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Detecting the thickness mode frequency in a concrete plate using backward wave propagation
Henrik Bjurström1, Nils Ryden1
1Division of Soil- and Rock Mechanics, KTH Royal Institute of Technology, Brinellvägen 23, 114 28 Stockholm, Sweden.
The Journal of the Acoustical Society of America
|March 4, 2016
Summary
This study presents a new non-destructive method for estimating concrete plate thickness using seismic wave analysis. The technique detects specific wave behaviors to determine thickness, offering an alternative to the Impact Echo method.
Area of Science:
- Civil Engineering
- Materials Science
- Non-Destructive Testing
Background:
- Material stiffness and plate thickness are critical for pavement quality control.
- The Impact Echo (IE) method estimates thickness via resonance frequency but struggles with non-contact receivers due to low signal-to-noise ratio.
Purpose of the Study:
- To introduce an alternative non-destructive technique for estimating concrete plate thickness.
- To overcome limitations of the Impact Echo method, particularly with non-contact receivers.
Main Methods:
- Analyzing complex Lamb wave dispersion curves slightly above the thickness resonance frequency.
- Detecting waves with negative phase velocity using accelerometers and air-coupled microphones.
Main Results:
- Identified two counter-directed waves occurring at the same frequency but with opposite phase velocities.
- Successfully detected the negative phase velocity wave using both contact and non-contact receivers.
Conclusions:
- The alternative technique enables non-destructive thickness determination of concrete plates.
- This method shows potential for non-contact scanning measurements using air-coupled microphones.
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