Phase and group velocities for Lamb waves in DOP-26 iridium alloy sheet

Simpson, W.A.; McGuire, Donn

doi:10.2172/10171446

Cited by 4 publications

(4 citation statements)

References 4 publications

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“…One of the major problems in the analysis of signals from ultrasonic sensors is the fact that the signal of interest is often overlapped with many other signals [6]. The feature of interest (such as a localized weld defect) produces a signal that contains desired information (such as the distance of the weld defect from the point of ultrasonic excitation).…”

Section: Laser Ultrasonicsmentioning

confidence: 99%

In-Process Detection of Weld Defects Using Laser-Based Ultrasonic Lamb Waves

Kercel¹

2001

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Section: Laser Ultrasonicsmentioning

confidence: 99%

In-Process Detection of Weld Defects Using Laser-Based Ultrasonic Lamb Waves

Kercel¹

2001

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“…One of the major problems in the evaluation of signals from ultrasonic sensors is the fact that the signal of interest is often overlapped with many other 12 The feature of interest (such as a localized weld defect) produces a signal that contains desired information (such as the distance of the weld defect from the point of ultrasonic excitation). However, other features (such as the edges of the workpiece) also produce signals that overlap the signal of interest, but contain no relevant information.…”

Section: Signal Overlapmentioning

confidence: 99%

<title>Bayesian separation of Lamb wave signatures in laser ultrasonics</title>

Kercel

Klein²,

Pouet³

2000

SPIE Proceedings

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Laser-based ultrasonic (LBU) measurement shows great promise for on-line monitoring of weld quality in tailor-welded blanks. Tailor-welded blanks are steel blanks made from plates of differing thickness and/or properties butt-welded together; they are used in automobile manufacturing to produce body, frame, and closure panels. LBU uses a pulsed laser to generate the ultrasound and a continuous wave (CW) laser interferometer to detect the ultrasound at the point of interrogation to perform ultrasonic inspection. LBU enables in-process measurements since there is no sensor contact or near-contact with the workpiece. The authors are using laser-generated plate (Lamb) waves to propagate from one plate into the weld nugget as a means of detecting defects.A persistent problem in the analysis of Lamb wave signatures in experimental data is the fact that several different modes appear simultaneously in the signal. The modes overlap in both frequency and time domains. Attempts to separate the overlapping Lamb wave signatures by conventional signal processing methods have been unsatisfactory. This paper reports an exciting alternative to conventional methods. Severely overlapping Lamb waves are found to be readily separable by Bayesian parameter estimation. The authors have used a linear-chirped Gaussian-windowed sinusoid as a model of the Lamb wave mode. For signatures captured in laser ultrasonic data in tailor-welded blanks, this has led to straightforward separation of multiple modes. Furthermore, the resulting parameter sets for the different modes reveal crucial characterizing features of the properties ofthe workpiece.

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“…6 The feature of interest (such as a localized weld defect) produces a signal that contains desired information (such as the distance of the weld defect from the point of ultrasonic excitation). However, other features (such as the edges of the workpiece) also produce signals that overlap the signal of interest, but contain no relevant information.…”

Section: Signal Overlapmentioning

confidence: 99%

<title>In-process detection of weld defects using laser-based ultrasound</title>

Kercel

Kisner

Klein³

et al. 1999

SPIE Proceedings

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Laser-based ultrasonic (LBU) measurement shows great promise for on-line monitoring of weld quality in tailor-welded blanks. Tailor-welded blanks are steel blanks made from plates of differing thickness and/or properties butt-welded together; they are used in automobile manufacturing to produce body, frame, and closure panels. LBU uses a pulsed laser to generate the ultrasound and a continuous wave (CW) laser interferometer to detect the ultrasound at the point of interrogation to perform ultrasonic inspection. LBU enables in-process measurements since there is no sensor contact or near-contact with the workpiece.The authors are using laser-generated plate (Lamb) waves to propagate from one plate into the weld nugget as a means of detecting defects. This paper reports the results of the investigation of a number of inspection architectures based on processing of signals from selected plate waves, which are either reflected from or transmitted through the weld zone. Bayesian parameter estimation and wavelet analysis (both continuous and discrete) have shown that the LBU time-series signal is readily separable into components that provide distinguishing features which describe weld quality. The authors anticipate that, in an on-line industrial application, these measurements can be implemented just downstream from the weld cell. Then the weld quality data can be fed back to control critical weld parameters or alert the operator of a problem requiring maintenance. Internal weld defects and deviations from the desired surface profile can then be corrected before defective parts are produced.

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Phase and group velocities for Lamb waves in DOP-26 iridium alloy sheet

Cited by 4 publications

References 4 publications

In-Process Detection of Weld Defects Using Laser-Based Ultrasonic Lamb Waves

In-Process Detection of Weld Defects Using Laser-Based Ultrasonic Lamb Waves

<title>Bayesian separation of Lamb wave signatures in laser ultrasonics</title>

<title>In-process detection of weld defects using laser-based ultrasound</title>

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