Shearography: A Tool for Imaging Lamb Waves in Composites and their Interaction with Delaminations

Krapez, Jean-Claude; Taillade, Frédéric; Lamarque, T.; Balageas, D.

doi:10.1007/978-1-4615-4791-4_116

Cited by 6 publications

(7 citation statements)

References 7 publications

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“…Shearography and electronic speckle pattern interferometry have been reported as tools for elastic wave imaging in few papers . Nevertheless, the main application of these methods is flaw and debond detection , which is based on registered deformation anomalies induced by thermal loading or dynamic vibration excitation.…”

Section: Full Wavefield Measurement Techniquesmentioning

confidence: 99%

50th Anniversary Article: Comparison Studies of Full Wavefield Signal Processing for Crack Detection

Ostachowicz

Radzieński

Kudela

2014

Strain

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The signals acquired by measurements of elastic wave propagation have been used for damage detection since the 1970s. The measurements have been carried out mostly by using piezoelectric transducers of various types. Many different sensor configurations and data processing have been proposed to detect and localise structural defects, both for real‐time and off‐line testing. Nevertheless, in the last decade, significant progress in the measurement techniques such as scanning laser Doppler vibrometry and shearographic interferometry has been made. These techniques enable measurement of a full wavefield of elastic waves. This opens up new possibilities and solutions for the problems of the damage detection in structures. Many researchers successfully applied this type of measurements for the damage detection and localisation in thin‐walled structures. Moreover, advanced signal processing techniques, such as wavenumber filtering, give the possibility of damage size estimation, by filling the gap between damage detection and damage prognosis. The aim of this paper is to give a comprehensive review of methods used for the full wavefield measurement. It also describes and compares selected signal processing algorithms developed for damage detection and visualisation based on these measuring techniques. Criticism aspects, as well as advantages of each algorithm, are denoted based on the authors' expertise in the field.

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Section: Full Wavefield Measurement Techniquesmentioning

confidence: 99%

50th Anniversary Article: Comparison Studies of Full Wavefield Signal Processing for Crack Detection

Ostachowicz

Radzieński

Kudela

2014

Strain

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“…Electronic shearography is a common path interferometer that measures the differential displacements of the surface being monitored; TV holography directly measures the displacement of the surface. This distinction means that shearography does not require the levels of vibration isolation required for holography [29]- [32]. However, because shearography measures differential displacements between points separated by the "shearing distance", the optical amplitude is no longer directly proportional to the out-of-plane surface displacement.…”

Section: Discussionmentioning

confidence: 99%

“…Because of this common path design, shearography has a number of advantages over holographic techniques, including tolerance to rigid body motion, reduced laser coherence requirements, compact design, and convenient sensitivity control. Recently, this technique has been used to image modes of bar vibration [29]- [31], ultrasonic waves in plates [29]- [32], and ultrasonic Lamb waves scattered by defects in aluminum plates [31] and C/epoxy plates [32].…”

Section: Introductionmentioning

confidence: 99%

Quantitative flaw reconstruction from ultrasonic surface wavefields measured by electronic speckle pattern interferometry

Mast

Gordon

2001

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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A new method for imaging flaws in plate and shell structures is presented. The method employs twodimensional ultrasonic surface wave data obtained by optical electronic speckle pattern interferometry (ESPI) techniques. In the imaging method, the measured out-of-plane displacement field associated with an externally excited ultrasonic Lamb wave is processed to obtain the spatial frequency domain spectrum of the wavefield. A free space Green's function is then deconvolved from the wavefield to obtain quantitative images of effective scattering sources. Because the strength of these effective sources is directly dependent on local variations in sample thickness and material properties, these images provide a direct map of internal inhomogeneities. Simulation results show that the method accurately images flaws for a wide range of sizes and material contrast ratios. These results also demonstrate that flaw features much smaller than an acoustic wavelength can be imaged, consistent with the theoretical capability of the imaging method to employ scattered evanescent waves. Reconstructions are also obtained from ultrasonic Lamb wave displacement fields recorded by ESPI in a flawed aluminum plate. These reconstructions indicate that the present method has potential for imaging flaws in complex structures for which ESPI wavefield measurements cannot be straightforwardly interpreted.

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“…In these conditions, the shearographic image level is strictly equal to four times the ultrasound amplitude, with sensitivity of the order of one nanometer. If the shear is equal to the wavelength, then the wave is not seen, the deformation of the interfering points being identical, which can be interesting to visualize the waves diffracted by a damage [25,26].…”

Section: B) Synchronization Between the Signal Feeding The Emitter And The Laser Illumination Producing The Stroboscopic Effect C) Synchrmentioning

confidence: 99%

Nondestructive Evaluation of Cooperative Structures (NDECS)

Balageas

2008

Encyclopedia of Structural Health Monitoring

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SHM is born from the conjunction of several techniques and has common basis with NDE. In fact, several NDE techniques can be converted into SHM techniques by integrating the sensors and the actuators inside the monitored structure. NDE is mature, since several decades of research and development have been made. Contrariwise, SHM just begins to come out from laboratories, and applications at a wide scale remain a long-term objective. In these conditions, we may wander if an intermediate way, less performing but feasible at a shorter term, would not be an attractive and relevant position.This third way consists in only embedding at well-chosen locations into the structure the stimulation (actuators or emitters) and leaving the detection (receivers or sensors) outside. To optimize such a system, Lamb waves could be used for the emission and full-field real time imaging techniques used for the reception. So, using the more recent and promising techniques of both domains -SHM and NDE -, the proposed technique could be applied at a short term, with existing technologies and would permit time and money saving for maintenance operations. A well-suited appellation for this type of technique could be: Non-Destructive Evaluation of Cooperative Structures (NDECS).The principle and first validation experiments of two possible NDECS systems, stroboscopic shearography and lock-in ultrasonic vibrothermography, imaging Lamb waves generated by embedded piezoelectric patches, are presented.

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Shearography: A Tool for Imaging Lamb Waves in Composites and their Interaction with Delaminations

Cited by 6 publications

References 7 publications

50th Anniversary Article: Comparison Studies of Full Wavefield Signal Processing for Crack Detection

50th Anniversary Article: Comparison Studies of Full Wavefield Signal Processing for Crack Detection

Quantitative flaw reconstruction from ultrasonic surface wavefields measured by electronic speckle pattern interferometry

Nondestructive Evaluation of Cooperative Structures (NDECS)

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