Nonlinear coda wave interferometry for the global evaluation of damage levels in complex solids

Area of Science:

• Nonlinear acoustics
• Materials science
• Solid mechanics

Background:

• Assessing material damage is crucial for structural integrity.
• Conventional ultrasonic methods face limitations in complex media.
• Nonlinear elastic signatures of cracks offer potential for damage detection.

Purpose of the Study:

• To develop and validate a nonlinear acoustic method for damage assessment in complex media.
• To differentiate between linear scattering and nonlinear scattering from cracks.
• To apply coda wave interferometry (CWI) for damage level quantification.

Main Methods:

• Utilized nonlinear acoustics to analyze wave signatures from internal solid contacts and cracks.
• Employed coda wave interferometry (CWI) on reverberated and scattered waves in damaged glass plates.
• Recorded ultrasonic coda signals with and without a low-frequency pump wave for nonlinear wave-mixing analysis.

Main Results:

• CWI parameters quantifying nonlinear wave-mixing effects were found to be dependent on the sample's damage level.
• The method successfully distinguished nonlinear scattering from cracks from linear scattering by heterogeneities.
• Parametric study investigated the influence of sensor positions and temperature on the method's output.

Conclusions:

• The developed nonlinear acoustic method shows promise for non-destructive testing and evaluation of complex materials.
• This technique overcomes limitations of conventional ultrasonic methods in multiple scattering samples.
• The approach provides a sensitive measure of material damage through nonlinear wave interactions.