Measurement of the scattering of a Lamb wave by a through hole in a plate

Fromme, Paul; Sayir, Mahir

doi:10.1121/1.1448338

Cited by 100 publications

(70 citation statements)

References 20 publications

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“…In order to avoid the complication of multiple wave modes, the maximum excitation frequency is often chosen well below the lowest cut-off frequency of the higher wave modes [16], in which the relative out-of-plane component of the S 0 mode is also rather small. For the 5-mm thick steel plate used in the laboratory experiments (Section IV), this limits the maximum frequency range to about 250 kHz, and gives a minimum wavelength in the order of 10 mm.…”

Section: A Transducer Design Requirementsmentioning

confidence: 99%

On the development and testing of a guided ultrasonic wave array for structural integrity monitoring

Fromme¹,

Wilcox²,

Lowe³

et al. 2006

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

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Abstract-The prototype of a guided ultrasonic wave array for the structural integrity monitoring of large, platelike structures has been designed, built, and tested. The development of suitably small transducers for the excitation and measurement of the first antisymmetric Lamb wave mode A0 is described. The array design consists of a ring of 32 transducers, permanently bonded to the structure with a protective membrane, in a compact housing with the necessary multiplexing electronics. Using a phased addition algorithm with dispersion compensation and deconvolution in the wavenumber domain, a good dynamic range can be achieved with a limited number of transducers. Limitations in the transducer design and manufacture restricted the overall dynamic range achieved to 27 dB. Laboratory measurements for a steel plate containing various defects have been performed. The results for standard defects are compared to theoretical predictions and the sensitivity of the array device for defect detection has been established. Simulated corrosion pitting and a defect cut with an angle grinder simulating general corrosion were detected.

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Section: A Transducer Design Requirementsmentioning

confidence: 99%

On the development and testing of a guided ultrasonic wave array for structural integrity monitoring

Fromme¹,

Wilcox²,

Lowe³

et al. 2006

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

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“…The reflection of the propagating wave at defects enables rapid detection of defects in large structures [14]. This method has been used successfully for the detection of defects in large metal plates and long pipes, i.e., for corrosion and crack detection [15]. However, the behaviour of the guided waves is somewhat more complicated in composite structures owing to the physical properties of composites that are generally inhomogeneous and anisotropic in nature.…”

Section: Introductionmentioning

confidence: 99%

Propagation and scattering of guided waves in composite plates with defects

Murat

Fromme

2016

Int. J. Automot. Mech. Eng.

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Failure in aerospace composites owing to low-velocity impact raises a significant maintenance concern because it can lead to invisible damage. For the aerospace industry, such defects pose a potential danger to the structural integrity of aircraft. This in turn jeopardises passenger safety and incurs high repair costs. Hence, it is important to efficiently monitor composite structures during the service life. In this study, the potential of low-frequency guided ultrasonic waves for health monitoring in laminated composite plates is investigated. This study focuses on the use of the first antisymmetric guided wave mode (A0). The first part of this study is to investigate the propagation of the A0 mode in three different undamaged composite plates experimentally. The dispersive and anisotropic behaviour are in agreement with the results of finite element simulations and semi-analytical analysis. The final part of this study presents the scattering of guided waves at the impact damage using a non-contact laser interferometer. Significant scattering activities were observed and the impact damage size can be estimated to be about 10 × 25 mm. In conclusion, these results demonstrate the potential of guided ultrasonic waves for the inspection of aerospace composite structures.

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“…The velocity of the out-of-plane displacement was measured using a laser interferometer every 5 degrees on a circle around the notch with a radius of 30 mm. The full time traces of the measured signals were bandpass filtered (75 kHz -125 kHz) and averaged in a digital oscilloscope before being transferred to the measurement PC [13]. Similar to the FE simulations, an initial measurement was done for each excitation transducer before the milling of the notch to capture the incident wave field, and then for each notch depth.…”

Section: Methodsmentioning

confidence: 99%

“…Additional simulations were run to capture the incident wave field only, without a defect present. Taking the difference between the complex magnitudes for each point with and without a defect, the amplitude of the wave scattered at the defect can be isolated [13]. The amplitude of the scattered wave was extracted on a radius of 30 mm by interpolating between monitoring nodes to obtain an amplitude value every 5 degree.…”

Section: Finite Element Simulationmentioning

confidence: 99%

“…The scattering of the A0 Lamb wave mode at a through thickness hole [13], part thickness hole [14], 2D notch [15] and fatigue crack emanating from a fastener hole has been reported previously [16]. Continuing from previous contributions [17][18][19], the directionality pattern of the A0 Lamb wave mode scattered at crack-like defects (notch) in a plate is investigated, depending on the angle of the incident wave relative to the crack orientation and on the defect length relative to the wavelength.…”

Section: Introductionmentioning

confidence: 99%

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