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Diffuse energy transport and coda-wave interferometry for resonant transmission between reverberant structures
Richard L Weaver1, SangMin Lee2
1Department of Physics, University of Illinois, Urbana, Illinois 61801, USA.
The Journal of the Acoustical Society of America
|September 2, 2021
Summary
This study models ultrasonic fields transmitted between elastic bodies. Theories accurately predict signal behavior and time delays caused by frequency shifts, aiding nonlinear elasticity measurements.
Area of Science:
- Acoustics and Materials Science
- Solid Mechanics and Wave Propagation
Background:
- Understanding wave propagation through coupled elastic bodies is crucial for material characterization.
- Dynamic elastic nonlinearity affects wave transmission, necessitating accurate modeling techniques.
Purpose of the Study:
- To develop and validate approximate analytic and numerical theories for modeling diffuse ultrasonic fields.
- To investigate the sensitivity of transmitted ultrasonic fields to resonant coupling frequency perturbations.
- To analyze the manifestation of frequency perturbations as time delays in the receiving elastic body.
Main Methods:
- Development of approximate analytic and numerical theories for ultrasonic field modeling.
- Comparison of theoretical models with laboratory measurements of transmitted ultrasonic signals.
- Analysis of signal time dependence, spectra, and time delays.
Main Results:
- The developed theories accurately predict the time dependence of the mean square transmitted signal and signal spectra.
- Theories successfully predict the erratic nature and mean values of observed time delays.
- Analytic dependence of time shifts on fractional frequency perturbation (df/f) was derived.
Conclusions:
- Approximate theories provide a reliable framework for modeling ultrasonic wave transmission through resonant couplings.
- The study demonstrates a method for measuring slow dynamic elastic nonlinearity using ultrasonic time delays.
- Frequency perturbations in resonant couplings are directly linked to measurable time delays in transmitted ultrasonic fields.
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