitrary spatial intensity distribution directed to the corner. The Thermal-Wave field distribution on the flat surfaces of the solid centered at the corner was obtained using the Green function method. Experimental results based on quantitative thermographic imaging were obtained and used to validate the theoretical model in which Thermal diffusivity of an inner cornered stainless steel was measured. The Thermal-Wave theory based lock-in thermography imaging technique provides a quantitative tool for Thermal property measurement and/or non-destructive evaluation of non-flat structures. It also generates valuable physical insights into the spatial distribution of the Thermal-Wave field in the neighborhood of geometric discontinuities such as inner corners in solids.
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modeling of Thermal Wave fields in radially inhomogeneous spherical solids using the green function method
International Journal of Thermophysics, 2012Co-Authors: Jie Zhang, Guangxi Xie, Chinhua Wang, Andreas MandelisAbstract:A theoretical model for evaluating solid multilayered spherical solids heated by a frequency-modulated light beam using the Green function method is presented. The specific Thermal-Wave Green function corresponding to the composite structure has been derived. The characteristics of the Thermal-Wave field with respect to the thermophysical, geometrical, and measurement parameters are presented. Unlike the quadrupole method, the Green function method is capable of evaluating Thermal-Wave fields at any point of multilayered structures with arbitrary intensity distributions of the incident laser beams. This study establishes applications of Thermal-Wave fields in both cylindrical and spherical samples using the Green function method and is of importance in characterizing radially inhomogeneous spherical solids.
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Thermal conductivity depth profile reconstruction of multilayered cylindrical solids using the Thermal Wave green function method
Journal of Applied Physics, 2011Co-Authors: Guangxi Xie, Chinhua Wang, Jie Zhang, Liwang Liu, Andreas MandelisAbstract:In this paper, a theoretical model for characterizing solid multi-layered cylindrical samples illuminated by a modulated uniform incident beam is developed by means of the Green function method. The specific Green function for the multi-layered cylindrical structure is derived and an analytical expression for the Thermal-Wave field in such a cylindrical sample is presented. The Thermal-Wave field of an inhomogeneous cylindrical sample irradiated with incident light of arbitrary angular and/or radial intensity distribution was obtained using this theoretical model. Furthermore, experimental validation is also presented in the form of experimental results with steel cylinders of various diameters.
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reconstruction of radial Thermal conductivity depth profile in case hardened steel rods
Journal of Applied Physics, 2009Co-Authors: R Celorrio, A Mendioroz, E Apinaniz, A Salazar, Chinhua Wang, Andreas MandelisAbstract:In this work the surface Thermal-Wave field (ac temperature) of a solid cylinder illuminated by a modulated light beam is calculated first in two cases: a multilayered cylinder and a cylinder the radial Thermal conductivity of which varies continuously. It is demonstrated numerically that, using a few layers of different thicknesses, the surface Thermal-Wave field of a cylindrical sample with continuously varying radial Thermal conductivity can be calculated with high accuracy. Next, an inverse procedure based on the multilayered model is used to reconstruct the radial Thermal conductivity profile of hardened C1018 steel rods, the surface temperature of which was measured by photoThermal radiometry. The reconstructed Thermal conductivity depth profile has a similar shape to those found for flat samples of this material and shows a qualitative anticorrelation with the hardness depth profile.
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case depth determination in heat treated industrial steel products using photoThermal radiometric interferometric phase minima
Ndt & E International, 2007Co-Authors: Chinhua Wang, Andreas MandelisAbstract:A quantitative calibrated methodology based on photoThermal radiometric (PTR) depth-profilometry for non-contact, non-intrusive determination of effective case depth in heat-treated case-hardened steel products was developed. Several types of heat-treated C1018 industrial steel screw products (with hexagonal, cylindrical and spherical heads) are statistically evaluated using the case-depth-induced interferometric Thermal-Wave phase minima. Calibration curves for each type of sample are established with the help of conventional destructive indenter measurements. It is shown that PTR Thermal-Wave interferometric phase minima can be used as a fast, on-line inspection methodology of industrial steel products for non-destructive quality and feedback control of heat-treating processes.
Mathias Kersemans - One of the best experts on this subject based on the ideXlab platform.
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novel discrete frequency phase modulated excitation Waveform for enhanced depth resolvability of Thermal Wave radar
Mechanical Systems and Signal Processing, 2019Co-Authors: Saeid Hedayatrasa, Gaetan Poelman, Joost Segers, Wim Van Paepegem, Mathias KersemansAbstract:Abstract Thermal Wave radar (TWR) is a state-of-the-art non-destructive testing method, inspired by radio Wave radar systems, in order to increase depth resolution and signal to noise ratio of optical infrared thermography through pulse compression. Analogue frequency modulation (i.e. frequency sweep) and Barker binary phase modulation are the two popular and widely researched pulse compression techniques in TWR among which Barker coding has shown the highest performance. This paper introduces a novel modulated Waveform with variable discrete frequency-phase modulation (FPM) which distinctively enhances the depth resolvability of TWR compared to the existing techniques. The pulse compression quality and depth resolvability of the novel FPM Waveform is initially evaluated through a 1D analytical solution. The analogue frequency modulated and discrete phase modulated Waveforms as well as mono-frequency excitation (i.e. lock-in thermography) are also evaluated at the same central frequency as the reference. Objective functions are defined and a large search space is explored for optimal modulation codes. Two FPM Waveforms are selected based on their maximized depth resolvability through resultant lag and phase in the output channel of TWR. Furthermore, the excellent performance of the selected FPM Waveforms is validated by 3D finite element simulation. A delaminated glass fiber reinforced polymer (GFRP) laminate is simulated in order to evaluate the impact of a dominant lateral heat diffusion on the performance of the novel FPM Waveforms. The superior depth resolvability of the introduced FPM Waveforms is confirmed and their robustness at various noise levels is demonstrated.
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performance of frequency and or phase modulated excitation Waveforms for optical infrared thermography of cfrps through Thermal Wave radar a simulation study
Composite Structures, 2019Co-Authors: Saeid Hedayatrasa, Gaetan Poelman, Joost Segers, Wim Van Paepegem, Mathias KersemansAbstract:Abstract Following the developments in pulse compression techniques for increased range resolution and higher signal to noise ratio of radio Wave radar systems, the concept of Thermal Wave radar (TWR) was introduced for enhanced depth resolvability in optical infrared thermography. However, considering the highly dispersive and overly damped behavior of heat Wave, it is essential to systematically address both the opportunities and the limitations of the approach. In this regard, this paper is dedicated to a detailed analysis of the performance of TWR in inspection of carbon fiber reinforced polymers (CFRPs) through frequency and/or phase modulation of the excitation Waveform. In addition to analogue frequency modulated (sweep) and discrete phase modulated (Barker binary coded) Waveforms, a new discrete frequency-phase modulated (FPM) excitation Waveform is introduced. All Waveforms are formulated based on a central frequency so that their performance can be fairly compared to each other and to lock-in thermography at the same frequency. Depth resolvability of the Waveforms, in terms of phase and lag of TWR, is firstly analyzed by an analytical solution to the 1D heat Wave problem, and further by 3D finite element analysis which takes into account the anisotropic heat diffusivity of CFRPs, the non-uniform heating induced by the optical source and the measurement noise. The spectrum of the defect-induced phase contrast is calculated and, in view of that, the critical influence of the chosen central frequency and the laminate’s thickness on the performance of TWR is discussed. Various central frequencies are examined and the outstanding performance of TWR at relatively high excitation frequencies is highlighted, particularly when approaching the so-called blind frequency of a defect.