Envelope correction for shear-longitudinal collinear wave mixing to extract absolute nonlinear acoustic parameters

Area of Science:

• Nonlinear acoustics
• Materials science
• Wave propagation

Background:

• Nonlinear resonant signal (NRS) analysis is crucial for material property characterization.
• Excitation waveform envelopes can influence the accuracy of measured material nonlinearity.
• Extracting absolute material nonlinearity requires precise understanding of wave mixing phenomena.

Purpose of the Study:

• To investigate the impact of excitation envelope on nonlinear resonant signal (NRS).
• To develop a method for accurate extraction of absolute material nonlinearity.
• To validate theoretical waveform corrections experimentally for collinear shear-longitudinal wave mixing.

Main Methods:

• Finite difference time domain (FDTD) modeling to simulate waveform effects on NRS.
• Theoretical derivation of waveform correction factors.
• Experimental validation using different input waveforms and amplitudes.
• Extraction of the Murnaghan constant (m) using corrected NRS data.

Main Results:

• A significant change in measured nonlinearity was observed when altering input waveforms (rectangular vs. Hanning windowed tone burst).
• Theoretical corrections were derived and experimentally validated for mapping NRS to a reference amplitude.
• Hanning tone burst inputs demonstrated lower variance in extracted material properties compared to rectangular inputs.
• The Murnaghan constant (m) was successfully extracted using the validated correction method.

Conclusions:

• Excitation envelope significantly affects nonlinear resonant signal measurements.
• Hanning windowed tone bursts provide more reliable and precise measurements of absolute material nonlinearity.
• The developed correction method enables accurate determination of material properties like the Murnaghan constant (m) via collinear wave mixing.