Double open resonator for localized non-contact acoustic testing

Document type: Conference Papers
Peer reviewed: Yes
Full text:
Author(s): Claes Hedberg, Kristian Haller
Title: Double open resonator for localized non-contact acoustic testing
Translated title: Dubbel öppen resonator för lokaliserad oberörande akustisk provning
Conference name: International Congress on Acoustics, April 4-9, 2004.
Year: 2004
Pagination: CD-rom
ISBN: 4-9901915-6-0
Publisher: International Commission of Acoustics
City: Kyoto
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Mechanical Engineering (Sektionen för teknik – avd. för maskinteknik)
School of Engineering S- 371 79 Karlskrona
+46 455 38 50 00
Authors e-mail:
Language: English
Abstract: There exist two concepts of open resonators that can be combined into a device for acoustic non-destructive testing. The device is non-contact and based on the fact that an airgap between a transducer surface and the test object can be set into resonance. This occurs for the conditions that makes this an open resonator (open because the air volume is not closed), and the wave field is amplified so that a larger amplitude is reached at the object surface. Let us assume that the object is a plate. When the acoustic wave enters the plate, one can let the frequency be the resonant frequency for one of the modes for the plate thickness. A limited part of the plate may be seen as a resonator, open to the sides. When the conditions for an open resonator is fulfilled for the plate thickness, the wave field will be greatly amplified within a region close to the insonified plate surface, and thus the linear or nonlinear response from this excitation is local. The device may then be used to scan the plate for material parameter changes.
Subject: Mechanical Engineering\Structural Dynamics
Keywords: nonlinear acoustics, localized NDT, nonlinear NDT