The low frequency reflection characteristics of the fundamental antisymmetric Lamb wave a0 from a rectangular notch in a plate

Lowe, M. J. S.; Cawley, P.; Kao, J. Y.; Diligent, O.

doi:10.1121/1.1512702

Cited by 194 publications

(120 citation statements)

References 23 publications

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“…Different research activities have been conducted to study the interaction of Lamb waves at different types of damage in various materials. A number of developments [8][9][10] have been achieved for isotropic materials. In recent years, the use of fiber-reinforced composite laminates has steadily increased in engineering applications, such as aerospace, civil, maritime, and automotive, because of their high specific stiffness, light weight, and corrosion resistance as compared with traditional metallic materials.…”

Section: Introductionmentioning

confidence: 99%

Scattering of the fundamental anti-symmetric Lamb wave at delaminations in composite laminates

Veidt

2011

The Journal of the Acoustical Society of America

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An analysis of the scattering characteristics of the fundamental anti-symmetric (A0) Lamb wave at a delamination in a quasi-isotropic composite laminate is presented. Analytical solutions for this problem do not exist due to the anisotropic nature and multilayer characteristics of composite laminates. This study uses a three-dimensional finite element (FE) method and experimental measurements to provide physical insight into the scattering phenomena. Good agreement is found between simulations and experimental measurements. The results show that the A0 Lamb wave scattering at a delamination in composite laminates is much more complicated than the scattering at a defect in isotropic plates. Scatter amplitudes and scatter directivity distributions depend on the delamination size to wavelength ratio and the through-thickness location of the delamination damage. The study also investigates the feasibility of the common experimental practice of simulating delamination damage by bonding masses to the surface of composite laminates for guided wave damage detection and characterization methodologies verifications. The results suggest that care is required to use bonded masses to simulate delamination damage for verifying and optimizing damage characterization techniques. In summary, the results of the investigation help to further advance the use of the A0 Lamb wave for damage detection and characterization.

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Section: Introductionmentioning

confidence: 99%

Scattering of the fundamental anti-symmetric Lamb wave at delaminations in composite laminates

Veidt

2011

The Journal of the Acoustical Society of America

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“…The branches corresponding to each Lamb mode are clearly identifiable. The Rayleigh-Lamb frequency equations can be written as [1] where +1 applies for symmetric modes, while -1 applies It is well known that Lamb wave modes are sensitive to different types of damage (7,8,9). Whereas the S0 mode is characterized by its dominant stress and displacement components in the direction of propagation, the A0 mode has significant shear stress and lateral displacement components.…”

Section: Resultsmentioning

confidence: 99%

Generación de ondas de Lamb en estructuras tipo placa mediante cerámicas piezoeléctricas

Gómez-Ullate¹,

Saletes²,

Espinosa³

2006

Bol. Soc. Esp. Ceram. Vidr.

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In this work, Lamb waves have been generated in a thin aluminum plate by bonding a piezoceramic actuator onto the plate. The acoustic pressure immediately above the plate was measured by a needle hydrophone, coupled to the plate through a thin oil layer, across several centimeters. Use of a 2D FFT algorithm then provides the dispersion curves which compare well to the analytical solution calculated using the dispersion equation. Next, the Lamb modes were selectively reinforced or cancelled by bonding another piezoceramic to the plate at an appropriate location. If the second actuator is excited in phase with the first one the symmetric mode, S0, can be reinforced whereas the antisymmetric mode, A0, is partially cancelled. If the two actuators are excited out of phase, the A0 mode is then enhanced respect to the S0 mode.Keywords: Lamb Waves, piezoceramic, dispersion curves, NDT. Generación de ondas de Lamb en estructuras tipo placa mediante cerámicas piezoeléctricas.En este trabajo se han utilizado cerámicas piezoeléctricas para generar ondas de Lamb en estructuras tipo placa. Se midió la presión acústica a lo largo de unos centímetros de la placa mediante un hidrófono acoplado a ésta mediante una fina capa de aceite. Aplicando a esta información la trasformada bidimensional de Fourier se obtuvieron las curvas de dispersión experimentales y se compararon con las obtenidas teóricamente. A continuación, los modos de Lamb se reforzaron o cancelaron pegando otra cerámica en la placa en la posición adecuada. Al excitar la segunda cerámica en fase con la primera amplificamos el modo simétrico, S0, mientras que el modo antisimétrico, A0, se ve parcialmente cancelado. Excitando las dos cerámicas en contrafase, reforzamos el modo antisimétrico, A0, respecto del simétrico, S0.Palabras clave: Ondas de Lamb, cerámica piezoeléctrica, curvas de dispersión, END.

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“…In structural health monitoring (SHM) or non-destructive evaluation (NDE) application, most situations seem to lie in between. The Lamb wave interactions with finitesized holes 43 and cracks 44 and the scattering patterns of their combinations have also been studied, 45 whereas the reflectivity coefficients are both angle and frequency dependent. However, the severity of the damage, in reality, might be caused by various factors, such as damage size, Young's modulus change, density change, thickness change, or a combination effect for metals.…”

Section: Discussionmentioning

confidence: 99%

Lamb wave-based subwavelength damage imaging using the DORT-MUSIC technique in metallic plates

Fang

2016

Structural Health Monitoring

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A Lamb wave-based, subwavelength imaging algorithm is developed for damage imaging in a metallic plate based on a decomposition of the time-reversal operator method together with a multiple signal classification imaging condition in the space-frequency domain. In this study, a hybrid non-contact inspection system was proposed to image damage in an aluminum plate using a piezoelectric linear array for actuation and a laser Doppler vibrometer line-scan perpendicular to the piezoelectric array for sensing. The physics of incident waves, reflection, and reflected waves that underlie the transfer matrix in the decomposition of the time-reversal operator method is mathematically formulated in the context of guided waves based on the first-order Born approximation. Singular value decomposition is then employed to decompose the experimentally measured transfer matrix into three matrices, detailing the incident wave propagation from the linear actuator array, reflection from the damage, and followed by reflected waves toward the linear sensing array for each small damage. The singular value decomposition and multiple signal classification imaging condition enable providing insight on both the damage ''reflectivity'' and detecting damage smaller than a wavelength (subwavelength). With the flexibility of this inspection system, a considerably large area can be imaged using lower frequency Lamb waves with rapid line-scans. The experimental results showed that the hardware system with a signal processing tools such as the decomposition of the time-reversal operator with multiple signal classification (time-reversal with multiple signal classification) imaging technique can provide robust, highly accurate imaging results as well as providing damage reflectivity estimation with unknown material properties.

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The low frequency reflection characteristics of the fundamental antisymmetric Lamb wave a0 from a rectangular notch in a plate

Cited by 194 publications

References 23 publications

Scattering of the fundamental anti-symmetric Lamb wave at delaminations in composite laminates

Scattering of the fundamental anti-symmetric Lamb wave at delaminations in composite laminates

Generación de ondas de Lamb en estructuras tipo placa mediante cerámicas piezoeléctricas

Lamb wave-based subwavelength damage imaging using the DORT-MUSIC technique in metallic plates

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