Mode propagation of ultrasound in hollow waveguides

Nicholson, Nannette; McDicken, W.N.

doi:10.1016/0041-624x(91)90094-o

Cited by 13 publications

(5 citation statements)

References 4 publications

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“…Elastic waves guided by the wall of a hollow cylinder are similar to Lamb waves, even for high values of the ratio b / a of external to internal radius. From the dispersion curves ͑k͒ calculated for hollow cylinders of Poisson's ratio 0.3, 19 it can be shown that S 1 and the A 2 modes exhibit a horizontal slope for b / a up to 2. These curves also show that the parameters ␤ 1 and ␤ 2 vary with thickness.…”

Section: Resultsmentioning

confidence: 99%

Local and noncontact measurements of bulk acoustic wave velocities in thin isotropic plates and shells using zero group velocity Lamb modes

Clorennec

Prada

Royer

2007

Journal of Applied Physics

110

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An original method for material characterization with acoustic waves is presented. The measurement of the longitudinal and shear wave velocities in thin isotropic plates or shells is performed locally on the same face without any mechanical contact. We exploit the resonance that occurs at the minimum frequency thickness product of the first order symmetric (S1) and of the second order antisymmetric (A2) Lamb modes. At these frequencies the group velocity vanishes, whereas the phase velocity remains finite. Then, the energy, which cannot propagate in the structure, is localized in a zone of diameter half the wavelength. The vibrations are excited in the thermoelastic regime by a laser pulse and detected at the same point by an optical interferometer. For these two Lamb modes we have computed the variations of the frequency thickness product versus Poisson’s ratio. The resonance frequency ratio, which is independent of the plate or shell thickness, provides an absolute and local measurement of Poisson’s ratio. Provided that the plate thickness is known, each resonance frequency allows us to determine in a single shot the bulk acoustic wave velocities VL and VT. Since it is based on frequency measurements, the method, tested on a large number of materials, is very accurate.

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Section: Resultsmentioning

confidence: 99%

Local and noncontact measurements of bulk acoustic wave velocities in thin isotropic plates and shells using zero group velocity Lamb modes

Clorennec

Prada

Royer

2007

Journal of Applied Physics

110

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“…The number of modes present at a given frequency in a solid waveguide (geometrical structure capable of propagating energy in a preferred direction) is dependent on the radius of the waveguide. In a hollow cylinder, the critical dimensions are the wall thickness and the ratio of the external to internal wall diameter [33]. Practically, these wave modes are operated in the frequency range of 20-100kHz and called LRUT.…”

Section: Mode Types and Nomenclaturementioning

confidence: 99%

Challenges in Monitoring Metallic Pipeline Corrosion Using Ultrasonic Waves – A Review Article

Gunarathna¹,

Sivahar

2021

Engineer

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Corrosion is a widespread problem in metallic pipelines. Copious use of pipelines across many industries urges the application of inspection technologies for early detection of corrosion in order to prevent its costly and fatal outcomes. As of today, there is a range of ultrasonic techniques that cater to finding and sizing of the extent of corrosion. For piping inspection, guided wave (GW) modes are of interest for detecting corrosion defects as they offer rapid scanning over extended distances. Over the past three decades, the use of GWs have progressed tremendously and are commonplace today. More complex testing units have been fabricated because of recent advances in the fields of smart materials, electronics, and communication technologies. However, GW signals contain multiple modes and only a handful of them are used in inspection. This paper aims to provide an overview of current GW approaches focused on the detection, localization, and evaluation of corrosion defects in pipelines. The study presents a literature review of the main issues encountered in pipeline systems when using GWs and recent attempts to overcome the barriers.

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“…This phenomenon occurs at frequencies where two or more modes have equal phase velocities and share energy. This gives rise to a greater loss of accuracy in determining true modes of propagation [23]. In order to recognize the likelihood of the propagated modes used in this application, various considerations were taken.…”

Section: Possible Axisymmetric Mode Receptionmentioning

confidence: 99%

Flood member detection for real-time structural health monitoring of sub-sea structures of offshore steel oilrigs

Mijarez

Gaydecki

Burdekin³

2007

Smart Mater. Struct.

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A structural flood detection system for real-time health monitoring in the hollow sub-sea members of new offshore steel oilrigs is presented. Field-proven flood member detection techniques, integrated within the concept of health monitoring, offer an alternative to underwater nondestructive testing methods based on ultrasound and x-rays, which have been used to detect the presence of seawater in these applications, often with diverse or remote operating vehicles. The system employs a single piezoelectric transducer which can be permanently attached to the inner wall of every sub-sea structure and which is powered by a normally inert seawater battery. Upon activation, the sensor transmits ultrasonic chirp or tone encoded pulses, in the range of 21–42 kHz, to a monitoring receiver system at deck level for decoding and identifying flooded members. Experiments have been carried out using a jointed steel pipe structure, 7 m in length, 0.5 m in diameter and 16 mm in thickness. This structure was flooded and completely immersed in seawater. Two approaches to the system were considered during the investigation, depending on the communication channel exploited; the former utilized guided waves, on the basis of exploiting the steel structure as a wave-guide; the latter employed underwater ultrasound, based on using the seawater as a propagation medium. Although severe losses were encountered in both approaches, the system effectively identified the signals above the background noise. This work forms the foundation for the future development of a system that can be used with large, commercial offshore platforms.

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Mode propagation of ultrasound in hollow waveguides

Cited by 13 publications

References 4 publications

Local and noncontact measurements of bulk acoustic wave velocities in thin isotropic plates and shells using zero group velocity Lamb modes

Local and noncontact measurements of bulk acoustic wave velocities in thin isotropic plates and shells using zero group velocity Lamb modes

Challenges in Monitoring Metallic Pipeline Corrosion Using Ultrasonic Waves – A Review Article

Flood member detection for real-time structural health monitoring of sub-sea structures of offshore steel oilrigs

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