An Adaptive Array Excitation Scheme for the Unidirectional Enhancement of Guided Waves.
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Author(s)
Type
Journal Article
Abstract
Control over the direction of wave propagation allows an engineer to spatially locate defects. When imaging with longitudinal waves, time delays can be applied to each element of a phased array transducer to steer a beam. Because of the highly dispersive nature of guided waves (GWs), this beamsteering approach is suboptimal. More appropriate time delays can be chosen to direct a GW if the dispersion relation of the material is known. Existing techniques, however, need a priori knowledge of material thickness and acoustic velocity, which change as a function of temperature and strain. The scheme presented here does not require prior knowledge of the dispersion relation or properties of the specimen to direct a GW. Initially, a GW is generated using a single element of an array transducer. The acquired waveforms from the remaining elements are then processed and retransmitted, constructively interfering with the wave as it travels across the spatial influence of the transducer. The scheme intrinsically compensates for the dispersion of the waves, and thus can adapt to changes in material thickness and acoustic velocity. The proposed technique is demonstrated in simulation and experimentally. Dispersion curves from either side of the array are acquired to demonstrate the scheme's ability to direct a GW in an aluminum plate. The results show that unidirectional enhancement is possible without a priori knowledge of the specimen using an arbitrary pitch array transducer. The experimental results show a 34-dB enhancement in one direction compared with the other.
Date Issued
2016-11-11
Online Publication Date
2016-11-11
2018-01-15T14:18:18Z
Date Acceptance
2016-11-07
ISSN
0885-3010
Publisher
Institute of Electrical and Electronics Engineers
Start Page
441
End Page
451
Journal / Book Title
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Volume
64
Issue
2
Copyright Statement
This work is licensed under a Creative Commons Attribution 3.0 License. For more information, see http://creativecommons.org/licenses/by/3.0/
Source Database
web-of-science
Subjects
Science & Technology
Technology
Acoustics
Engineering, Electrical & Electronic
Engineering
Bandwidth
chirp
control systems
delay effects
dispersion
energy resolution
imaging
inspection
material properties
phased arrays
signal resolution
signal to noise ratio
steel
transducers
transforms
LAMB WAVES
NONDESTRUCTIVE EVALUATION
DEFECT DETECTION
IN-VITRO
ULTRASOUND APPLICATIONS
SOURCE LOCALIZATION
TRANSDUCER ARRAY
CHIRP EXCITATION
GENERATION
INSPECTION
02 Physical Sciences
09 Engineering
Publication Status
Published