<i>Wave Propagation in Layered Anisotropic Media with Applications to Composites</i>

Nayfeh, Adnan H.

doi:10.1121/1.429576

Cited by 114 publications

(125 citation statements)

References 2 publications

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“…Lamb waves are a form of elastic perturbation that can propagate in a solid plate with free boundaries [25,26]. This type of wave phenomenon was first described in theory by Horace Lamb in 1917, however he never attempted to produce them [27].…”

Section: Description Of Lamb Wavesmentioning

confidence: 99%

Damage detection in composite materials using Lamb wave methods

Spearing

Soutis

2002

Smart Mater. Struct.

671

413

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Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in-situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasiisotropic graphite/epoxy test specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Linear wave scans were performed on narrow laminated specimens and sandwich beams with various cores by monitoring the transmitted waves with piezoceramic sensors (PZT). Optimal actuator and sensor configurations were devised through experimentation, and various types of driving signals were explored. These experiments provided a procedure capable of easily and accurately determining the time-of-flight of a Lamb wave pulse between an actuator and sensor. Lamb wave techniques provide more information about damage presence and severity than previously tested methods (frequency response techniques), and provide the possibility of determining damage location due to their local response nature. These methods may prove suitable for structural health monitoring applications since they travel long distances and can be applied with conformable piezoelectric actuators and sensors that require little power.

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Section: Description Of Lamb Wavesmentioning

confidence: 99%

Damage detection in composite materials using Lamb wave methods

Spearing

Soutis

2002

Smart Mater. Struct.

671

413

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“…Moreover, when this in-plane angle does not coincide with one of the symmetry axes of the material, the wave energy in the plate will skew. As the non-specular reflection field is composed of the energy which is leaked by the wave modes in the plate, this field will experience the same skewing [8]. For obvious reasons, the 2D model under consideration cannot capture this effect, and we restrict ourselves in Figure 4a to only showing the solution for = 0.…”

Section: Resultsmentioning

confidence: 99%

“…The positioning of the transducers is mechanically controlled, leading to relative long measurement times (~15 min) and a bulky, non-portable scanning system. Additionally, the finite aperture transducers produce bounded beams such that no pure Lamb modes [8] are induced. Finally, non-specular phenomena are not recorded although they contain supplementary information on the response of the insonified plate [9].…”

Section: Introductionmentioning

confidence: 99%

Towards a Phased Array Based Ultrasonic Polar Scan: Simulation Study and Comparison with Plane Wave Results

Daemen

Martens

Kersemans

et al. 2018

The 18th International Conference on Experimental Mechanics

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Abstract:The ever-increasing use of composite materials in the industry has resulted in the need for new, intricate approaches to not only properly characterize their anisotropic mechanical properties (i.e., the visco-elastic tensor), but also to detect various types of internal flaws. Both goals can be achieved by the Ultrasonic Polar Scan (UPS). During an UPS experiment, a material spot is insonified at many oblique incidence angles Ψ(θ,φ), with θ the vertical incident angle and φ the inplane polar angle, after which the reflected or transmitted ultrasound signal is recorded. The resulting dataset provides an integral view of the angle-dependent reflection (R) and transmission (T) scatter coefficients, and can be employed to infer the material properties. Although the current UPS scanner provides highly accurate experimental data, it is impractical for in-situ measurements. In order to create a more compact and practical measuring device, we propose the use of a hemispherical phased array, consisting of small piezoelectric elements, to generate a broadband, quasi plane wave signal. It will be shown, based on simulations, that a circular phased array concept allows for the determination of the reflection coefficients in θ − f space, from which the dispersion curves can be immediately inferred. Comparison of these results with the plane wave theoretical results show an excellent agreement.

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“…The dispersion relation of Lamb waves in a 5.72-mm glass plate, calculated from well known theory [6], is given in Fig. 1.…”

Section: Zero Group Velocitymentioning

confidence: 99%

High contrast air-coupled acoustic imaging with zero group velocity lamb modes

Holland

Chimenti

2004

Ultrasonics

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The well known zero in the group velocity of the first-order symmetric (S 1 ) plate wave mode has been exploited in air-coupled ultrasonic imaging to obtain significantly higher sensitivity than can be achieved in conventional air-coupled scanning. At the zero group velocity point at the frequency minimum of the S 1 mode, a broad range of wavenumbers couple into the first-order symmetric mode at nearly a constant frequency, greatly enhancing transmission at that frequency. Coupled energy remains localized near the coupling point because the group velocity is zero. We excite the mode with a broadband, focussing, aircoupled transducer at the frequency of the zero group velocity point in the S 1 mode. By exploiting the efficient coupling at the zero group velocity frequency, we have easily imaged a single layer of Scotch tape attached to a 6.4-mm thick Plexiglas plate and 3.2-mm Teflon inserts in a composite laminate. AbstractThe well known zero in the group velocity of the first-order symmetric (S 1 ) plate wave mode has been exploited in air-coupled ultrasonic imaging to obtain significantly higher sensitivity than can be achieved in conventional air-coupled scanning. At the zero group velocity point at the frequency minimum of the S 1 mode, a broad range of wavenumbers couple into the first-order symmetric mode at nearly a constant frequency, greatly enhancing transmission at that frequency. Coupled energy remains localized near the coupling point because the group velocity is zero. We excite the mode with a broadband, focussing, air-coupled transducer at the frequency of the zero group velocity point in the S 1 mode. By exploiting the efficient coupling at the zero group velocity frequency, we have easily imaged a single layer of Scotch tape attached to a 6.4-mm thick Plexiglas plate and 3.2-mm Teflon inserts in a composite laminate.

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Wave Propagation in Layered Anisotropic Media with Applications to Composites

Cited by 114 publications

References 2 publications

Damage detection in composite materials using Lamb wave methods

Damage detection in composite materials using Lamb wave methods

Towards a Phased Array Based Ultrasonic Polar Scan: Simulation Study and Comparison with Plane Wave Results

High contrast air-coupled acoustic imaging with zero group velocity lamb modes

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