The transmission of Lamb waves across adhesively bonded lap joints

Lowe, M. J. S.; Challis, R.E.; Chan, C. W.

doi:10.1121/1.428420

Cited by 129 publications

(94 citation statements)

References 20 publications

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“…1. An ultrasonic pulse with a frequency of 100kHz was applied to the top of the bar as pressure following a sinusoidal function as presented by Yagawa and Okuda [4], although in this case two periods of the sine function were used [6,7]. The maximum amplitude of the pulse was 10MPa.…”

Section: Finite Element Analysismentioning

confidence: 99%

A Neural Network Approach for Locating Multiple Defects

Farley

Durodola

Fellows

et al. 2008

AMM

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A method is presented to demonstrate the use of artificial neural networks (ANNs) in providing additional information regarding defects or flaws when used in conjunction with the ultrasonic A-scan method. ANNs were employed both as pattern classifiers and as function approximators to maximise the amount of data available from the temporal A-scan signal. A steel bar was modelled in 2D using ABAQUS finite element analysis (FEA) software. A single defect was introduced to the bar, modelled as a void, and parametric studies conducted to record data with the defect at various locations. An ultrasonic Lamb wave was introduced at the top of the bar. The longitudinal wave propagated along the length of the bar and was partially reflected by the defect. Multiple cases were simulated, modelling voids between 1mm and 6mm in width in various locations. Mean displacement of all the nodes at the top of the bar was recorded throughout the simulation, and features extracted from this waveform to create the data set for the ANNs. The ANNs were trained with a percentage of the data collected, selected at random, and assessed with the remaining data. The target data for the ANNs were the depth and size of the defect. The case of two separate defects was also investigated. The procedure was carried out in the same manner as for one defect, but in this case the target data for the ANNs were the depth of the first defect and the distance between the defects. A separate ANN was employed as a pattern classifier, to determine if the reflected A-scan signal represented one or two defects. The final system was tested using previously unseen data, and provided very good results both in determining the number of defects and the size and location of the defects, even with data to which noise had been added.

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Section: Finite Element Analysismentioning

confidence: 99%

A Neural Network Approach for Locating Multiple Defects

Farley

Durodola

Fellows

et al. 2008

AMM

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“…Different studies [16][17][18][19] have been carried out to investigate the possibility of using Lamb waves to detect defects in complex structures made from isotropic materials. Numerical simulations using finite element (FE) method and experimental measurements have been investigated in the literature.…”

Section: A Lamb Waves In Complex Structuresmentioning

confidence: 99%

Scattering characteristics of Lamb waves from debondings at structural features in composite laminates

Veidt

2012

The Journal of the Acoustical Society of America

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This article investigates the scattering characteristics of Lamb waves from a debonding at a structural feature in a composite laminate. This study specifically focuses on the use of the low frequency fundamental antisymmetric (A0) Lamb wave as the incident wave for debonding detection. Three-dimensional finite element (FE) simulations and experimental measurements are used to investigate the scattering phenomena. Good agreement is obtained between the FE simulations and experimental results. Detailed parameter studies are carried out to further investigate the relationship between the scattering amplitudes and debonding sizes. The results show that the amplitude of the scattered A0 Lamb wave is sensitive to the debonding size, which indicates the potential of using the low frequency A0 Lamb wave as the interrogating wave for debonding detection and monitoring. The findings of the study provide improved physical insights into the scattering phenomena, which are important to further advance damage detection techniques and optimize transducer networks.

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“…Various NDE (nondestructive evaluation) techniques have been suggested to monitor bonded joints based on ultrasonic, acoustic, thermal and backface strain measurements [e.g. [1][2][3][4]. Among NDE optical techniques suggested, the use of uniform fibre Bragg grating (FBG) sensors has been the most widely favoured, with a number of 2 demonstrations available in the literature for monitoring bonded joints, repairs and structures [e.g.…”

Section: Introductionmentioning

confidence: 99%

Disbond growth detection in composite–composite single-lap joints using chirped FBG sensors

Palaniappan

Ogin

Thorne

et al. 2008

Composites Science and Technology

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Adhesively bonded composite-composite single-lap joints, with cross-ply GFRP adherends, have been cyclically loaded to initiate disbonding at either end of the overlap length. Disbond initiation and growth have been monitored using a combination of in situ photography (the joint is transparent) and a single chirped fibre Bragg grating (CFBG) sensor embedded within one composite adherend (with the low-wavelength end of the sensor adjacent to the cut end) and not in the adhesive bondline. Sensors having the same spectral bandwidth (20 nm), and lengths in the range 15 mm to 60 mm have been tested. The experimental results have been modelled using a combination of finite-element analysis and commercial software for predicting FBG spectra, and the predictions are in very good agreement with the experimental results. In all cases, it has been shown that the position of the disbond front can be located using the CFBG sensors with a precision of about 2 mm.

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The transmission of Lamb waves across adhesively bonded lap joints

Cited by 129 publications

References 20 publications

A Neural Network Approach for Locating Multiple Defects

A Neural Network Approach for Locating Multiple Defects

Scattering characteristics of Lamb waves from debondings at structural features in composite laminates

Disbond growth detection in composite–composite single-lap joints using chirped FBG sensors

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