Detection of structural damage from the local temporal coherence of diffuse ultrasonic signals

Michaels, Jennifer E.; Michaels, Thomas E.

doi:10.1109/tuffc.2005.1561631

Cited by 184 publications

(161 citation statements)

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“…To first order, global velocity changes in the medium result in a stretching of the waveforms [10,[14][15][16] but the interpretation of a local change in terms of travel time fluctuation remains problematic. Recently DAWS has been used in damage monitoring [17,18] but a large range of other applications are possible [19]. For a broad review of applications of CWI in geophysics, we refer to [20].…”

Section: Introductionmentioning

confidence: 99%

Locating a weak change using diffuse waves: Theoretical approach and inversion procedure

Rossetto

Margerin

Planès

et al. 2011

Journal of Applied Physics

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We describe a time-resolved monitoring technique for heterogeneous media. Our approach is based on the spatial variations of the cross-coherence of coda waveforms acquired at fixed positions but at different dates. To locate and characterize a weak change that occurred between successive acquisitions, we use a maximum likelihood approach combined with a diffusive propagation model. We illustrate this technique, called LOCAD-IFF, with numerical simulations. In several illustrative examples, we show that the change can be located with a precision of a few wavelengths and its effective scattering cross-section can be retrieved. The precision of the method depending on the number of source receiver pairs, time window in the coda, and errors in the propagation model is investigated. Limits of applications of the technique to real-world experiments are discussed.

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Section: Introductionmentioning

confidence: 99%

Locating a weak change using diffuse waves: Theoretical approach and inversion procedure

Rossetto

Margerin

Planès

et al. 2011

Journal of Applied Physics

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“…However, it is impractical to have a database covering all environmental conditions at a small enough temperature step. The Optimal Stretch method is another common technique [18,19], which uses a signal processing method to compensate for the temperature difference. As shown in Eq.…”

Section: Temperature Compensation Methodsmentioning

confidence: 99%

Feasibility and Reliability of Grain Noise Suppression in Monitoring of Highly Scattering Materials

Liu

Pamel

et al. 2017

J Nondestruct Eval

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A feasibility study on grain noise suppression using baseline subtraction is presented in this paper. Monitoring is usually done with permanently installed transducers but this is not always possible; here instead monitoring is conducted by carrying out repeat C-scans and the feasibility of grain noise suppression by subtracting A-scans extracted from the C-scans is investigated. The success of this technique depends on the ability to reproduce the same conditions for each scan, including a consistent stand-off, angle, and lateral position of the transducer relative to the testpiece. The significance of errors are illustrated and a 3D cross correlation is used which enables the same lateral position to be located within successive C-scans. The experimental results show that a noise reduction of around 15 dB is obtained after baseline subtraction, which will significantly improve the defect detection sensitivity. In practice however, successive C-scans may be conducted at different temperatures and with different transducers of similar specifications but a varying frequency response. Compensation techniques to reduce the impact of such variations are then presented and their effectiveness is verified experimentally. It is shown that it is feasible to obtain an overall improvement of around 10 dB in the signal to noise ratio via baseline subtraction, where a temperature difference of up to 10 • C and a peak frequency shift of as much as ±250 kHz from a baseline value of around 7 MHz can be tolerated. However, this improvement was obtained in laboratory conditions with no changes to the surface of the specimen due to oxidation or corrosion. It is shown that differences in tem-B Yuan Liu y.liu14@imperial.ac.uk 1 NDE Group, Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK perature and transducer frequency response are more difficult to compensate for than changes in test geometry and position.

