Potential and limitations of eddy current lockin-thermography

Riegert, G.; Gleiter, Andreas; Busse, G.

doi:10.1117/12.662716

Cited by 20 publications

(13 citation statements)

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“…The relative temperature contrast can be calculated for this case as C R (t) = T crack (t) − T sound (t) T sound (t) = α √ π Ei α 2 + er f (α) (5) where α denotes the ratio…”

Section: The Modelsmentioning

confidence: 99%

“…The working group around Busse investigated induction thermography to detect subsurface defects in steel and in CFRP (carbon fiber reinforced polymer) samples in a modulated way (lock-in technique) and with pulse heating (burst thermography) [4]. Aluminum fatigue surface cracks have been also detected using the lock-in technique [5]. Analytical and numerical models [6][7][8] have been set up for modeling cracks perpendicular to the surface in steel materials.…”

Section: Introductionmentioning

confidence: 99%

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Induction Thermography for Surface Crack Detection and Depth Determination

Oswald-Tranta

2018

Applied Sciences

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Abstract:In the last few years, induction thermography has been established as a non-destructive testing method for localizing surface cracks in metals. The sample to be inspected is heated with a short induced electrical current pulse, and the infrared camera records-during and after the heating pulse-the temperature distribution at the surface. Transforming the temporal temperature development for each pixel to phase information makes not only highly reliable detection of the cracks possible but also allows an estimation of its depth. Finite element simulations were carried out to investigate how the phase contrast depends on parameters such as excitation frequency, pulse duration, material parameters, crack depth, and inclination angle of the crack. From these results, generalized functions for the dependency of the phase difference on all these parameters were derived. These functions can be used as an excellent guideline as to how measurement parameters should be optimized for a given material to be able to detect cracks and estimate their depth. Several experiments on different samples were also carried out, and the results compared with the simulations showed very good agreement.

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“…The relative temperature contrast can be calculated for this case as C R (t) = T crack (t) − T sound (t) T sound (t) = α √ π Ei α 2 + er f (α) (5) where α denotes the ratio…”

Section: The Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Induction Thermography for Surface Crack Detection and Depth Determination

Oswald-Tranta

2018

Applied Sciences

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“…In 2011, it was applied to image multiple RCF cracks on rail for the first time [12]. Many researchers have proposed various ECT methods, such as thermal-inductive [13], electromagnetic-thermal [14], tone burst eddy current thermography (TBET) [15], eddy current pulsed thermography (ECPT) [10,[16][17][18][19][20], induction thermography [21], eddy current lock-in thermography (ECLT) [22], eddy current pulsed phase thermography [11] (or inductive pulsed phase thermography [23]) and eddy current step heating thermography [24]. Among these works, the methods for defect detection can be classified into two groups.…”

Section: Introductionmentioning

confidence: 99%

Lateral heat conduction based eddy current thermography for detection of parallel cracks and rail tread oblique cracks

Yang

Gao

et al. 2015

Measurement

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“…The distribution and the pattern of the heat diffusion can be interpreted to locate defects. The progress of active thermography in recent years was not only driven by the technology of the infrared cameras used to image the evolution of surface temperature but also the large number of excitation techniques available to choose from for a specific application [1,2,5,7].…”

Section: Principle Of Operationmentioning

confidence: 99%

Automated Induction Thermography of Generator Components

Goldammer¹,

Mooshofer²,

Rothenfusser³

et al. 2010

AIP Conference Proceedings

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Using Active Thermography defects such as cracks can be detected fast and reliably. Choosing from a wide range of excitation techniques the method can be adapted to a number of tasks in non-destructive evaluation. Induction thermography is ideally suited for testing metallic components for cracks at or close to the surface. In power generation a number of components are subjected to high loads and stresses -therefore defect detection is crucial for a safe operation of the engines. Apart from combustion turbines this also applies to generators: At regular inspection intervals even small cracks have to be detected to avoid crack growth and consequently failure of the component. As an imaging technique thermography allows for a fast 100% testing of the complete surface of all relevant parts. An automated setup increases the cost effectiveness of induction thermography significantly. Time needed to test a single part is reduced, the number of tested parts per shift is increased, and cost for testing is reduced significantly. In addition, automation guarantees a reliable testing procedure which detects all critical defects. We present how non-destructive testing can be automated using as an example an industrial application at the Siemens sector Energy, and a new induction thermography setup for generator components.

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Potential and limitations of eddy current lockin-thermography

Cited by 20 publications

References 0 publications

Induction Thermography for Surface Crack Detection and Depth Determination

Induction Thermography for Surface Crack Detection and Depth Determination

Lateral heat conduction based eddy current thermography for detection of parallel cracks and rail tread oblique cracks

Automated Induction Thermography of Generator Components

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