Lock-in thermography for nondestructive evaluation of materials

Wu, D.; Busse, G.

doi:10.1016/s0035-3159(98)80047-0

Cited by 288 publications

(151 citation statements)

References 12 publications

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“…can be evaluated through its emission in the MWIR range and reconstructed by means of four equidistant data points S i (x,y) recorded over the specimen surface during each modulation period [12]. These four images are then processed in the frequency domain using the Fourier transformation tuned to the frequency of amplitude modulation to gain the magnitude image A(x,y) and the phase image φ (x,y):…”

Section: Qirt 10mentioning

confidence: 99%

Ultrasound lockin thermography as a quantitative technique for quality control assessment of cast iron turbine components

Montanini¹,

Rossi²,

Freni³

2010

Proceedings of the 2010 International Conference on Quantitative InfraRed Thermography

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This paper explores the application of ultrasound activated infrared thermography for the detection and quantification of flaws in industrial cast iron turbocharger components. The use of amplitude modulated ultrasonic heat generation allowed selective response of defected area, since the defect itself is turned into a local thermal wave emitter. Due to the very fast cycle time (< 30 s/part), the method could potentially be applied for 100% quality control of cast parts.After a brief description of the measurement technique and experimental setup used to carry out the tests, main results and discussion are reported. Most emphasis has been addressed to assess the influence of different operative parameters on defect's detection capability as well as accurate sizing of the discontinuity.

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Section: Qirt 10mentioning

confidence: 99%

Ultrasound lockin thermography as a quantitative technique for quality control assessment of cast iron turbine components

Montanini¹,

Rossi²,

Freni³

2010

Proceedings of the 2010 International Conference on Quantitative InfraRed Thermography

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“…Thermographic methods broadly divided into two types: passive , in which the temperature pattern of thesurface of material is measured without any external thermal excitation, and active in which thermal energy is artificially injected in to the material to be tested [1] . Although several methods have been proposed over the years to detect delamination defects in solid materials, three of them are predominantly in use: Pulse Thermography (PT), lock in Thermography (LT) and Pulse Phase Thermography (PPT) [2], [3], [4]. However, none has so far been free from certain limitations: Pulse thermography(PT) requires high peak power heat sources and being sensitive to surface emissivity variations and nonuniform heating on the surface of test sample, lock in Thermography (LT) suffers with limited depth resolution and long processing time [5], [6] and Pulse Phase Thermography (PPT) needs high peak power heat sources to detect deeper subsurface defects, which however may damage the surface of the test sample.…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Testing by Means of Frequency Modulated Infrared Imaging

Kante¹,

Mulaveesala²,

Rama³

et al. 2013

IJCCE

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Abstract-Infrared non-destructive evaluation (IRNDE) is an emerging approach for non-contact inspection of various solid materials such as metals, composites and semiconductors for industrial and research interest. This paper describes the characterization of possible subsurface failures inside Mild steel materials, which are widely used, particularly in the power and steel industries by Frequency Modulated Thermal Wave Imaging(FMTWI). Mild steel specimens with a man made defects were tested by of recently proposed pulse compression based approach. Present work highlights comparative results obtained with both phase and correlation based approaches for defect detection using frequency modulated thermal excitation scheme.Index Terms-Pulse thermography, Lockin thermography, frequency modulated thermal wave imaging, pulse compression and Phase analysis

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“…Modulated or Lock-In Thermography (LT) [9,10] has many similarities with PPT. In fact in LT a phase shift between defected and sound areas is observed on the measured harmonic response of the component, and this phase contrast represents again the defect signature.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore sampling windows containing a multiple number of signal periods can reduce the influence of noise (e.g. leakage or ripple [3]) and the lock-in correlation between pure sinusoidal waves is straight forward in terms of signal processing [9,10]. The second feature represents a drawback compared to PPT since the measured phase shift at the given carrier frequency might not be the optimised value at different defect depths [11].…”

Section: Introductionmentioning

confidence: 99%

Thermal NDE of thick GRP panels by means of a Pulse Modulated Lock-In Thermography technique

Pitarresi

2010

EPJ Web of Conferences

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Abstract. This work describes the development and implementation of an infrared thermal NDE procedure for the evaluation of subsurface defects. The approach is called Pulse-Modulated Lock-In Thermography (PMLT) and is based on the analysis of the frequency response of the measured temperature and comparison with the carrier frequencies launched by the external heat delivering source. The heat deposited on the object is in particular modulated as a train of square waves. This is easily achieved by periodically shuttering the heat source. The temperature is then sampled throughout the deposition of a few square waves. A lock-in algorithm is then implemented able to selectively filter out components at the main carrier frequencies of the heating signal and evaluate the phase information. Defected areas at different depths can be marked based on phase contrast, by using data from a single experiment as in Pulsed-Phase Thermography. An artificially defected thick GRP panel typical of naval monolithic hull structures, is investigated to validate the proposed technique. Experimental data have confirmed the potentials of PMLT as a flexible IR NDT approach, and its ability to be implemented by means of low cost heating and IR equipments.

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Lock-in thermography for nondestructive evaluation of materials

Cited by 288 publications

References 12 publications

Ultrasound lockin thermography as a quantitative technique for quality control assessment of cast iron turbine components

Ultrasound lockin thermography as a quantitative technique for quality control assessment of cast iron turbine components

Non-Destructive Testing by Means of Frequency Modulated Infrared Imaging

Thermal NDE of thick GRP panels by means of a Pulse Modulated Lock-In Thermography technique

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