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“…However, these methods cannot as easily be applied to irregular geometries, such as bolted joints, stiffened ribs, or curve panels, because of mode conversion and wave interference effects that arise as a result of the complex interfaces and mechanical impedance mismatches in these constructions. Instead, some researchers have attempted to employ bulk insonification, where an ultrasonic source is excited and the resultant long-time, or diffuse, wave field is examined to identify structural changes (Michaels and Michaels, 2005). This method is complementary to GUW mode-locked analyses for structures with complex boundary conditions or geometries that make tracking and analysis of a single propagating mode difficult or impossible.…”

Section: Chaotically-modulated In Nullification and Time Series Predimentioning

confidence: 99%

“…However, structural geometries such as highly curved regions, bolted interfaces, etc., pose significant modeling and testing challenges for GUWs, resulting in difficulty in classifying size or type of damage due to the inherent simplicity of the actively imparted excitation signal, which is usually a modulated, narrow-band, short-wave pulse. Instead, some researchers have attempted to employ bulk insonification, where an ultrasonic source is excited, and the resultant long-time, or diffuse, wave field is examined to identify structural changes (Michaels and Michaels, 2005). This method is investigated as well to augment the standard guided wave method for structures with complex boundary conditions or geometries that make tracking and analysis of a single propagating mode difficult or impossible.…”

Section: Introductionmentioning

confidence: 99%

Proof-of-Concept Studies in Novel Guided Wave Methods for Metallic Structural Condition

Todd¹,

Scalea²

2009

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)The Regents of the University of California; University of California, San Diego 9500 Gilman Drive, Mail Code 0934 LaJolla,CA 92093-0934 PERFORMING ORGANIZATION REPORT NUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Office of Naval Research 875 North Randolph Street Arlington, VA 22203-1995 SPONSOR/MONITOR'S ACRONYM(S) ONR SPONSOR/MONITORS REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTB. Approved for public release; distribution unlimited. SUPPLEMENTARY NOTES ABSTRACTActive sensing in structural health monitoring (SHM) refers to injecting (user-defined) energy into the system in order to actively probe its response to the induced dynamics as a means of detecting whether damage may be present in the system. A number of researchers have shown that active sensing with guided ultrasonic waves (GUWs) can be a powerful approach to take, as GUWs, when launched and detected in conjunction with macro-fiber composite (MFC) patches, can retain the wide area coverage capability of lower frequency (vibration) methods while significantly enhancing sensitivity to flaws (cracks, corrosion, etc.) because of the small interrogating wavelengths used.This project, led by PI Michael Todd and Co-PI Francesco Lanza di Scalea, considered several new concepts in guided GUWs: (i) optimized passive GUWs, (ii) quantitative active GUWs, and (iii) a generalized insonification (diffuse field) approach rooted in data-based modeling and pattern recognition. These concepts are tested on metallic test articles to detect a variety of defects, including impact damage, simulated cracks (notching), corrosion, and bolted joint preload loss. ABSTRACT Active sensing in structural health monitoring (SHM) refers to injecting (user-defined) energy into the system in order to actively probe its response to the induced dynamics as a means of detecting whether damage may be present in the system. A number of researchers have shown that active sensing with guided ultrasonic waves (GUWs) can be a powerful approach to take, as GUWs, when launched and detected in conjunction with macro-fiber composite (MFC) patches, can retain the wide area coverage capability of lower frequency (vibration) methods while significantly enhancing sensitivity to flaws (cracks, corrosion, etc.) because of the small interrogating wavelengths used.This project, led by PI Michael Todd and Co-PI Francesco Lanza di Scalea, considered several new concepts in guided GUWs: (i) optimized passive GUWs, (ii) quantitative active GUWs, and (iii) a generalized insonification (diffuse field) approach root...

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Detection of structural damage from the local temporal coherence of diffuse ultrasonic signals

Cited by 184 publications

References 18 publications

Locating a weak change using diffuse waves: Theoretical approach and inversion procedure

Locating a weak change using diffuse waves: Theoretical approach and inversion procedure

Feasibility and Reliability of Grain Noise Suppression in Monitoring of Highly Scattering Materials

Proof-of-Concept Studies in Novel Guided Wave Methods for Metallic Structural Condition

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