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Noncontact, high-resolution ultrasonic imaging of wood samples using coded chirp waveforms
Tat Hean Gan1, David A Hutchins, Roger J Green
1School of Engineering, University of Warwick, Coventry CV4 7AL, UK. t.h.gan@warwick.ac.uk
Summary
This study introduces a noncontact ultrasonic inspection method for wood properties. Advanced signal processing significantly improves signal quality, enabling detection of wood density and microcracks.
Area of Science:
- Materials Science
- Acoustics
- Non-Destructive Testing
Background:
- Traditional wood property analysis often requires destructive methods.
- Non-destructive evaluation (NDE) techniques are crucial for material assessment.
- Ultrasonic testing offers potential for NDE but faces challenges with signal attenuation and noise in air.
Purpose of the Study:
- To develop and validate a noncontact ultrasonic inspection technique for wood.
- To enhance signal quality for improved data acquisition from wood samples.
- To demonstrate the capability of extracting key wood properties using this method.
Main Methods:
- Utilized two broad bandwidth capacitive transducers for noncontact ultrasonic wave transmission.
- Employed a coded chirp signal for enhanced waveform sensitivity across wood samples.
- Applied signal recovery techniques: pulse compression and swept frequency multiplication (SFM) to improve signal-to-noise ratio (SNR).
Main Results:
- Demonstrated significant SNR improvement using pulse compression and SFM.
- Validated simulation results with experimental data.
- Successfully extracted wood properties, including ring density and microcrack detection.
Conclusions:
- Noncontact ultrasonic inspection is feasible for studying wood properties in air.
- Advanced signal processing techniques effectively overcome signal degradation.
- The developed method provides a viable NDE tool for wood quality assessment.