uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Direction of Arrival Estimation of Lamb Waves Using Circular Arrays
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group. (NDT)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group. (NDT)
2011 (English)In: Structural Health Monitoring, ISSN 1475-9217, E-ISSN 1741-3168, Vol. 10, no 5, 467-480 p.Article in journal (Refereed) Published
Abstract [en]

 Uniform circular arrays (UCAs) with 360 degrees azimuthal coverage are very useful for structural health monitoring (SHM) of large planar structures. Difficulties encountered when working with Lamb waves include their dispersive and multi-modal nature. In this paper three different methods for estimating the direction-of-arrival (DOA) of incoming Lamb waves are compared and verified using simulated and experimental data. The previously proposed phase-mode excitation based beamformer is compared with two high-resolution spectral estimation techniques, the Capon method and the multiple signal classification method (MUSIC). Design consideration and guidelines for UCAs are presented. To experimentally evaluate the performance of the considered DOA methods a prototype array consisting of 16 separate pinducers arranged in a ring was constructed. The array was provided with an analog multiplexer that enabled recording signals received by the individual elements using a digital oscilloscope. The array was used for the reception of ultrasonic pulses sent by broadband piezoelectric transmitters and propagating in an aluminum plate. A selection of simulation and experimental results is presented showing the superior performance of the Capon beamformer.

Place, publisher, year, edition, pages
2011. Vol. 10, no 5, 467-480 p.
Keyword [en]
array signal processing, adaptive beamforming, guided waves, dispersive waves, multi-modal waves
National Category
Engineering and Technology
Research subject
Electrical Engineering with specialization in Signal Processing
URN: urn:nbn:se:uu:diva-122107DOI: 10.1177/1475921710379512ISI: 000294287000002OAI: oai:DiVA.org:uu-122107DiVA: diva2:309347
Available from: 2010-04-07 Created: 2010-04-06 Last updated: 2016-04-20Bibliographically approved
In thesis
1. Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves
Open this publication in new window or tab >>Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Non-destructive testing (NDT) techniques are critical to ensure integrity and safety of engineered structures. Structural health monitoring (SHM) is considered as the next step in the field enabling continuous monitoring of structures.

The first part of the thesis concerns NDT and SHM using guided waves in plates, or Lamb waves, to perform imaging of plate structures. The imaging is performed using a fixed active array setup covering a larger area of a plate. Current methods are based on conventional beamforming techniques that do not efficiently exploit the available data from the small arrays used for the purpose. In this thesis an adaptive signal processing approach based on the minimum variance distortionless response (MVDR) method is proposed to mitigate issues related to guided waves, such as dispersion and the presence of multiple propagating modes. Other benefits of the method include a significant increase in resolution. Simulation and experimental results show that the method outperforms current standard processing techniques.

The second part of the thesis addresses transducer design issues for resonant ultrasound inspections. Resonant ultrasound methods utilize the shape and frequency of the object's natural modes of vibration to detect anomalies. The method considered in the thesis uses transducers that are acoustically coupled to the inspected structures. Changes in the transducer's electrical impedance are used to detect defects. The sensitivity that can be expected from such a setup is shown to highly depend on the transducer resonance frequency, as well as the working frequency of the instrument. Through simulations and a theoretical argumentation, optimal conditions to achieve high sensitivity are given.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 83 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 732
imaging, array processing, guided waves, Lamb waves, dispersive waves, multi-modal waves, spatial filtering, mode suppression, resonant ultrasound, transducer design, direction of arrival estimation, adaptive beamforming
National Category
Signal Processing Control Engineering
urn:nbn:se:uu:diva-122189 (URN)978-91-554-7785-1 (ISBN)
Public defence
2010-05-21, Siegbahnsalen, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2010-04-28 Created: 2010-04-07 Last updated: 2010-04-28Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Engholm, MarcusStepinski, Tadeusz
By organisation
Signals and Systems Group
In the same journal
Structural Health Monitoring
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 201 hits
ReferencesLink to record
Permanent link

Direct link